Long-range PCR amplification-based targeted enrichment & next generation sequencing: A cost-effective testing strategy for lysosomal storage disorders

Background & objectives: Lysosomal storage disorders (LSDs) are genetic metabolic disorders which result from deficiency of lysosomal enzymes or defects in other lysosomal components. Molecular genetic testing of LSDs is required for diagnostic confirmation when lysosomal enzyme assays are not available or not feasible to perform, and for the identification of the disease causing genetic variants. The aim of this study was to develop a cost-effective, readily customizable and scalable molecular genetic testing strategy for LSDs. Methods: A testing method was designed based on the in-house creation of selective amplicons through long range PCR amplification for targeted capture and enrichment of different LSD genes of interest, followed by next generation sequencing of pooled samples. Results: In the first phase of the study, standardization and validation of the study protocol were done using 28 samples of affected probands and/or carrier parents (group A) with previously identified variants in seven genes, and in the second phase of the study, 30 samples of enzymatically confirmed or biopsy-proven patients with LSDs and/or their carrier parents who had not undergone any prior mutation analysis (group B) were tested and the sequence variants identified in them through the study method were validated by targeted Sanger sequencing. Interpretation & conclusions: This testing approach was found to be reliable, easily customizable and cost-effective for the molecular genetic evaluation of LSDs. The same strategy may be applicable, especially in resource poor settings, for developing cost-effective multigene panel tests for other conditions with genetic heterogeneity.

Utility of morphologic assessment of bone marrow biopsy in diagnosis of lysosomal storage disorders

Introduction: Lysosomal storage disorders (LSDs) are rare disorders and pose a diagnostic challenge for clinicians owing to their generalized symptomatology. In this study, we aim to classify LSDs into two broad categories, namely, Gaucher disease (GD) and Niemann–Pick/Niemann–Pick-like diseases (NP/NP-like diseases) based on the morphology of the storage cells in the bone marrow (BM) aspiration smears and trephine biopsy sections. Materials and Method: This retrospective study includes 32 BM specimens morphologically diagnosed as LSDs at our institute, in the last 10 years. Subsequently, they were subclassified into GD and NP/NP-like diseases. Further, we have compared and analyzed the clinical, hematological, and biochemical parameters for the two groups of LSDs. Results: Based on BM morphology, 59.4% (n = 19) cases were diagnosed as NP/NP-like diseases and 40.6% (n = 13) cases as GD. Abdominal distension and failure to thrive were the most common clinical manifestations in both groups of LSDs. Anemia and thrombocytopenia were frequently seen in either of the LSDs. On the assessment of metabolic profile, elevated total/direct bilirubin and liver enzymes were more commonly seen in NP/NP-like diseases when compared with GD. Conclusion: We have classified LSDs into GD and NP/NP-like diseases based on the morphology of the storage cells in the BM specimen. The hallmark findings on BM biopsy annexed with the comparative features of the two proposed categories can aid the clinician in clinching the diagnosis. Formulation of such a methodology will prove instrumental for patient care in an underresourced setting.

Disease spectrum analysis of 1 520 cases with lysosomal storage disorders / 中华实用儿科临床杂志

Objective:To analyze the disease spectrum of lysosomal storage disorders(LSDs) and explore the prevalent distributions of different LSD types in one center in Shanghai.Methods:A retrospective analysis was made.A total of 5 476 suspected LSD patients, including 3 415 males and 2 061 females, with a median age of 4 years(1 day to 72 years), were collected from Xinhua Hospital, Shanghai Jiaotong University School of Medicine from August 2008 to May 2022.The activity of different lysosomal enzymes was detected by fluorescent and biochemical methods.Results:A total of 1 520 patients were diagnosed with LSDs, including 972 males and 548 females, with a median age of 4 years(1 day to 59 years), involving 19 different subtypes.Mucopolysaccharidosis(MPS) was the most common type among LSDs, with a frequency of 45.46%(691/1 520), followed by sphingolipidoses [33.88%(515/1 520)] and glycogen storage disease type Ⅱ [16.05%(244/1 520)] successively.MPS Ⅱ was the most common type in MPS, with a frequency of 45.73%(316/691), followed by MPS ⅣA [22.87%(158/691)]. Niemann-Pick A/B, Gaucher, and Krabbe diseases were common in Sphingolipidoses patients, with frequencies of 37.09%(191/515), 34.37%(177/515), and 10.29%(53/515), respectively.Conclusions:LSDs are common genetic metabolic diseases, especially MPS and sphingolipidoses.Newborn screening for LSDs should be carried out timely so that the patients can be treated early and their prognosis can be improved.

