부산대학교 도서관

Introduction: 5-10% of patients with amyotrophic lateral sclerosis, ALS, have a family history of disease, and of these cases around 20% harbour mutations in the Cu/Zn superoxide dismutase gene, SOD1. Unique among the over 100 SOD1 mutations identified is the D90A mutation, which is dominant in most populations, but recessive in some parts of Scandinavia, where 2-5% of the normal population are heterozygous carriers. Clinical details: We outline the clinical features and neurophysiological investigations of two dizygotic English twin brothers with ALS. The first presented aged 46 years and his disease rapidly progressed leading to his death aged 50. His brother developed hand weakness aged 52 years. This has gradually progressed to include lower limb weakness, but his bulbar and respiratory function remain good some 4 years after symptom onset. There is no other history of ALS in this family, and the parents were not consanguineous. Genetic Analysis: This showed a heterozygous D90A SOD1 mutation in samples from the live brother, and no other mutations. Screening of archived DNA from the deceased brother revealed normal SOD1 sequence. DNA fingerprinting analysis confirmed that no sample mix-ups had occurred. Discussion: One explanation of these results is that the heterozygous D90A mutation is of no relevance to the ALS phenotype in the live brother. Both brothers may harbour an identical mutation in another, as yet unidentified, gene. The disease course is less severe in the brother with the D90A mutation, in keeping with theories of D90A being linked to a protective factor. Other explanations include possible mosaicism or of genetic translocations in the SOD1 region. We are currently obtaining DNA samples from furthe family members for haplotyping around SOD1 and other loci. [ABSTRACT FROM AUTHOR]