<unk>  is inherited in an<unk><unk>  recessive pattern. The gene associated with this disorder, UBA1, is located on the<unk>  chromosome at<unk> p11.3 and contains 27 exons; moreover, translation begins at the second exon. In males, if the<unk>  chromosome contains an altered copy of the gene then the male will have the disorder. In females, a mutation of the gene on both<unk>  chromosomes would have to occur in order for the female to have the disorder. Since females are unlikely to have two altered copies of the gene, males are affected by this disorder much more frequently than females. A recent study has resulted the in detection of three rare novel variants in exon 15 of UBA1 that segregated with the disease: two missense mutations present in each of one<unk> LSMA family (314370.0001, 314370.0002), and one synonymous C-to-T substitution (314370.0003) identified in another three unrelated families. Moreover, in a sixth family, neither of the two missense mutations or the synonymous substitution was identified. Ramser et al. (2008) demonstrated that the synonymous C-to-T substitution leads to significant reduction of UBA1 expression and alters the methylation pattern of exon 15, implying a plausible role of this DNA element in developmental UBA1 expression in humans. Thus, SMAX2 is one of several neurodegenerative disorders associated with defects in the ubiquitin-proteasome pathway. The severity of SMAX2 does not waiver regardless of the type of causative mutation.
X-linked spinal muscular atrophy type 2
Jokela type spinal muscular atrophy
Fukuyama congenital muscular dystrophy
Distal spinal muscular atrophy type 2
Ullrich congenital muscular dystrophy
Distal spinal muscular atrophy type 1
Madras motor neuron disease
Becker muscular dystrophy