Expression, purification and functional verification of recombinant human α-galactosidase A in suspension CHO-S / 中国药理学通报

Aim To express and purify rhα-Gal A with a 6 X His tag via using a serum-free expression system in high-density suspension culture of Chinese hamster ovary cells ( CHO-S) , and to verify the scavenging effect of rhα-Gal A on globular trisaccharide ceramide (Gb3 or GL3) . Methods The construction of recombinant protein expression vector, pcDNA4-GLA, was achieved by fusing the human α-galactosidase cDNA, gla, with 6 X His tag and artificial DNA synthesis. The expression plasmid was transfected into the suspended CHO-S to express rhα-Gal A and then purified. Following this procedure, we determined rhα-Gal A's expression, the enzymatic activity, and the glycosylation of the recombinant enzyme. Co-incubation with cultured cells was performed to examine whether rhα-Gal A could be taken up into the cells and effectively remove Gb3 substrates. Results rhα-Gal A was successfully expressed and purified after transiently transfecting pcDNA4-GLA into the suspended CHO-S, and the yield was up to (100 ±20. 6) mg • L

Hurler Syndrome: a Biochemically Confirmed Case in Dominican Republic

Abstract Mucopolysaccharidosis (MPS) is a group of metabolic disorders caused by the deficiency or complete absence of certain lysosomal enzymes responsible for the breakdown of mucopolysaccharides, causing an accumulation of glycosaminoglycans (GAGs) throughout the body. Mucopolysaccharidosis type I (MPS I), also called Hurler syndrome, is an autosomal recessive lysosomal storage disorder resulting from a deficiency of the enzyme α-L-iduronidase. This report aims to present the clinical findings and diagnosis of a 21-month-old female with no history of similar cases in their previous generations. The diagnosis was considered based on the clinical and radiological characteristics of Hurler syndrome (HS) and confirmed biochemically, becoming the first confirmed case in the Dominican Republic.

Clinical Profile Among Brazilian Mucopolysaccharidosis type II Patients: Subgroup Analysis from the Hunter Outcome Survey

Abstract Mucopolysaccharidosis type II (MPS II) is a rare genetic, multiorgan disease. Little information about the Brazilian context is available to date; thus, this descriptive subgroup analysis was conducted on Brazilian data from the Hunter Outcome Survey (HOS), including clinical characteristics among MPS II patients from Brazil. HOS is a global, multi-center, long-term, observational registry of patients with MPS II (NCT03292887). Variables related to organ system involvement, signs and symptoms, surgical procedures and survival among Brazilian patients were extracted from HOS database. Data from 153 Brazilian patients with MPS II were analyzed. Musculoskeletal (96.6%), abdomen/gastrointestinal (95.2%), neurological (88.7%), pulmonary (86.2%), and ear (81.3%) were the most frequently observed organ/systems involved. Regarding signs and symptoms, the most prevalent symptom was coarse facial features consistent with the disease (94.6%), followed by joint stiffness and limited function (89.3%), hernia (84.2%) and hepatomegaly (82.2%). Median survival time was 22.0 years, and the major cause of death was respiratory failure (31.8%). These data may be helpful to understand disease characteristics and to help improve the quality of MPS II patient care in Brazil.

Hallazgos ecocardiográficos de pacientes pediátricos con mucopolisacaridosis tipo IV-A con mutación c.901G>T en el gen GALNS en un centro de salud de cuarto nivel de Colombia en el periodo de 2012-2019

