Experiences of caregivers of boys with Duchenne Muscular Dystrophy: "When I look at him, my world falls apart" / Experiencias de cuidadoras de niños con Distrofia Muscular de Duchenne: "Cuando lo volteo a mirar, se me une el cielo con la tierra"

Resumen La Distrofia Muscular de Duchenne (DMD) es una enfermedad neuromuscular, clasificada como una enfermedad huérfana o rara, transmitida por la madre, y que conlleva al deterioro físico progresivo y fatal de quienes la desarrollan, que en su mayoría son hombres. Aun con los tratamientos farmacológicos disponibles, el pronóstico de vida de los pacientes sigue siendo desalentador. Los niños van perdiendo progresivamente la movilidad y funcionalidad hasta que fallecen. En consecuencia, el progreso de esta enfermedad requiere de cuidados frecuentes o permanentes que implican altos niveles de exigencia para las cuidadoras de niños y de jóvenes que han desarrollado la DMD. El apoyo proveniente del sistema de salud es escaso para ambos, lo que se traduce en una intensa sobrecarga para las madres y mujeres de la familia que son quienes, habitualmente, cuidan a la persona diagnosticada con DMD durante su vida. Este estudio cualitativo de tipo fenomenológico tuvo como objetivos analizar el significado de la experiencia de ser cuidadora de niños y jóvenes que viven con DMD en Colombia, develando el sentido que tiene para las mujeres familiares asumir el rol de cuidadora. Se entrevistaron siete mujeres entre los 25 y los 64 años encargadas de cuidar, por lo menos, a un niño o joven con diagnóstico de DMD, previo consentimiento informado. Adicionalmente, los cuidadores desarrollaron un ejercicio de asociaciones libres. Para el análisis de datos se realizó un análisis temático de las narrativas, encontrando tres temas fundamentales alrededor de los cuales se le da sentido a esta experiencia: (1) descubrir la enfermedad, (2) vivir en función del paciente y (3) reconstruir el sentido de vida. Así, en un momento inicial las cuidadoras se enfrentan al diagnóstico de la enfermedad brindado por los médicos, quienes les explican su curso y su naturaleza. La cuidadora inicia un proceso de duelo, en el que la tristeza, la negación y la resignación tienen lugar, y emociones como la frustración y la impotencia se presentan en su máxima expresión. La manera en la que es comunicado el diagnóstico es evaluada por las cuidadoras como poco sensible. De hecho, ninguna de las participantes en el estudio recibió apoyo psicológico durante el proceso. En segundo lugar, ser la figura de cuidado implicó cambios a nivel personal, familiar y social, para lograr responder a las necesidades de los niños con DMD. En este sentido, algunas debieron renunciar a sus empleos, alejarse de amistades e incluso algunas manifestaron que se han separado de su pareja o han vivido experiencias de deterioro en las relaciones con su pareja y familia extensa. Además, junto con sus hijos han vivenciado experiencias de discriminación, vulneración de derechos y escaso apoyo social, experiencias que son factores de riesgo para la salud mental. Finalmente, la enfermedad termina por constituirse en el elemento vinculante entre ellas y sus niños. Los hallazgos de la presente investigación permiten identificar que, en el proceso de enfermedad, se produce una reconstrucción del sentido de vida. Así, las estrategias de afrontamiento se dirigen a lograr una transformación espiritual. La presencia de la enfermedad es interpretada como una manera de ser probadas y desarrollar sus cualidades como mujer y como madre. Entonces, el cuidado y la relación madre-hijo, son componentes motivacionales que transforman y dan sentido a la vida. En conclusión, los resultados muestran que el significado de la DMD está fuertemente vinculado a un proceso de intenso sufrimiento y estrés psicológico, con alta carga negativa. En particular, durante los primeros años después del diagnóstico, que debe ser asimilado y elaborado para aprender a convivir con la DMD y la certeza de la muerte prematura de un hijo.

