Consideraciones éticas y científicas del inicio de la vida sobre el aborto eugenésico en enfermedades genéticas incapacitantes en Perú

El artículo expone conceptos actuales biológicos, así como algunos planteamientos filosóficos acerca del inicio de la vida, que se examinarán en relación con la necesidad del aborto eugenésico. Se presenta el concepto de "exdurantismo", en el que la combinación del nuevo genoma nuclear y mitocondrial hacen único al individuo; además, se concibe al complejo genómico como "integrador somático" que dirige el desarrollo embrionario, y se muestra la problemática en el caso de las violaciones que provocan embarazos, el aborto eugenésico en enfermedades genéticas incapacitantes o la utilización de embriones posterior a la fertilización in-vitro. Se plantea que la dignidad de la persona comienza desde la concepción. Frente a la detección de una enfermedad genética, grave o letal, se debe ofrecer soporte económico y social, de diagnóstico y tratamiento; además, desde la salud pública, una mayor inversión para plantear estrategias de tamizaje, diagnóstico, manejo e investigación.

The article presents current biological concepts, as well as some philosophical approaches to the beginning of life, which will be examined in relation to the need for eugenic abortion. The concept of "exdurantism" is presented, in which the combination of the new nuclear and mitochondrial genome makes the individual unique; furthermore, the genomic complex is conceived as a "somatic integrator" that directs embryonic development, and the problematic is shown in the case of rape that causes pregnancies, eugenic abortion in incapacitating genetic diseases or the use of embryos after in-vitro fertilization. The dignity of the person begins at conception. When a serious or lethal genetic disease is detected, economic and social support, diagnosis and treatment should be offered; in addition, public health should invest more in screening, diagnosis, management and research strategies.

O artigo apresenta conceitos biológicos atuais, bem como algumas abordagens filosóficas sobre o início da vida, que serão examinados em relação à necessidade do aborto eugênico. É apresentado o conceito de "exdurantismo", no qual a combinação do novo genoma nuclear e mitocondrial torna o indivíduo único; além disso, o complexo genômico é concebido como um "integrador somático" que dirige o desenvolvimento embrionário, e é mostrada a problemática no caso de estupro que resulta em gravidez, aborto eugênico em doenças geneticamente incapacitantes ou o uso de embriões após a fertilização in vitro. Argumenta-se que a dignidade da pessoa começa na concepção. Diante da detecção de uma doença genética, grave ou letal, devem ser oferecidos apoio econômico e social, diagnóstico e tratamento, bem como maior investimento em saúde pública em estratégias de triagem, diagnóstico, gestão e pesquisa.

A Case Report of Fanconi Anemia: A Literature Review and Dental Perspective of Rare Disease

Introduction: Fanconi Anaemia (FA) is a very rare genetic disease characterised by genetic alterations, which causes con- genital abnormalities in individuals. This clinical case report of Fanconi anaemia, will review classical signs of the disease in detail. The various aspects of this rare condition are examined, with an emphasis on oral manifestations and their impact on af- fected patients overall health. Since this group is more likely to acquire cancers, paediatric dentists must be aware of common oral symptoms and possibly malignant lesions in order to make an early diagnosis and provide thorough care and maintenance of oral health to those who are affected. Case Presentation: A four-year-old female patient was brought by her parents to the Department of Pediatric and Preventive Dentistry, Yenepoya Dental college, with a chief complaint of pain in the upper back tooth region. The child had already been diagnosed with FA. Conclusion: Patients with FA are more prone to get infections, so proper precautions should be taken to avoid any situation that might put them at risk of infection or bleeding. Patients should be motivated to have regular follow-ups and encourage them to maintain good periodontal health, to help prevent the incidence of caries and to monitor their overall oral wellbeing.