La mucopolisacaridosis tipo IV-A es un trastorno de almacenamiento lisosómico poco frecuente, cuya manifestación clínica más evidente es la disostosis múltiple. Alteraciones multiorgánicas se han descrito en este tipo de pacientes, sin embargo, las manifestaciones cardiovasculares no han sido descritas con gran énfasis. Esta investigación tuvo como objetivo principal describir los hallazgos ecocardiográficos en pacientes pediátricos con mucopolisacaridosis tipo IV-A con mutación c.90iG>T en el gen GALNS. Se realizó un estudio descriptivo de serie de casos que incluyó pacientes con diagnóstico confirmado (clínico, bioquímico y molecular) de mucopolisacaridosis tipo IV-A; los pacientes asistieron a una institución hospitalaria en Pereira, Colombia, entre 2012 y 2019, donde se valoraron parámetros ecocardiográficos. Se incluyeron diez pacientes con edades comprendidas entre 3 y 18 años, media de 10. Las anomalías cardiacas identificadas fueron regurgitación mitral trivial RM en 4 de 10 pacientes, dilatación del anillo aórtico en 9 de 10, dilatación de la aorta ascendente, dilatación del arco transverso y del istmo aórtico en 1 de 10, área subaórtica levemente engrosada sin estenosis e hipertrofia ventricular izquierda concéntrica leve en 1 de 10 pacientes. La función ventricular fue normal en todos los pacientes. Los hallazgos ecocardiográficos más frecuentes fueron dilatación del anillo aórtico y regurgitación trivial de la válvula mitral, adicionalmente, pueden encontrarse válvulas mitral y aórtica engrosadas e hipertrofia ventricular izquierda, por lo que es importante una valoración periódica por cardiología pediátrica.

Mucopolysaccharidosis IV-A is a rare lysosomal storage disorder, whose most evident clinical manifestation is multiple dysostosis. Multiorgan disorders have been described in this type of patients, however, the Cardiovascular manifestations have not been described with greater emphasis. The main objective of this research was to describe the echocardiographic findings in pediatric patients with type IV-A mucopolysaccharidosis with c.901G>T mutation in the GALNS gene. A descriptive case series study was carried out, which included patients with a confirmed diagnosis (clinical, biochemical and molecular) of mucopolysaccharidosis type IV-A; the patients were attended a hospital institution in Pereira, Colombia, between 2012 and 2019, where echocardiography parameters were evaluated. Ten patients with ages ranging from 3 to 18 years, average 10, were included. The cardiac abnormalities identified were trivial mitral regurgitation in 4 of 10 patients, aortic annulus dilation in 9 of 10, dilatation of the ascending aorta, dilatation of the transverse arch and aortic isthmus in 1 of 10, slightly thickened subaortic area without stenosis and mild concentric left ventricular hypertrophy in 1 of 10 patients. Ventricular function was normal in all patients. The most frequent echocardiography findings were dilatation of the aortic annulus and trivial regurgitation of the mitral valve, additionally, thickened mitral and aortic valves and left ventricular hypertrophy may be found, so periodic evaluation by pediatric cardiology is important.

MUCOPOLYSACCHARIDOSIS TYPE 2: NARRATIVE REVIEW

Mucopolysaccharidosis type II, also known as Hunter syndrome, is a rare, progressive, multisystemic lysosomal storage disease caused by de?ciency of iduronate 2 sulfatase, an enzyme responsible for the degradation of the mucopolysaccharides dermatan (DS) and keratan sulfate (QS), causing their accumulation at the lysosomal level. It is an X-linked disease, therefore it is common to ?nd most cases in men, rarely in women, it is considered an orphan disease given an incidence of approximately 1/100,000 live births. Various phenotypes of severe (2/3) and attenuated disease have been described. The diagnosis is based on clinical ?ndings and the measurement of mucopolysaccharides DS and QS in urine, which are elevated, con?rmed by determining the enzyme de?ciency in serum, leukocytes and ?broblasts. It has been observed that in patients with enzyme replacement therapy somatic symptoms have decreased, however there are several studies of alternative therapies in the future, including gene therapy as an alternative in the future

Coexistencia infrecuente de la enfermedad de Tay-Sachs, coartación aórtica y reflujo vesicoureteral de grado V / Rare coexistence of Tay-Sachs disease, coarctation of the aorta and grade V vesicoureteral reflux

La enfermedad de Tay-Sachs es una enfermedad metabólica hereditaria neurodegenerativa. Existen cuatro tipos según el inicio de los síntomas clínicos: infantil, infantil de inicio tardío, juvenil y adulto. El tipo infantil tiene el peor pronóstico. Recientemente, se describieron diferentes anomalías que acompañan a los trastornos metabólicos e influyen en el pronóstico. Presentamos el caso de un lactante con enfermedad de Tay-Sachs junto con coartación aórtica y reflujo vesicoureteral bilateral (RVU) de grado V. Se realizó el seguimiento del paciente en el consultorio externo de Cardiología Pediátrica. En la ecografía abdominal, se observó ectasia pielocalicial, y se detectó reflujo vesicoureteral bilateral de grado V en la cistouretrografía miccional. No se ha informado previamente la coexistencia de estas anomalías. Este caso pone de manifiesto que no se deben subestimar las anomalías del examen neurológico en los pacientes con una cirugía cardíaca reciente, porque podría perderse la oportunidad de diagnosticar enzimopatías congénitas.