Abstract Duchenne muscular dystrophy (DMD) is a neuromuscular disease that leads to progressive and fatal physical deterioration. The progression of this disease requires frequent or permanent care that implies high levels of demand for the caregivers of children who have developed DMD. Certainly, this disease affects diagnosed children and their caregivers as well. The support from the health system is scarce for both, which translates into an intense burden for the mothers and women of the family who care the person diagnosed with DMD during their lifetime. This qualitative study with phenomenological approach aimed to analyze the meaning of the experience of being a caregiver for boys and young men living with DMD in Colombia. After obtaining their informed consent, caregivers were interviewed and a thematic analysis of their narratives was performed to determine three key topics that endow their experiences with meaning: (1) finding out about the disease, (2) living according to the needs of boys and young men, and (3) providing a new meaning to life. The results show that the meaning of DMD is strongly associated with intense suffering and psychological stress, with a high negative burden, especially during the initial years after diagnosis. The study suggests that it is important to assimilate and process these experiences and findings to learn how to live with DMD and identify the certainty of a child's premature death.

The experience of Colombian boys and young men living with Duchenne muscular dystrophy / A experiência dos meninos e jovens colombianos que vivem com distrofia muscular de Duchenne / L'expérience des garçons et des jeunes hommes colombiens vivant avec dystrophie musculaire de Duchenne / La experiencia de niños y jóvenes colombianos que viven con distrofia muscular de Duchenne

Abstract Duchenne muscular dystrophy (DMD) is a chronic disease that primarily affects males and is characterized by progressive physical impairment and, eventually, death. This qualitative study aimed to explore and understand the experience of diagnosis and disease in young people with DMD living in Bogotá, Colombia. After securing approval from the Research Ethics Committee (CEI-ABN026-000311), nine individuals took part of a semi-structured interview, and their narratives were analyzed using thematic analysis. The main topics developed throughout the narratives were: negative representation of the disease; fear; difficulty expressing emotions; the patient-doctor relationship; the wheelchair; the caregivers and coping strategies. We conclude that young people affected by DMD face several challenging experiences that underscore the need for better, more respectful, and compassionate interactions with healthcare providers. Also, their experiences are indicative of a socio-cultural context that needs to become more responsive and compassionate towards young people and disability.

Resumo A distrofia muscular de Duchenne (DMD) é uma doença crônica que afeta principalmente os homens, caracterizada pelo deterioro físico progressivo e por conduzir à morte. Este estudo qualitativo teve como objetivo a exploração e a compreensão da experiência do diagnóstico e da doença em jovens com DMD residentes em Bogotá, Colômbia. Após a aprovação do Comitê de Ética em Pesquisa (CEI-ABN026-000311), nove participantes participaram numa entrevista semiestruturada e as suas narrativas foram analisadas através da análise temática. Os principais temas abordados foram: a representação negativa da doença; o medo; a dificuldade em expressar emoções; a relação paciente-médico; a cadeira de rodas; os cuidadores e as estratégias de resiliência. Concluímos que os jovens afetados pela DMD enfrentam experiências desafiantes que evidenciam a necessidade de interações melhores, mais respeitosas e compassivas com os profissionais de saúde. Ao mesmo tempo, as suas experiências são indicativas de um contexto sociocultural que precisa de se tornar mais recetivo e compassivo para com os jovens e as deficiências.

Résumé La Dystrophie Musculaire de Duchenne (DMD) est une maladie chronique qui touche principalement les hommes et se caractérise par détérioration physique progressive et, éventuellement, la mort. Cette rechérche qualitative a explorer l'expérience du diagnostic et de la maladie chez les jeunes atteints de DMD à Bogotá, Colombie. Cette rechérche a été évaluée et approuvée par un comité d'éthique de la recherche (CEI-ABN026-000311). Neuf jeunes ont participé à un entretien semi-structuré et leurs récits ont été analysés à l'aide d'une analyse thématique. Les principaux thèmes développés dans les récits étaient: la représentation négative de la maladie; peur; difficulté à exprimer ses émotions; la relation médecin-patient; le fauteuil roulant; soignants et stratégies d'adaptation. Nous concluons que les jeunes touchés par la DMD vivent de multiples expériences difficiles qui mettent en évidence la nécessité d'interactions plus respectueuses et plus compatissantes avec les prestataires de services de santé. En même temps, leurs expériences montrent un contexte socioculturel qui doit être plus sensible et compatissant envers les enfants et les jeunes handicapés.