Neurofibromatosis tipo 1 o enfermedad de Von Recklinghausen. Presentación de caso

La neurofibromatosis tipo I o enfermedad de Von Recklinghausen es una de las enfermedades genéticas que afectan el sistema nervioso, denominada así por su origen común embrionario. Es una enfermedad autosómica dominante, progresiva, de evolución impredecible, que afecta la piel y el sistema nervioso central y periférico. Se presenta el caso de una escolar, femenina, de siete años de edad que ingresó en el Hospital Pediátrico Paquito Gonzáles Cueto debido a la presencia de varias manchas en la piel color "café con leche". Se recogió como antecedente familiar la presencia de neurofibromatosis tipo 1 en la abuela y bisabuela materna, esta última ya fallecida por dicha causa. Al examen físico se constataron nódulos de Lisch en espesor del iris del ojo izquierdo. Los estudios de imágenes evidenciaron varias lesiones nodulares hiperintensas en T2 y FLAIR, a nivel de la cápsula interna y externa bilateral y ventricular izquierda, la mayor de 20 x 11 mm, así como imagen hipointensa a nivel del nervio óptico izquierdo, de 7 mm. Se diagnosticó como neurofibromatosis tipo I. Por ser una de las enfermedades menos estudiadas en nuestro medio se decidió la publicación de este caso.

Neurofibromatosis type I or Von Recklinghausen's disease is one of the genetic diseases that affect the nervous system, named for its common embryonic origin. It is an autosomal dominant, progressive disease with an unpredictable course that affects the skin and the central and peripheral nervous system. The case of a seven-year-old female schoolchild who was admitted to the Paquito Gonzáles Cueto Pediatric Hospital due to the presence of several "coffee-with-milk" spots on her skin is presented. The presence of type 1 neurofibromatosis in her maternal grandmother and great-grandmother, the latter already deceased from said cause, was collected as a family history. On physical examination, Lisch nodules were found in the thickness of the iris of the left eye. Imaging studies revealed several hyperintense nodular lesions on T2 and FLAIR, at the level of the internal and external bilateral and left ventricular capsule, the largest measuring 20 x 11 mm, as well as a hypointense image at the level of the left optic nerve, measuring 7 mm. It was diagnosed as neurofibromatosis type I. Because it is one of the least studied diseases in our environment, it was decided to publish this case.

Progresses on RNA-based therapeutics for genetic diseases / 浙江大学学报·医学版

RNA therapeutics inhibit the expression of specific proteins/RNAs by targeting complementary sequences of corresponding genes, or synthesize proteins encoded by the desired genes to treat genetic diseases. RNA-based therapeutics are categorized as oligonucleotide drugs (antisense oligonucleotides, small interfering RNA, RNA aptamers), and mRNA drugs. The antisense oligonucleotides and small interfering RNA for treatment of genetic diseases have been approved by the FDA in the United State, while RNA aptamers and mRNA drugs are still in clinical trials. Chemical modifications are applied to RNA drugs, such as pseudouridine modification of mRNA, to reduce immunogenicity and improve the efficacy. The secure and effective delivery systems like lipid-based nanoparticles, extracellular vesicles, and virus-like particles are under development to address stability, specificity, and safety issues of RNA drugs. This article provides an overview of the specific molecular mechanisms of 11 RNA drugs currently used for treating genetic diseases, and discusses the research progress of chemical modifications and delivery systems of RNA drugs.

Clinical practice of whole-genome sequencing in the rapid diagnosis of critically ill neonates / 中国当代儿科杂志

OBJECTIVES@#To explore the application of whole-genome sequencing (WGS) in the rapid clinical diagnosis of critically ill neonates.@*METHODS@#The critically ill neonates who admitted to the neonatal intensive care unit of Children's Hospital of Fudan University and underwent WGS from August to September, 2019 were enrolled in this prospective study. The genetic testing results and clinical outcome were analyzed with reference to the sequencing data and clinical features of the neonates.@*RESULTS@#A total of 15 neonates were tested, among whom there were 9 boys and 6 girls. The main reason for hospitalization included abnormal breathing in 7 neonates, poor response in 2 neonates, feeding difficulty in 2 neonates, fever in 1 neonate, hypothermia in 1 neonate, preterm birth in 1 neonate, and convulsion in 1 neonate. The mean turn-around time was 4.5 days for WGS. Finally a genetic diagnosis was obtained for 3 neonates, with a positive diagnostic rate of 20% (3/15). Among the 3 neonates, 2 neonates were withdrawn from the treatment due to severe conditions and 1 neonate died on the day when the sample was sent for genetic testing, whose etiology could be explained by the results of genetic testing.@*CONCLUSIONS@#WGS technique can provide a timely and effective diagnosis for critically ill neonates suspected of genetic diseases and provide genetic evidence for clinical treatment of critically ill cases.