Tay-Sachs disease is a neurodegenerative inherited metabolic disease. There are four forms classified by the time of first clinical symptoms: infantile, late infantile, juvenile and adult. Infantile form has the poorest prognosis. Lately, different abnormalities which accompany metabolic disorders and affect the prognosis have been described. We present an infant with Tay-Sachs disease accompanied by coarctation of the aorta and bilateral grade V vesicoureteral reflux (VUR). The patient was followed up in the outpatient clinic of Pediatric Cardiology. The abdominal ultrasonography showed pelvicalyceal ectasia; bilateral grade V VUR in voiding cystourethrography was found. This coexistence has not been previously reported. This case emphasizes that abnormalities in the neurological examination of cardiac postsurgical patients should not be underestimated because the opportunity to diagnose inborn errors of metabolism could be missed.

Hearing Impairment in Mucopolysaccharidosis: A Systems Biology Approach

Abstract Mucopolysaccharidoses (MPS) are lysosomal diseases caused by deficiencies in lysosomal enzymes involved in the degradation of glycosaminoglycans (GAGs). Sensorineural hearing impairment is a common feature in MPS patients, but there is no consensus on its etiology. For this reason, we aimed to identify genes and pathways related to hearing loss and to correlate them with gene expression data in MPS. We used HPO and Disgenet to identify candidate genes. We constructed the network with string and Cytoscape, and hub genes were identified in Cytohubba. Expression data were obtained from the MPSBase website. We found the NDUFA gene family as the major hub genes and 114 enriched pathways related to hearing loss. These genes and biological pathways may serve as potential candidates for clinical studies to better understand hearing impairment mechanisms in lysosomal storage diseases like mucopolysaccharidosis.

CLN6 Variant of Late Infantile Neuronal Ceroid Lipofuscinosis Caused by a Homozygous Mutation: Case Report in Colombia

Abstract Introduction: Neuronal ceroid lipofuscinosis (NCLs) is an autosomal recessive neurodegenerative disorders group. We report the first case in Colombia involving a new genetically confirmed variant of a homozygous CLN6 mutation. Case report: 12-year-old male, history of blood parents and average growth until 5 years of age. At this age began focal crises, progressive regression of neurodevelopment, severe cognitive deficit, and swallowing disorder that led to gastrostomy. Clinical exome + CNVs + mitochondrial DNA genetic study identified variant NM_017882.3 (CLN6): c. 22C>T, p. (Gln8*) in homozygous, deleterious. Late-onset infantile neuronal ceroid lipofuscinosis was diagnosed. Discussion: Mutations in the CLN6 gene are associated with late-onset infantile lipofuscinosis of autosomal recessive inheritance. This variant has not been previously described in the medical literature nor is it listed in the population databases, which indicates that it is extremely rare. The treatment focuses on the control of seizures, sleep disturbances, extrapyramidal symptoms, behavioral disorders, anxiety, and psychosis. Conclusion: To date, this variant of the CLN6 gene has not been reported in the world. There are currently no etiological or disease-specific therapeutic approaches. The use of exome/whole genome sequencing can be very useful for etiological diagnosis and differential diagnosis. An early diagnosis opens the door to future care and treatment.

Incidencia de la enfermedad de Fabry en pacientes con enfermedad renal crónica atendidos en tres centros de salud del departamento de Atlántico, Colombia. 2017-2018

Introducción: la enfermedad de Fabry es un defecto lisosomal caracterizado por una alteración de la enzima alfa-galactosidasa y que produce el acúmulo de glucoesfingolípidos en diferentes tejidos. Este defecto enzimático está ligado al cromosoma X y por ende es más frecuente en hombres. Sus manifestaciones clínicas varían de acuerdo al grupo etario afectado e incluyen lesiones en piel, anhidrosis, opacidades corneales, crisis de dolor, daño renal, entre otros. Objetivo: calcular la incidencia de enfermedad de Fabry en pacientes con diagnóstico de enfermedad renal crónica (ERC). Materiales y métodos: estudio ambispectivo realizado en los pacientes con diagnóstico de ERC que asistían a controles médicos en tres centros de prevención renal ubicados en el departamento del Atlántico, Colombia, y que además cumplían los criterios de inclusión y exclusión. Se revisaron las historias clínicas y se tomaron muestras para confirmar la presencia de enfermedad de Fray. Resultados: se identificaron 471 pacientes con ERC y se estableció una incidencia global de 21,23 casos por cada 1.000 habitantes para baja actividad de la alfa-galactosidasa. Sin embargo, solo en el 20% se confirmó la presencia de enfermedad de Fray mediante pruebas genéticas. Conclusiones: la incidencia de la enfermedad de Fabry en la población estudiada es mayor a la reportada en otras cohortes y además fue más frecuente en el sexo femenino.