Resumen La distrofia muscular de Duchenne (DMD) es una enfermedad crónica que afecta principalmente a hombres y se caracteriza por deterioro físico progresivo y, eventualmente, la muerte. Este estudio cualitativo buscó explorar y comprender la experiencia del diagnóstico y la enfermedad en jóvenes con DMD en la ciudad de Bogotá, Colombia. Tras recibir autorización del Comité de Ética en Investigación (CEI-ABN026-000311), nueve participantes colaboraron con una entrevista semiestructurada y sus narrativas fueron analizadas usando análisis temático. Los principales temas desarrollados en las narrativas fueron: representación negativa de la enfermedad; miedo; dificultad expresando emociones; la relación médico-paciente; la silla de ruedas; los cuidadores y las estrategias de afrontamiento. Concluimos que los jóvenes afectados por la DMD enfrentan múltiples experiencias retadoras que hacen evidente la necesidad de interacciones más respetuosas y compasivas con los proveedores de servicios de salud. Al mismo tiempo, sus experiencias muestran un contexto sociocultural que necesita ser más sensible y compasivo con los niños y jóvenes en situación de discapacidad.

Mutant GNLY is linked to Stevens-Johnson syndrome and toxic epidermal necrolysis.

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are rare severe cutaneous adverse reactions to drugs. Granulysin (GNLY) plays a key role in keratinocyte apoptosis during SJS/TEN pathophysiology. To determine if GNLY-encoding mutations might be related to the protein's functional disturbances, contributing to SJS/TEN pathogenesis, we performed direct sequencing of GNLY's coding region in a group of 19 Colombian SJS/TEN patients. A GNLY genetic screening was implemented in a group of 249 healthy individuals. We identified the c.11G > A heterozygous sequence variant in a TEN case, which creates a premature termination codon (PTC) (p.Trp4Ter). We show that a mutant protein is synthesised, possibly due to a PTC-readthrough mechanism. Functional assays demonstrated that the mutant protein was abnormally located in the nuclear compartment, potentially leading to a toxic effect. Our results argue in favour of GNLY non-synonymous sequence variants contributing to SJS/TEN pathophysiology, thereby constituting a promising, clinically useful molecular biomarker.

Cost-Effectiveness Analysis of Diagnosis of Duchenne/Becker Muscular Dystrophy in Colombia.

OBJECTIVES: To determine the cost-effectiveness ratio of different courses of action for the diagnosis of Duchenne or Becker muscular dystrophy in Colombia. METHODS: The cost-effectiveness analysis was performed from the Colombian health system perspective. Decision trees were constructed, and different courses of action were compared considering the following tests: immunohistochemistry (IHC), Western blot (WB), multiplex polymerase chain reaction, multiplex ligation-dependent probe amplification (MLPA), and the complete sequencing of the dystrophin gene. The time horizon matched the duration of sample extraction and analysis. Transition probabilities were obtained from a systematic review. Costs were constructed with a type-case methodology using the consensus of experts and the valuation of resources from consulting laboratories and the 2001 Social Security Institute cost manual. Deterministic sensitivity and scenario analyses were performed with one or more unavailable alternatives. Costs were converted from Colombian pesos to US dollars using the 2014 exchange rate. RESULTS: In the base case, WB was the dominant strategy, with a cost of US $419.07 and a sensitivity of 100%. This approach remains the dominant strategy down to a 98.2% sensitivity and while costs do not exceed US $837.38. If WB was not available, IHC had the best cost-effectiveness ratio, followed by MLPA and sequencing. CONCLUSIONS: WB is a cost-effective alternative for the diagnosis of patients suspected of having Duchenne or Becker muscular dystrophy in the Colombian health system. The IHC test is rated as the second-best detection method. If these tests are not available, MLPA followed by sequencing would be the most cost-effective alternative.

A first description of the Colombian national registry for rare diseases.

