[The spectrum of spinal muscular atrophies: a population study].
: A population medical genetic study of spinal muscular atrophies (SMA) was carried out in 1800 individuals in 6 russian and 3 middle asian regions. 33 patients with SMA were ascertained including 29 with autosomal recessive childhood proximal SMA (SMA I-III) and 4 patients with rare SMA types. There were revealed either overlapping of diagnostic criteria of I-III types in some patients or interfamilial differences of types in 3 from 6 familial cases, (one of them with distant relatives affected as well as pronounced clinical genetic variability of rare forms of SMA (all sporadic cases).