Introduction: Fabry's disease consists of a lysosomal defect linked to the X chromosome that produces the accumulation of glycosphingolipids in different tissues. The clinical manifestations depend on the age of presentation, and includes skin lesions, acroparesthesia, pain crisis, anhidrosis, corneal opacities and hearing loss, among others. Objectives: Calculate the incidence of Fabry disease in patients diagnosed with chronic kidney disease Methodology: An ambispective study was designed, including all patients diagnosed with chronic kidney disease under medical control in three renal prevention centers located in the department of Atlántico, and which also met the inclusion and exclusion criteria. Subsequently, the review of the medical records and the sampling were carried out. Results: A total of 471 patients with chronic kidney disease were identified, with an overall incidence of 21.23 cases per 1000 people. However, only 20% were confirmed by genetic tests. Conclusions: The incidence of Fabry disease in the population studied is greater than that reported in other cohorts. In addition, it is more frequent in the female sex.

Review and Proposal of Alternative Technologies for Comprehensive and Reliable Newborn Screening Using Paper Borne Urine Samples for Lysosomal Storage Disorders: Glycosphingolipid Disorders

Abstract Few current methods are efficient to detect a high number of lysosomal storage disorders (LSDs) in newborn screening. Therefore, we propose a stepwise procedure that starts with the use of paper borne urine samples (Berry-Woolf specimen) for the inexpensive detection of elevated lysosomal content and the identification of which of the three majors biochemical groups -mucopolysaccharides, oligosaccharides, and glycosphingolipids- is detected. Urine samples are preferable to blood samples because of their higher concentrations of the relevant analytes. Subsequent steps would precisely determine which enzyme deficiency is involved. As a summary, following our previous papers on the detection of elevated oligosaccharides and mucopolysaccharides, here we describe how elevated urinary glycosphingolipids (GSLs) could be fluorometrically detected using the reagent 5-hydroxy-1-tetralone (HOT) and subsequently identified with precision by continuous thin layer chromatography or other techniques. We also outline the steps required for the validation of this procedure for its introduction in newborn screening programs.

Molecular Characterization of the GBA Gene in Patients from Southwest of Colombia with Gaucher Disease

Abstract Introduction Gaucher's disease (GD) is an autosomal-recessive lysosomal storage disorder that results from hereditary deficiency of the acid glucocerebrosidase enzyme, encoded by the GBA gene necessary for the degradation of glucosylceramide. Objective molecularly characterize the variants found in the GBA gene present in patients from the Southwest of Colombia with GD. Material and methods 19 patients were included in the study, clinically and enzymatically diagnosed with GD. A molecular analysis of the GBA gene was performed and the variants were subsequently searched in different population and clinical databases. A bioinformatic analysis was performed. Results The variants in the GBA gene reported were classified into: 14/19 homozygous patients, 4/19 compound heterozygote and 1/19 heterozygous. The presence of 7 variants coding for 8 different genotypes was reported. Also the known mutations like Asn409Ser, p.Leu483Pro, p.Lys237Glu, p.Glu427Lys, and p.Arg535His were identified in these patients. The most frequent genotype was p. Asn409Ser / Asn409Ser (36%). All the variants presented a pathogenic clinical significance. Conclusion The given study will make it possible to understand the susceptibility to GD in the population. This can help maintain the health quotient of the population through premarital counseling and therefore minimize the burden of disease among the population.