OBJECTIVE: Orphan diseases must be considered a public health concern, underlying country-specific challenges for their accurate and opportune diagnosis, classification and management. Orphan disease registries have not yet been created in South America, a continent having a population of ~ 415 million inhabitants. In Colombia ~ 3 million of patients are affected by rare diseases. The aim of the present study was to establish the first Colombian national registry for rare diseases. The registry was created after the establishment of laws promoting the development of clinical guidelines for diagnosis, management, census and registry of patients suffering rare diseases. RESULTS: In total, 13,215 patients were recorded in the Colombian registry. The survey reported 653 rare diseases. The most common diseases were congenital factor VIII deficiency (hemophilia A) (8.5%), myasthenia gravis (6.4%), von Willebrand disease (5.9%), short stature due to growth hormone qualitative anomaly (4.2%), bronchopulmonary dysplasia (3.9%) and cystic fibrosis (3.2%). Although, a marked under-reporting of cases was observed, some pathologies displayed similar behavior to that reported by other initiatives and databases. The data currently available in the registry provides a baseline for improvement regarding local and regional surveys and the start for better understanding rare diseases in Colombia.

A homozygous donor splice-site mutation in the meiotic gene MSH4 causes primary ovarian insufficiency.

Premature ovarian insufficiency (POI) is a frequent pathology that affects women under 40 years of age, characterized by an early cessation of menses and high FSH levels. Despite recent progresses in molecular diagnosis, the etiology of POI remains idiopathic in most cases. Whole-exome sequencing of members of a Colombian family affected by POI allowed us to identify a novel homozygous donor splice-site mutation in the meiotic gene MSH4 (MutS Homolog 4). The variant followed a strict mendelian segregation within the family and was absent in a cohort of 135 women over 50 years of age without history of infertility, from the same geographical region as the affected family. Exon trapping experiments showed that the splice-site mutation induced skipping of exon 17. At the protein level, the mutation p.Ile743_Lys785del is predicted to lead to the ablation of the highly conserved Walker B motif of the ATP-binding domain, thus inactivating MSH4. Our study describes the first MSH4 mutation associated with POI and increases the number of meiotic/DNA repair genes formally implicated as being responsible for this condition.

Lack of association of polymorphisms in six candidate genes in colombian adhd patients.

BACKGROUND: Attention Deficit and Hyperactivity Disorder (ADHD) is a common childhood neuropsychiatric condition. The disorder has a multifactorial background, with heritability estimates of around 76%, suggesting an important role of genetic factors. Candidate genes include those related to dopaminergic (e.g. DRD4, DRD5, SLC6A3 and DBH)and serotoninergic (e.g.HTR1B and SLC6A4) pathways. PURPOSE: To explore the association of common polymorphisms in six genes (DRD4, DRD5, SLC6A3, DBH, HTR1B and SLC6A4) and the susceptibility to ADHD in a Colombian sample population. METHODS: trios and 152 healthy controls were recruited. Genotyping of the six polymorphisms was performed using described PCR-based protocols. A TDT analysis was used to test if there was preferential allelic transmission for any of the six polymorphisms. Additionally, a case-control analysis was performed to test for association of the serotoninergic (HTR1B and SLC6A4) polymorphisms with ADHD. RESULTS: Through the TDT analysis there was no preferential allelic transmission for any of the studied variants. Case-control analysis did not show association. CONCLUSION: This is the first study in Latin America to describe six polymorphisms in a group of patients with ADHD. There was no evidence of association for any of the studied polymorphic variants in this Colombian ADHD sample. Further research, with larger sample sizes and study of endophenotypes, is needed in this population to confirm and extend the results.

Identification of mutations in Colombian patients affected with Fabry disease.

Fabry Disease (FD) is an X-linked inborn error of glycosphingolipid catabolism, caused by a deficiency of the lisosomal α-galactosidase A (AGAL). The disorder leads to a vascular disease secondary to the involvement of kidney, heart and the central nervous system. The mutation analysis is a valuable tool for diagnosis and genetic counseling. Although more than 600 mutations have been identified, most mutations are private. Our objective was to describe the analysis of nine Colombian patients with Fabry disease by automated sequencing of the seven exons of the GLA gene. Two novel mutations were identified in two patients affected with the classical subtype of FD, in addition to other 6 mutations previously reported. The present study confirms the heterogeneity of mutations in Fabry disease and the importance of molecular analysis for genetic counseling, female heterozygotes detection as well as therapeutic decisions.

