Medknow Publications on behalf of Indian Society of Human Genetics
Abstract
Huntington′s disease (HD) is an inherited neurodegenerative
disorder characterized by chorea and progressive dementia. The mutation
causing the disease has been identified as an unstable expansion of a
trinucleotide (CAG) n at the 5′ end of the IT 15 gene on
chromosome 4. We have analyzed the distribution of CAG repeats in 71
Iranian individuals (34 patients and 37 unaffected family members)
belonging to 31 unrelated families thought to segregate HD. We found
one expanded CAG allele in 22 individuals (65%) belonging to 21
unrelated families. In these HD patients, expanded alleles varied from
40 to 83 CAG units and normal alleles varied from 13 to 36 CAGs. A
significant negative correlation between age at onset of symptoms and
size of the expanded CAG allele was found (r= - 0.51; P=0. 1). In
addition, we genotyped 25 unrelated control individuals (total of 50
alleles) and found normal CAG repeats varying from 10 to 34 units. In
conclusion, our results showed that molecular confirmation of the
clinical diagnosis in HD should be sought in all suspected patients,
making it possible for adequate genetic counseling. This Study is the
first report of molecular diagnosis of Huntington disease among Iranian
population and ever in Middle East and with regard to high frequency of
consanguinity marriage in this region