Determination of the Population Allelic Frequency of the Variants of the MPS Complex in Southwestern Colombia

Abstract Mucopolysaccharidoses are lysosomal storage diseases characterized by the excessive accumulation of glycosaminoglycan sulfate in organs and tissues. To determine the population allelic frequency of the MPS complex variants in a population without clinical and molecular diagnosis of MPS. An observational descriptive study was carried out where the allelic frequency of variants presents in the IDUA, IDS, SGSH, NAGLU, HGSNAT, GNS, GALNS, GLB1, ARSB, GUSB, HYAL1 genes was determined by means of the sequencing of 320 exomes from patients without a clinical diagnosis of MPS; the results were tabulated, and allelic frequency formulas were used to determine the values associated with each of the genes. 509 alleles associated with the MPS complex were reported, of which 262 have not been previously reported. Genes with the most frequent allelic presence were IDUA, GLB1 and GALNS, involved in MPS I and MPS IV A / B. The total frequencies ranged between 0.00393 (2 alleles) and 0.47937 (248 alleles). These studies make it possible to determine polymorphisms that circulate in the country, present in patients not affected with MPS, allowing to expand the knowledge about the characteristics of the alleles that are present in affected patients.

Depression: The Hidden Problem in Fabry Disease. A Review

Abstract Fabry disease (FD) is an X-linked disorder of glycosphingolipids caused by mutations of the GLA gene. The classical form presents with neuropathic pain and gastrointestinal complaints since childhood or adolescence and progressing into adulthood with ischemic stroke, cardiac dysfunction, and chronic kidney disease. Depression seems to be a frequent complication of FD but its frequently underdiagnosed and undertreated. Comorbid depression in different chronic diseases has been associated with an overall increase in disease burden and medical costs, impairment in activities of daily living, and impact on self-care and treatment adherence. In addition, a clear association between pain and depression has been observed in FD patients and appears to have an unequivocal neurobiological matrix. The aim of this review is to provide an overview of the literature on depression in patients with FD and to highlight some of the emerging issues on this topic. Further research to improve detection and to develop effective treatments for depression in this population is promptly needed.

GM1 gangliosidosis: a case report / Gangliosidose GM1: um relato de caso

RESUMEN La gangliosidosis GM1 es un trastorno lisosomal caracterizada por la acumulación de gangliósido GM1 (glucoesfingolípido) en el sistema nervioso central (SNC) y visceral, debido a la deficiencia de la enzima beta-galactosidase (hidrolasa lisosomal). Afecta principalmente al SNC y las vísceras y produce importantes anomalías esqueléticas, que a menudo ocurren con la presencia de linfocitos vacuolados en la muestra de la sangre periférica o médula ósea. Tiene tres formas de presentación, lo que dificulta aún más su identificación debido al amplio espectro clínico. El presente estudio tiene como objetivo describir un caso de gangliosidosis GM1 en un paciente masculino, nacido a las 38 semanas. Hasta el momento, no existe un tratamiento efectivo para la gangliosidosis GM1, es decir, el portador de la enfermedad solo recibe medidas sintomáticas y paliativas. Por tanto, el diagnóstico precoz de la enfermedad es de suma importancia, ya que su única forma de prevención, actualmente, es a través del consejo genético.

Clinical Manifestation in Females with X-linked Metabolic Disorders: Genetic and Pathophysiological Considerations

Abstract Inborn errors of metabolism are predominantly autosomal-recessive disorders, but several follow an X-linked pattern of inheritance. They are called X-linked recessive, if the female carriers are asymptomatic, and are called X-linked dominant disorders, if almost all females are affected. Conditions, in which some females have symptoms while others are asymptomatic lifelong are simply referred to as X-linked. The aim of this review is to point out the variability in clinical manifestation of affected females in some X-linked metabolic disorders and to discuss on the basis of these examples possible mechanisms that may explain the broad phenotypic spectrum, such as the type of the underlying mutation, the issue of autonomous versus non-autonomous gene expression and the degree of skewing of X-inactivation. The use of the terms "X-linked dominant" and "X-linked recessive" will be discussed.

A Case Report on the Challenging Diagnosis of Neuronal Ceroid Lipofuscinosis Type 2 (CLN2)

Abstract Neuronal ceroid lipofuscinoses (NCLs), also referred as "Batten disease", are a group of thirteen rare genetic conditions, which are part of the lysosomal storage disorders. CLN type 2 (CLN2) is caused by the deficient activity of the tripeptidyl peptidase I (TPP1) enzyme, encoded by the TPP1 gene, most frequently leading to the classic late infantile phenotype. Nearly 140 CLN2-causing mutations have been described. In this case report, we describe the identification of a new disease-causing mutation and highlight the importance of appropriate laboratory investigation based on clinical suspicion. The collection of dried blood spots (DBS) on filter paper, which is a convenient sample, can be used to measure the TPP1 enzyme activity and detect CLN2-related mutations. Since the biochemical and genetic diagnoses are possible and as the disease progression is fast and the therapeutic window is short, the investigation of CLN2 should be always considered when this diagnostic hypothesis is raised in order to enable the patients to benefit from the specific pharmacological treatment.