Next generation sequencing in women affected by nonsyndromic premature ovarian failure displays new potential causative genes and mutations.

OBJECTIVE: To identify new molecular actors involved in nonsyndromic premature ovarian failure (POF) etiology. DESIGN: This is a retrospective case-control cohort study. SETTING: University research group and IVF medical center. PATIENT(S): Twelve women affected by nonsyndromic POF. The control group included 176 women whose menopause had occurred after age 50 and had no antecedents regarding gynecological disease. A further 345 women from the same ethnic origin (general population group) were also recruited to assess allele frequency for potentially deleterious sequence variants. INTERVENTION(S): Next generation sequencing (NGS), Sanger sequencing, and bioinformatics analysis. MAIN OUTCOME MEASURE(S): The complete coding regions of 70 candidate genes were massively sequenced, via NGS, in POF patients. Bioinformatics and genetics were used to confirm NGS results and to identify potential sequence variants related to the disease pathogenesis. RESULT(S): We have identified mutations in two novel genes, ADAMTS19 and BMPR2, that are potentially related to POF origin. LHCGR mutations, which might have contributed to the phenotype, were also detected. CONCLUSION(S): We thus recommend NGS as a powerful tool for identifying new molecular actors in POF and for future diagnostic/prognostic purposes.

Evidence of association between SNAP25 gene and attention deficit hyperactivity disorder in a Latin American sample.

Attention deficit hyperactivity disorder (ADHD) is one of the most highly heritable behavioral disorders in childhood, with heritability estimates between 60 and 90 %. Family, twin and adoption studies have indicated a strong genetic component in the susceptibility to ADHD. The synaptosomal-associated protein of molecular weight 25 kDa (SNAP25) is a plasma membrane protein known to be involved in synaptic and neural plasticity. Animal model studies have shown that SNAP25 gene is responsible for hyperkinetic behavior in the coloboma mouse. In recent studies, several authors reported an association between SNAP25 and ADHD. In this study, we used a case-control approach to analyze the possible association of two polymorphisms of SNAP25 for possible association with ADHD in a sample of 73 cases and 152 controls in a Colombian children population. Polymorphisms are located in 3' untranslated region of SNAP25, positions T1065G and T1069C. We found a significant association with the GT haplotype (rs3746554|rs1051312) of SNAP25 (p = 0.001). Evidence of association was also found for the G/G genotype of rs3746554 (p = 0.002) and C/C genotype of rs1051312 (p = 0.009). This is the first study in a Latin American population. Similar to other studies, we found evidence of the association of SNAP25 and ADHD.

Sequence analysis of the ADRA2A coding region in children affected by attention deficit hyperactivity disorder.

Attention deficit hyperactivity disorder (ADHD) is a common neurobehavioral pathology characterized by distinct degrees of inattention, hyperactivity and impulsivity. Although ADHD etiology remains elusive, the ADRA2A candidate gene underlies a particular interest, since it participates in the prefrontal cortex regulation of executive function. Three SNPs located on 5' and 3'UTR regions of the gene have been extensively explored but none of them have been definitely validated as a predisposition or a causative sequence variation. In this study, in order to determine whether ADRA2A non-synonymous sequence variants, resulting in biochemical modifications of the protein, are a common cause of the disease we sequenced the complete ADRA2A coding region in a panel of ADHD children of Colombian origin. We identified the c.1138 C>A (p.Arg380Arg) silent substitution. We conclude that ADRA2A non-synonymous sequence variants do not cause ADHD in our sample population. We cannot formerly discard a potential role of this gene during ADHD pathogenesis since only the coding region was analysed. We hope that these results will encourage further researchers to sequence the promoter and coding regions of ADRA2A in large panels of ADHD patients from distinct ethnical origins.

A novel familial case of diffuse leukodystrophy related to NDUFV1 compound heterozygous mutations.

NDUFV1 mutations have been related to encephalopathic phenotypes due to mitochondrial energy metabolism disturbances. In this study, we report two siblings affected by a diffuse leukodystrophy, who carry the NDUFV1 c.1156C>T (p.Arg386Cys) missense mutation and a novel 42-bp deletion. Bioinformatic and molecular analysis indicated that this deletion lead to the synthesis of mRNA molecules carrying a premature stop codon, which might be degraded by the nonsense-mediated decay system. Our results add information on the molecular basis and the phenotypic features of mitochondrial disease caused by NDUFV1 mutations.

