THE GENE ENCODING P44, A SUBUNIT OF THE TRANSCRIPTION FACTOR TFIIH, IS INVOLVED IN LARGE-SCALE DELETIONS ASSOCIATED WITH WERDNIG-HOFFMANN DISEASE

Mutations of the survival motor neurone gene (SMN) are associated with spinal muscular atrophy (SMA), a frequent lethal autosomal recessive disorder, In spite of this, no phenotype-genotype correlation was obse rved, since the SMN gene is lacking in the majority of patients affect ed with either the severe form (type I) or the milder forms (types II and III). Here, we show that the gene encoding p44, a subunit of the b asal transcription factor TFIIH, is duplicated in the SMA region and t hat the p44 gene products (p44t and p44c) differ by three amino acid c hanges, Gene analysis of a total of 94 unrelated SMA patients revealed that the p44t gene is involved in large-scale deletions associated wi th Werdnig-Hoffmann disease (type I), The TFIIH polypeptide compositio n as well as transcription and DNA repair activities are normal in pat ients lacking the p44t gene on both. mutant chromosomes, suggesting th at the p44t gene is not critical for the development of SMA.