RESUMEN
BACKGROUND & OBJECTIVES: Genetic diagnosis of spinal muscular atrophy (SMA) is complicated by the presence of SMN2 gene as majority of SMA patients show absence or deletion of SMN1 gene. PCR may amplify both the genes non selectively in presence of high amount of DNA. We evaluated whether allele-specific PCR for diagnostic screening of SMA is reliable in the presence of high amount of genomic DNA, which is commonly used when performing diagnostic screening using restriction enzymes. METHODS: A total of 126 blood DNA samples were tested in amounts ranging 80-200 ng, referred for the genetic diagnosis of SMA using both conventional PCR-RFLP and allele-specific PCR. RESULTS: The results from both methods showed agreement. Further, allele-specific PCR was found to be a time-efficient and cost-effective method. INTERPRETATION & CONCLUSIONS: Our study demonstrated the accuracy of our allele-specific PCR and the results were comparable compatible with that of PCR-RFLP, indicating its practical application in SMA diagnostic screening.
Asunto(s)
Atrofia Muscular Espinal/diagnóstico , Reacción en Cadena de la Polimerasa/métodos , Proteína 1 para la Supervivencia de la Neurona Motora/sangre , Adolescente , Alelos , Niño , Exones , Femenino , Costos de la Atención en Salud , Humanos , Masculino , Atrofia Muscular Espinal/patología , Eliminación de Secuencia , Proteína 1 para la Supervivencia de la Neurona Motora/genética , Proteína 2 para la Supervivencia de la Neurona Motora/sangre , Proteína 2 para la Supervivencia de la Neurona Motora/genéticaRESUMEN
Duchenne Muscular Dystrophy (DMD) is an X-linked recessive genetic disorder characterized by rapidly progressive muscle weakness. The disease is caused by deletion, duplication or point mutation of the dystrophin gene, located on the X chromosome (Xp21). Deletion accounts for 60% of the mutations within the 79 exons of the dystrophin gene. Seven exons (43, 44, 45, 46, 49, 50, and 51) were found to be most commonly deleted among the Asian patients. To detect the frequency of deletion of these 7 exons in Malaysian DMD patients, we carried out a molecular genetic analysis in 20 Malaysian DMD patients. The mean age of initial presentation was 60 months (SD 32 months, range 5-120 months). Fourteen patients were found to have deletion of at least one of the seven exons. The remaining six patients did not show any deletion on the tested exons. Deletions of exons 49, 50 and 51 were the most frequent (71.43%) and appear to be the hot spots in our cohort of patients.
Asunto(s)
Deleción Cromosómica , Distrofina/genética , Distrofia Muscular de Duchenne/genética , Adolescente , Niño , Preescolar , Exones , Humanos , Lactante , Malasia , MasculinoRESUMEN
In Malaysia, Spinal Muscular Atrophy (SMA) is diagnosed based on clinical observation with or without muscle biopsy. Molecular analyses of the SMA-related genes have not been available so far. In this preliminary study, we searched for homozygous deletion of Survival Motor Neuron (SMN1) and Neuronal Apoptosis Inhibitory Protein (NAIP) genes in Malay patients with SMA and found homozygous deletion of SMN1 exon 7 and 8 in all the patients while homozygous deletion of NAIP exon 5 was detected in only our type 1 patients but not in the type 3 patient. To the best of our knowledge, these are the first SMA cases diagnosed at the molecular level in Malaysia.