Identification and Functional Characterization of GAA Mutations in Colombian Patients Affected by Pompe Disease.

Pompe disease (PD) is a recessive metabolic disorder characterized by acid α-glucosidase (GAA) deficiency, which results in lysosomal accumulation of glycogen in all tissues, especially in skeletal muscles. PD clinical course is mainly determined by the nature of the GAA mutations. Although ~400 distinct GAA sequence variations have been described, the genotype-phenotype correlation is not always evident.In this study, we describe the first clinical and genetic analysis of Colombian PD patients performed in 11 affected individuals. GAA open reading frame sequencing revealed eight distinct mutations related to PD etiology including two novel missense mutations, c.1106 T > C (p.Leu369Pro) and c.2236 T > C (p.Trp746Arg). In vitro functional studies showed that the structural changes conferred by both mutations did not inhibit the synthesis of the 110 kD GAA precursor form but affected the processing and intracellular transport of GAA. In addition, analysis of previously described variants located at this position (p.Trp746Gly, p.Trp746Cys, p.Trp746Ser, p.Trp746X) revealed new insights in the molecular basis of PD. Notably, we found that p.Trp746Cys mutation, which was previously described as a polymorphism as well as a causal mutation, displayed a mild deleterious effect. Interestingly and by chance, our study argues in favor of a remarkable Afro-American and European ancestry of the Colombian population. Taken together, our report provides valuable information on the PD genotype-phenotype correlation, which is expected to facilitate and improve genetic counseling of affected individuals and their families.

Análisis de microdeleciones en 22q11 en pacientes colombianos con cardiopatía congénita no sindrómica / Analysis of microdeletions in 22q11 in Colombian patients with congenital heart disease

Los defectos cardiacos conforman las malformaciones congénitas más frecuentes, con una incidencia que se ha estimado entre 4 y 12 por 1000 en recién nacidos vivos. Estos tienen una etiología multifactorial en la que convergen la predisposición genética y los factores ambientales. A partir de 1990 se ha relacionado este tipo de patologías con microdelección 22q11. Se determinó la frecuencia de la microdeleción 22q11 en pacientes con cardiopatía congénita no sindrómica. Se analizaron 61 pacientes con cardiopatía congénita, a partir de ADN de sangre periférica y posterior amplificación, mediante PCR multiplex del gen TUPLE1 y del STR D10S2198, visualización electroforesis en geles de agarosa y análisis densitométrico para determinar dosis génica. Se encontraron 3 pacientes con microdeleción 22q11, para una frecuencia de 4,9%. Esta microdeleción se asoció en dos de los casos a Tetralogía de Fallot y en el otro a Defecto Septal Atrial (DSA). En conclusión, la frecuencia de microdeleción 22q11 en la población analizada es de 4,9%. Dentro de los casos de Tetralogía de Fallot, la microdeleción estaba presente en el 7,4% y en los DSA corresponde al 11,1%.

Cardiac defects are the most frequent congenital malformations, with an incidence estimated between 4 and 12 per 1000 newborns. Their etiology is multifactorial and might be attributed to genetic predispositions and environmental factors. Since 1990 these types of pathologies have been associated with 22q11 microdeletion. In this study, the frequency of microdeletion 22q11 was determined in 61 patients with non-syndromic congenital heart disease. DNA was extracted from peripheral blood and TUPLE1 and STR D10S2198 genes were amplified by multiplex PCR and visualized in agarose gels. Gene content was quantified by densitometry. Three patients were found with microdeletion 22q11, representing a 4.9% frequency. This microdeletion was associated with two cases of Tetralogy of Fallot and a third case with atrial septal defect (ASD). In conclusion, the frequency for microdeletion 22q11 in the population analyzed was 4.9%. The cases that presented Teratology of Fallot had a frequency for this microdeletion of 7.4% and for ASD of 11.1%.

Sequence analysis of the CDKN1B gene in patients with premature ovarian failure reveals a novel mutation potentially related to the phenotype.