Dental anomalies in syndromes displaying hypertrichosis in the clinical spectrum

Abstract Hypertrichosis and dental anomalies may occur alone or in combination in the spectrum of many syndromes. To identify genetic entities characterized by hypertrichosis and dental anomalies, a search was performed in the Mendelian Inheritance in Man database with the terms "hypertrichosis" or "hirsutism" and "tooth" or "dental abnormalities." Nondependent androgen metabolism disturbances were classified as hypertrichosis. Genetic entities with hypertrichosis and dental anomalies were included in the study. Additional searches were performed in the PubMed and Orphanet databases, when necessary, in order to include data from scientific articles. An integrative analysis of the genes associated with the identified syndromes was conducted using STRING to characterize biological processes, pathways, and interactive networks. The p-values were subjected to the false discovery rate for the correction of multiple tests. Thirty-nine syndromes were identified, and dental agenesis was the most frequent dental anomaly present in 41.02% (n = 16) of the syndromes. Causative genes were identified in 33 out of 39 genetic syndromes. Among them, 39 genes were identified, and 38 were analyzed by STRING, which showed 148 biological processes and three pathways that were statistically significant. The most significant biological processes were the disassembly of the nucleosome (GO:0006337, p = 1.09e-06), chromosomal organization (GO:0051276, p = 1.09e-06) and remodeling of the chromatin (GO: 0006338, p = 7.86e-06), and the pathways were hepatocellular carcinoma (hsa05225, p = 5.77e-05), thermogenesis (hsa04714, p = 0.00019), and cell cycle (hsa04110, p = 0.0433). Our results showed that the identification of hypertrichosis and dental anomalies may raise the suspicion of one of the thirty-nine syndromes with both phenotypes.

Genetic analysis of a female child family with suspected X-linked recessive genetic disease / 中国热带医学

@#Objective　Genetic analysis was performed on a female child with chromosome Xq28 heterozygous deletion and suspected X-linked recessive disease to determine the morbidity and prognosis. Methods　A female child was admitted to the hospital on day 20 because of "jaundice for 20 days and difficulty in stopping bleeding at acupuncture sites". Low depth whole genome test of amniocentesis in late pregnancy suggested missing copy number of hemophilia A and X-linked mental retardation type 72. In order to further confirm the diagnosis and prognosis, peripheral blood of the children and their parents were collected for gene testing, chromosome inactivation test and genetic analysis. Results　Chromosome Xq28 of the child had 439.4 kb copy number heterozygous deletion variation, which was a clear disease-coding gene for functional loss included in ClinGen database. Chromosome inactivation test showed that the paternal X chromosome of the child was extremely inactivated. Haplotype analysis suggested that the normal chromosome of the subject was inherited from the mother, and there was heterozygous deletion on the paternal X chromosome, so it was inferred that the child will not develop disease or just have mild symptoms. Conclusion　It is necessary to analyze the X chromosome inactivation test for female patients with the pathogenic variation of X-linked recessive genetic disease to determine the possibility of the disease.

Advances in application of induced pluripotent stem cells in childhood genetic diseases / 中国生物制品学杂志

@#Somatic cell reprogramming has developed rapidly in the field of modern biology. Induced pluripotent stem cells(iPSCs)obtained through somatic cell reprogramming are not only capable of self-renewal,but also have multidirectional differentiation potential,which plays an important role in disease modeling and regenerative medicine. This paper reviewed the gene reprogramming technology,the disease models of iPSCs and the application prospects of iPSCs in childhood genetic diseases,so as to provide a reference for the application of iPSCs in the research of mechanism and treatment of various genetic diseases.