Variantes del gen GBA en el Suroccidente Colombiano / Variants of the GBA gene in the Southwest of Colombia

Introducción: La Enfermedad de Gaucher (EG) es un trastorno genético autosómico recesivo, causado por la deficiencia de la enzima B-Glucocerebrosidasa acida (GBA). En Colombia se ha estimado una prevalencia de 1:266.441 habitantes. Sin embargo, el país no cuenta con datos exactos sobre la incidencia, prevalencia y carga poblacional de esta enfermedad. Objetivo: Con el objetivo de caracterizar molecularmente las variantes encontradas en el gen GBA presentes en pacientes del Suroccidente Colombiano con enfermedad de Gaucher. Materiales y métodos: Se incluyeron 19 pacientes en el estudio, 57,8% de género masculino, con intérvalo de edad entre 4 y 71 años, diagnosticados clínica y enzimáticamente con EG. Se realizó un análisis molecular del gen GBA y posteriormente se buscaron las variantes en diferentes bases de datos poblacionales y clínicas; además se realizó análisis bioinformático para evaluar el posible impacto de las variantes de interés en la estructura y funcionalidad de la proteína. Resultados: Se encontraron 14/19 pacientes homocigotos; 4/19 heterocigotos compuestos y 1/19 heterocigotos). Se reportó la presencia de 7 variantes que codifican para 8 genotipos diferentes. El genotipo más frecuente es p.Asn409Ser/p.Asn409Ser (36%). De las 7 variantes encontradas, se reportó que específicamente p. Asn409Ser (10/23 alelos) y p.Leu483Pro (3/23 alelos) y p.Lys237Glu (3/23 alelos), están presentes en el 69,5% de los alelos. Todas las variantes presentaron una significancia clínica patogénica. Conclusiones: Este trabajo contribuye al establecimiento de las bases moleculares de la EG en los pacientes del Suroccidente Colombiano, permitiendo realizar una correlación genotipo-endotipo-fenotipo. Así mismo, se determina que los algoritmos de diagnóstico que incluyen análisis molecular y herramientas predictivas bioinformáticas permiten mejorar el diagnóstico, el tratamiento y el pronóstico de los pacientes afectados por EG, generando un impacto positivo en el seguimiento de los afectados, de la mano de una correcta consejería genética y estudios de portadores.

Introduction:Gaucher's disease (EG) is an autosomal recessive genetic disorder, caused by a deficiency of the acid B-Glucocerebrosidase (GBA) enzyme. In Colombia, a prevalence of 1: 266.441 inhabitants have been estimated. However, the country does not have exact data on the incidence, prevalence and population burden of this disease. Objective: molecularly characterize the variants found in the GBA gene present in patients from the Southwest of Colombia with Gaucher disease. Material and methods: 19 patients were included in the study, 57,8% male, with an age range between 4 and 71 years, clinically and enzymatically diagnosed with GD. A molecular analysis of the GBA gene was performed and the variants were subsequently searched in different population and clinical databases; In addition, a bioinformatic analysis was performed to evaluate the possible impact of the variants of interest on the structure and functionality of the protein. Results: 14/19 homozygous patients were found; 4/19 compound heterozygotes and 1/19 heterozygotes). The presence of 7 variants coding for 8 different genotypes was reported. The most frequent genotype was p.Asn409Ser/p.Asn409Ser (36%). Of the 7 variants found, it was reported that specifically p. Asn409Ser (10/23 alleles) and p.Leu483Pro (3/23 alleles) and p.Lys237Glu (3/23 alleles), are present in 69,5% of the alleles. All the variants presented a pathogenic clinical significance. Conclusion: This work contributes to the establishment of the molecular bases of GD in patients from the Southwest of Colombia, allowing a genotype-endotype-phenotype correlation to be carried out. Likewise, it is determined that diagnostic algorithms that include molecular analysis and bioinformatic predictive tools allow improving the diagnosis, treatment and prognosis of patients affected by GD, generating a positive impact on the follow-up of those affected, hand in hand with correct genetic counseling and carrier studies.