Earlier reports demonstrated a key role of Cdkn1b during mouse ovarian development. In this study, the sequencing analysis of the complete coding region of this gene in a panel of premature ovarian failure patients and control subjects reveals a novel mutation potentially related to the phenotype.

[Analysis of microdeletions in 22q11 in Colombian patients with congenital heart disease]. / Análisis de microdeleciones en 22q11 en pacientes Colombianos con cardiopatía congénita no sindrómica.

Cardiac defects are the most frequent congenital malformations, with an incidence estimated between 4 and 12 per 1000 newborns. Their etiology is multifactorial and might be attributed to genetic predispositions and environmental factors. Since 1990 these types of pathologies have been associated with 22q11 microdeletion. In this study, the frequency of microdeletion 22q11 was determined in 61 patients with non-syndromic congenital heart disease. DNA was extracted from peripheral blood and TUPLE1 and STR D10S2198 genes were amplified by multiplex PCR and visualized in agarose gels. Gene content was quantified by densitometry. Three patients were found with microdeletion 22q11, representing a 4.9% frequency. This microdeletion was associated with two cases of Tetralogy of Fallot and a third case with atrial septal defect (ASD). In conclusion, the frequency for microdeletion 22q11 in the population analyzed was 4.9%. The cases that presented Teratology of Fallot had a frequency for this microdeletion of 7.4% and for ASD of 11.1%.

Novel CACNA1S mutation causes autosomal dominant hypokalemic periodic paralysis in a South American family.

Hypokalaemic periodic paralysis (HypoPP) is an autosomal dominant disorder, which is characterized by periodic attacks of muscle weakness associated with a decrease in the serum potassium level. A major disease-causing gene for HypoPP has been identified as CACNA1S, which encodes the skeletal muscle calcium channel alpha-subunit with four transmembrane domains (I-IV), each with six transmembrane segments (S1-S6). To date, all CACNA1S mutations identified in HypoPP patients are located within the voltage-sensor S4 segment. In this study we report a novel CACNA1S mutation in a new region of the protein, the S3 segment of domain III. We characterized a four-generation South American family with HypoPP. Genetic analysis identified a novel V876E mutation in all HypoPP patients in the family, but not in normal family members or 160 control people. Clinical analysis indicates that mutation V876E is associated with a severe outcome as characterized by a very early age of onset, complete penetrance and a severe prognosis including death. These results identify a new mutation in CACNA1S and expand the spectrum of CACNA1S mutations associated with HypoPP.

Análisis de deleciones en 15 exones situados dentro y fuera del hot spot mutacional del gen de la distrofina en pacientes con distrofia muscular de Duchenne / Deletion Analysis of 15 exons located outside and inside a “Hot Spot” in the Duchenne Muscular Dystrophy gene in Duchenne’s Muscular dystrophy patients

Introducción. La distrofia muscular de Duchenne (DMD), y su forma alélica más leve, la distrofia muscular de Becker (DMB), es una entidad de herencia recesiva ligada al X, que se presenta con debilidad muscular, pérdida progresiva de las habilidades motoras y muerte precoz. Es causada principalmente por deleciones en el gen de la distrofina, el cual contiene 79 exones. Objetivo. Realizar un análisis ampliado para evaluar la presencia de deleciones en 15 exones del gen de la distrofina situados dentro y fuera del hot spot mutacional en 58 pacientes afectados con DMD/DMB sin mutación previamente identificada. Metodología. Amplificación, mediante PCR múltiplex, de 4 exones situados dentro y 11 fuera del hot spot mutacional descrito para el gen de la distrofina en 58 pacientes afectados con DMD y determinar la frecuencia de deleciones en la población analizada. Resultados. Se encontró deleción del exón 16 en uno de los pacientes estudiados, hecho que indica una frecuencia de 1,7%. No se observó ninguna deleción de los exones situados fuera del hot spot mutacional. Conclusiones. La frecuencia de deleciones en los 15 exones del gen de la distrofina analizados es baja; sólo se presentó en el exón 16, el cual se encuentra localizado en el hot spot mutacional proximal del gen. Es importante analizar este exón en los afectados, en la medida en que aumenta la tasa de detección de deleciones en un 1,7%. Se debe analizar otro tipo de mutaciones como puntuales y duplicaciones en los afectados.