Pregnancy management of hepatolenticular degeneration in pregnancy / 中国综合临床

Hepatolenticular degeneration (HLD) is Wilson's disease, which is an autosomal recessive inherited disease caused by gene abnormality and copper transport disorder in liver cells. The pregnancy of HLD patients is safe. During pregnancy, the treatment of eliminating copper should be continued, the dosage of drugs should be reduced according to the condition, and regular monitoring should be done. HLD patients with satisfactory copper control had better pregnancy outcomes than untreated HLD patients. The treatment during pregnancy should be individualized, and perinatal care should be coordinated by obstetrics, hepatology, liver transplantation, genetic counseling, pharmacy, anesthesiology, pediatrics and other disciplines.

Application progress of single cell sequencing technology in diagnosis of genetic and reproductive / 国际生物医学工程杂志

The technique of prenatal diagnosis before embryo implantation has been greatly developed in assisted reproduction, especially for the people with abnormal genetic material to provide the technical possibility of eugenics and eugenics. As an emerging sequencing technology, single-cell sequencing can analyze the genome and transcriptome of cells from the level of a single cell, and reflect the heterogeneity between cells, thus helping to reveal the mechanism of the occurrence and development of diseases. Through prenatal diagnosis before embryo implantation and high-throughput sequencing of single cells obtained from embryo biopsy, euploidy of embryonic chromosomes can be effectively detected, and SNPs and chromosomal copy number variation, insertion, deletion and other variations can also be better detected. It can conduct the comprehensive detection and research of genomic polymorphism and mutation of individual and other species. In this paper, the single-cell sequencing technology and relevant methods was introduced, and the application scenarios of single-cell sequencing in genetic reproduction diagnosis were summarized. The applications of the technology in the field of genetic reproduction were described, and the future directions of the technology were discussed.

Cardiac structural and functional findings in Persian cats with autosomal dominant polycystic kidney disease / Achados estruturais e funcionais cardíacos em gatos persas com doença renal policística autossômica dominante

ABSTRACT: Autosomal dominant polycystic kidney disease (ADPKD) has been related to left ventricular structural and functional abnormalities in human patients. The present study aimed to evaluate the cardiac structural and functional findings in Persian cats with ADPKD. Client-owned ADPKD (n=12) and non-ADPKD (n=12) Persian cats were enrolled in this study. The animals underwent echo- and electrocardiographic (ECG) examinations, and non-invasive measurements of systolic blood pressure (SBP) were obtained. Both groups were similar regarding hematological and biochemical parameters, including white blood cell count and levels of blood urea nitrogen, creatinine, total protein and thyroxine. There were no differences related to ECG parameters between ADPKD and non-ADPKD cats. Left ventricular hypertrophy (LVH) was demonstrated in 6/12 (50%) normotensive ADPKD cats with preserved renal function. There were no differences between animal groups regarding the echocardiographic parameters, including left ventricular ejection fraction and shortening fraction; however, basal interventricular septal thickness at end-diastole near the left ventricular outflow tract and aortic artery flow velocity showed slightly elevated values in ADPKD-cats. Our study revealed that Persian cats with ADPKD do not reproduce the functional and structural cardiac phenotype reported in human patients; however, large-scale cohort studies are necessary to distinguish the possibilities of a true linkage between ventricular myocardial hypertrophy and ADPKD in this breed.

