RESUMO
Introducción. Las atrofias musculares espinales de la infancia son enfermedades neuromusculares hereditarias, autosómicas, recesivas, caracterizadas por la degeneración de las neuronas motoras del asta anterior de la médula espinal. La atrofia muscular espinal tipo I (enfermedad de Werdnig-Hoffmann) es la forma más severa. Se inicia in útero o durante los primeros meses de vida. La muerte suele ocurrir antes de los dos años de edad. Caso clínico. Lactante de 6 meses de edad que ingresa al Servicio de Urgencias por dificultad respiratoria severa. Presenta marcada hipotonía muscular, debilidad de musculatura intercostal y fasciculaciones de la lengua. La electromiografía es compatible con polineuropatía motora con daño mielínico y axonal. El análisis molecular reportó un estado homocigoto para la deleción de los exones 7 y 8 del gen SMN-1 . Con estos dos estudios se integra el diagnóstico de atrofia muscular espinal tipo 1 (enfermedad de Werdnig-Hoffmann). Conclusiones. Es importante conocer y diagnosticar esta entidad para brindar consejo genético a la familia, así como asesoramiento y apoyo en el manejo del paciente.
Background. Childhood spinal muscular atrophy is an autosomal recessive neuromuscular disease characterized by degeneration of the anterior horn cells of the spinal cord. SMA type I, the most severe form (Werdnig-Hoffmann disease) can be detected in utero or during the first months of life. Death typically occurs within the first 2 years of life. Case report. A 6-month-old female was admitted to the emergency room for severe respiratory distress. She had muscular hypotonia, intercostal muscle weakness and tongue fasciculations. Electromyography was compatible with motor polyneuropathy with axonal and myelin damage. Molecular analysis of SMN-1 gene reported homozygous for deletion of exons 7 and 8 of SMN-1 gene. Conclusions. It is imperative to recognize and diagnose this entity in order to provide genetic counseling to the family as well as to offer support and advice in the care of the patient.
RESUMO
PURPOSE: To describe the molecular defects in the Norrie disease protein (NDP) gene in two families with Norrie disease (ND). METHODS: We analysed two families with ND at molecular level through polymerase chain reaction, DNA sequence analysis and GeneScan. RESULTS: Two molecular defects found in the NDP gene were: a missense mutation (265C > G) within codon 97 that resulted in the interchange of arginine by proline, and a partial deletion in the untranslated 3' region of exon 3 of the NDP gene. Clinical findings were more severe in the family that presented the partial deletion. We also diagnosed the carrier status of one daughter through GeneScan; this method proved to be a useful tool for establishing female carriers of ND. CONCLUSION: Here we report two novel mutations in the NDP gene in Mexican patients and propose that GeneScan is a viable mean of establishing ND carrier status.