Introduction. Duchenne and Becker Muscular Dystrophies (DMD/DMB) are X-linked recessive diseases characterized by progressive muscle weakness and wasting, loss of motor skills and death after the second decade of life. Deletions are the most prevalent mutations that affect the dystrophin gene, which spans 79 exons. Objective: Identify deletions on the dystrophin gene in 58 patients affected with DMD. Methods: Through multiplex PCR identify deletions on the dystrophin gene in 58 patients with DMD and observe the frequency of this mutation in our population. Results: We found deletions in 1.72% of patients (1 of 58 persons). Deletions were not the principal cause of disease in our population. It is possible that duplications and point mutations caused this illness in our patients. Conclusions: The frequency of deletions in the 15 exons analyzed from the dystrophin gene was low. The predominant types of mutation in our patients` samples were not deletions as has been observed in the literature worldwide, therefore, it is important to determine other types of mutations as are duplications and point mutations.

Detección de portadoras de distrofia muscular de Duchenne en familias colombianas mediante anßlisis de microsatélites / Carrier detection of Duchenne muscular dystrophy in Colombian families by microsatellite analysis

Introducción: Las distrofias musculares de Duchenne y Becker son enfermedades recesivas ligadas al cromosoma X; la identificación de portadoras se puede hacer por métodos directos cuando se ha identificado la mutación, o por indirectos como el anßlisis de haplotipos. Objetivo: Se busca establecer mediante analisis de STRs y construcción de haplotipos el estado de portadora o no portadora en 37 familias con afectados por DMD/DMB. Metodología: Se estudiaron 174 personas mediante el anßlisis de 10 STRs intra y extragénicos del gen de la distrofina y la construcción de haplotipos para la identificación del ligado a la mutación. Resultados: Con la metodología mencionada se logró determinar el estado de portadora en 89.2% de las mujeres participantes, de las cuales 65.7% eran portadoras y 23.5% no portadoras. Conclusiones: El anßlisis indirecto mediante construcción de haplotipos permitió establecer el estado de portadora en una gran proporción de la población analizada de mujeres y permitió brindar un adecuado asesoramiento genético.

Introduction: The muscular dystrophies of Duchenne and Becker are X-linked recessive neuromuscular disorders; the carrier testing protocols include mutation detection or linkage analysis. Objective: The aim of this investigation was to use the segregation analysis of STR loci to determine the carrier status in 37 families with DMD/DMB. Methods: From 37 families 174 individuals were studied through segregation of 10 intra and extragenic short tandem repeats (STR) in the members of the family. Results: The carrier status of 89.2% women of the tested group could be assigned by linkage analysis, 65.7% carriers and 23.5% non-carriers. Conclusions: Linkage analysis was proven to be a powerful tool for the carrier detection in DMD/BMD and should be taken into account in genetic counselling practice.

Identificación de deleciones en portadoras de distrofia muscular de Duchenne / Deletions identification in female carriers of Duchenne’s muscular distrophy

Objetivos: identificación de mujeres portadoras en familias con afectados por distrofia muscular de Duchenne y Becker (DMD/DMB) mediante construcción de haplotipos y determinación de perdida de heterocigocidad.Introducción: la DMD/DMB es una entidad de herencia recesiva ligada al cromosoma X que se presenta con debilidad muscular, pérdida progresiva de las habilidades motoras y muerte precoz. Son causadas por mutaciones en el gen de la distrofina, el cual contiene 79 exones. Se presentan resultados de dos familias con diagnóstico de DMD/DMB, en las que se había observado previamente deleción en el gen. Se realizó extracción de ADN genómico, seguido de amplificación de 10 STRs, intragénicos y extragénicos del gen de la distrofina, se construyeron haplotipos para los afectados y las mujeres por línea materna en los grupos familiares. Resultados y conclusiones: con los haplotipos y la determinación de pérdida de heterocigocidad se identificó el estado de portadora en mujeres familiares de afectados con deleción, se discute la aplicación de este método para la identificación de portadoras y su implicación en el asesoramiento genético.