RESUMO: A doença renal policística autossômica dominante (DRPAD) tem sido relacionada a anormalidades estruturais e funcionais de ventrículo esquerdo em pacientes humanos. O objetivo do presente estudo foi avaliar os achados estruturais e funcionais cardíacos em gatos persas com DRPAD. Gatos persas pertencentes à clientes com DRPAD (n=12) e sem DRPAD (n=12) foram envolvidos neste trabalho. Os animais foram submetidos aos exames de eco e eletrocardiografia (ECG) e foram obtidas medições não-invasivas da pressão arterial sistólica (PAS). Ambos os grupos apresentaram valores semelhantes em relação aos parâmetros hematológicos e bioquímicos, incluindo contagem de glóbulos brancos e níveis séricos de ureia, creatinina, proteína total e tiroxina. Não houve diferença em relação aos parâmetros do ECG entre os gatos com ou sem DRPAD. A hipertrofia ventricular esquerda foi demonstrada em 6/12 (50%) dos gatos normotensos com DRPAD e função renal preservada. Não houve diferenças entre os grupos em relação aos parâmetros ecocardiográficos, incluindo fração de ejeção e fração de encurtamento do ventrículo esquerdo, entretanto a espessura septal interventricular basal na diástole na via de saída do ventrículo esquerdo e a velocidade do fluxo da artéria aórtica mostraram valores ligeiramente elevados em gatos com DRPAD. Nosso estudo revelou que gatos persas com DRPAD não reproduzem o fenótipo cardíaco funcional e estrutural encontrado em pacientes humanos. No entanto, estudos de coorte em larga escala são necessários para distinguir as possibilidades de uma verdadeira ligação entre a hipertrofia ventricular do miocárdio e a DRPAD nesta raça.

A case of Noonan syndrome with severe blepharophimosis / 中华整形外科杂志

Noonan syndrome is a genetic multisystem disorder characterised by distinctive facial features, congenital heart disease, short stature, developmental delay, and bleeding diculties. This paper reports a rare Noonan syndrome child who presented chiefly to our institution with severe blepharophimosis. After DAN whole exome sequencing analysis, the patient was diagnosed with the PTPN11 gene c. 1517C> T mutation.

Functional research progress of UBIAD1 and pathogenesis of SCCD / 国际眼科杂志(Guoji Yanke Zazhi)

@#The molecular basis of schnyder crystalline corneal dystrophy(SCCD)is UBIAD1 gene mutation. The pathogenesis of SCCD includes conformational change of UBIAD1 protein which leads to loss of combination with GGpp compounds. UBIAD1-HMG CoA reductase complexes can't be separated, and the rate-limiting enzyme can't dissociate from endoplasmic reticulum to cytoplasm, which results in loss of recognition and degradation by the proteasome. The direct consequence is the gradual accumulation and biosynthesis of cholesterol and non-sterol isoprenoids compounds in the cell. This paper reviews the clinical manifestation, molecular basis, pathogenesis of SCCD and the function of UBIAD1 which provide guidance for molecular diagnosis and treatment of SCCD and pave the way for elucidating the function of UBIAD1 <i>in vivo</i>.

Functional research progress of UBIAD1 and pathogenesis of SCCD / 国际眼科杂志(Guoji Yanke Zazhi)

@#The molecular basis of schnyder crystalline corneal dystrophy(SCCD)is UBIAD1 gene mutation. The pathogenesis of SCCD includes conformational change of UBIAD1 protein which leads to loss of combination with GGpp compounds. UBIAD1-HMG CoA reductase complexes can't be separated, and the rate-limiting enzyme can't dissociate from endoplasmic reticulum to cytoplasm, which results in loss of recognition and degradation by the proteasome. The direct consequence is the gradual accumulation and biosynthesis of cholesterol and non-sterol isoprenoids compounds in the cell. This paper reviews the clinical manifestation, molecular basis, pathogenesis of SCCD and the function of UBIAD1 which provide guidance for molecular diagnosis and treatment of SCCD and pave the way for elucidating the function of UBIAD1 <i>in vivo</i>.

How diseases became "genetic" / Como as doenças se tornaram "genéticas"

Abstract This article examines the origins of the term "genetic disease." In the late 19 and early 20th century, an earlier idea that diseases that occur in families reflect a vague familiar "predisposition" was replaced by the view that such diseases have specific causes, while Mendelian genetics provided then clues to the patterns of their transmission. The genetictisation of inborn pathologies took a decisive turn with the redefinition, in 1959, of Down syndrome as a chromosomal anomaly, then the development of tests for the diagnosis of other hereditary pathologies. At that time, geneticists distinguished "hereditary" diseases that run in families, from "genetic" conditions that are the result of new mutations during the production of egg and sperm cells. In the latter case, the inborn impairment is produced by an anomaly in the genetic material of the cell, but is not hereditary, because it is not transmitted from one or both parents. In the late 20th and early 21st century, new genomic technologies blurred the distinction between hereditary and genetic impairments, extended the concept of genetic disease, and modified the experience of people living with such a disease.

Resumo O presente artigo tem o objetivo de examinar as origens do termo "doença genética. No final do século XIX e início do XX, a vaga ideia que a doença manifesta entre familiares refletia uma "predisposição" familiar, foi substituída pela visão que essas doenças possuem causas específicas, enquanto a genética mendeliana forneceu as pistas para os padrões de transmissão da doença. A genética das patologias congênitas deu uma guinada decisiva, em 1959, com a redefinição da Síndrome de Down como uma anomalia cromossômica e, depois, com o desenvolvimento de testes para o diagnóstico de outras patologias hereditárias. Naquela época, os geneticistas distinguiam doenças "hereditárias" como aquelas que acometiam os elementos de uma família, de condições "genéticas" que são o resultado de novas mutações ocorridas durante a produção dos óvulos e espermatozoides. Neste último caso, a deficiência inata é causada por uma anomalia do material genético da célula, porque não é transmitida por qualquer um ou ambos os pais. No final do século XX e início do XXI, as novas tecnologias genômicas obscureceram a distinção entre deficiências hereditária e a genética, estenderam o conceito da doença genética e modificaram a experiência das pessoas que vivem com esse tipo de doença.

Carrier frequency of autosomal recessive disorders (BC, BLAD, FXID and CVM) in Holstein cows in Jalisco, Mexico

The hereditary autosomal recessive disorders bovine citrullinemia (BC), bovine leukocyte adhesion deficiency (BLAD), factor XI deficiency (FXID), and complex vertebral malformation (CVM) have affected dairy cattle breeding significantly around the world. This study examined the carrier frequency of BC, BLAD, FXID, and CVM autosomal recessive disorders in Bos taurus Holstein cows bred in the Altos Norte region of the state of Jalisco, Mexico. We extracted DNA from 408 random samples of peripheral blood, and then used polymerase chain reaction (PCR) to identify insertion mutations for FXID, and PCR with restriction fragment length polymorphism (PCR-RFLP) for CVM, BC and BLAD. We visualized the PCR products using agarose gel electrophoresis stained with GelRed®. We found that 100% of wild-type (N/N) allele homozygous animals for genes CD18, ASS, and FXI were free of the mutations for BLAD, BC and FXID respectively. For gene SLC35A3 we estimated total carrier frequency of 10.3% and allele frequency of 5%.(AU)

General anesthesia for an adolescent with Pelizaeus-Merzbacher disease: A case report

Pelizaeus-Merzbacher disease (PMD) is a progressive and degenerative chromosomal disorder of the central nervous system caused by defective myelin production. Few case reports have been issued on the anesthetic management of PMD, because of its extremely low incidence. We anesthetized a 13-year-old female patient diagnosed with PMD for ophthalmic surgery because of intermittent exotropia. General anesthesia was induced and maintained with propofol and sevoflurane in air and oxygen. Rocuronium was administered to facilitate orotracheal intubation, and residual neuromuscular blockage was reversed with pyridostigmine. Between emergence to 24 hours postoperatively, her muscle power completely recovered and no unpredictable events occurred. Summarizing, anesthesiologists should be concerned about the high possibility of aspiration, spasticity, and seizure during the perioperative period in patients with even mild PMD. Appropriate preoperative evaluation, intraoperative monitoring, and choice of proper anesthetic drugs enable safe anesthesia in patients with PMD.

Frequency of canine degenerative myelopathy SOD1:c.118G>A mutation in 22 dog breeds in Guadalajara, Mexico / Frecuencia de la mutación SOD1:c.118G>A de mielopatía degenerativa canina en 22 razas de perros en Guadalajara, México / Frequência da mutação SOD1: c.118G>A de mielopatía degenerativa canina em 22 raças de cães no Guadalajara, México

Abstract Background: Canine degenerative myelopathy (DM) is a late-onset disease that primarily affects large-breed dogs. The disease involves the spinal cord and produces progressive paresia and, eventually, complete loss of mobility. DM has been related to missense mutation c.118G>A in the SOD1 gene. Objective: To determine the genotypic and genic frequencies of DM in Mexico. Methods: In total, 330 samples from 22 different dog breeds were genotyped using the polymerase chain reaction and restriction fragment length polymorphisms (PCR-RFLP) technique. Results: The mutation was identified in 71 animals from 11 different breeds. Observed genic frequencies were 0.78 for the G allele and 0.14 for the A allele. Genotypic frequencies were 0.79 for the G/G wild-type, 0.14 for the G/A heterozygote, and 0.7 for the A/A homozygote. Conclusion: The genic frequency of this allele is high among the studied populations. A molecular marker program that identifies the DM mutation in breeding dogs should be implemented in order to reduce this frequency.

Resumen Antecedentes: La mielopatía degenerativa canina (MD) es una enfermedad progresiva de presentación tardía que afecta a la médula espinal, generalmente en caninos de razas grandes, y que produce paresis progresiva y eventual pérdida completa de la movilidad. Se ha relacionado con una mutación puntual por sustitución de bases en el gen SOD1 recientemente identificado como c.118G>A. Objetivo: Determinar las frecuencias genotípicas y génicas para la presentación de DM en México. Métodos: Se genotipificaron 330 muestras de perros de 22 razas mediante la técnica de reacción en cadena de la polimerasa y polimorfismos de longitud de fragmentos de restricción (PCR- RFLPs). Resultados: Se identificó la mutación en 71 animales de 11 razas diferentes. Las frecuencias génicas encontradas fueron de 0,78 para el alelo G y de 0,14 para el alelo A. Las frecuencias genotípicas fueron de 0,79 para el tipo silvestre G/G, 0,14 para el heterocigoto G/A y 0,7 para el homocigoto A/A. Conclusión: La frecuencia encontrada para la mutación es alta en las poblaciones estudiadas. La aplicación de un programa de selección asistida por marcadores moleculares contra la mutación causante de MDC en perros reproductores resultaría útil para reducir su frecuencia.

Resumo Antecedentes: A mielopatía degenerativa canina (MD) é uma doença progressiva de apresentação tardia que afeta a medula espinal geralmente de caninos de raças grandes e que produz paresia progressiva e eventualmente a perda completa da mobilidade. Tem sido relacionada com uma mutação pontual por substituição de bases no gen SOD1, recentemente identificado como c.118G>A. Objetivo: Determinar as frequências genotípicas e genéticas para a apresentação de DM no México. Métodos: Genotipagem de 330 amostras de cães de 22 raças por meio da técnica de reação em cadeia da polimerase e polimorfismos no comprimento de fragmentos de restrição (PCR- RFLPs). Resultados: A mutação foi identificada em 71 animais de 11 raças diferentes. As frequências gênicas encontradas foram de 0,78 para o alelo G e de 0,14 para o alelo A. As frequências genotípicas foram de 0,79 para o tipo silvestre G/G, 0,14 para o heterozigoto G/A e 0,7 para o homozigoto A/A. Conclusão: A frequência encontrada para a mutação é alta nas populações estudadas. A implementação de um programa de seleção assistida por marcadores moleculares contra a mutação que causa MDC seria útil para reduzir a sua frequência.