Fabry disease: six gene rearrangements and an exonic point mutation in the alpha-galactosidase gene.

Abstract

Fabry disease, an X-linked recessive disorder of glycosphingolipid catabolism, results from the deficient activity of the lysosomal hydrolase, a-galactosidase. Southern hybridization analysis of the a-galactosidase gene in affected hemizygous males from 130 unrelated families with Fabry disease revealed six with different gene rearrangements and one with an exonic point mutation resulting in the obliteration of an Msp I restriction site. Five partial gene deletions were detected ranging in size from 0.4 to > 5.5 kb. Four of these deletions had breakpoints in intron 2, a region in the gene containing multiple Alu repeat sequences. A sixth genomic rearrangement was identified in which a region of about 8 kb, containing exons 2 through 6, was duplicated by a homologous, but unequal crossover event. The Msp I site obliteration, which mapped to exon 7, was detected in an affected hemizygote who had residual enzyme activity. Genomic amplification by the polymerase chain reaction and sequencing revealed that the obliteration resulted from a C to T transition at nucleotide 1066 in the coding sequence. This point mutation, the first identified in Fabry disease, resulted in an arginine356 to tryptophan3% substitution which altered the enzyme's kinetic and stability properties. The detection of these abnormalities provided for the precise identification of Fabry heterozygotes, thereby permitting molecular pedigree analysis in these families which revealed paternity exclusions and the first documented new mutations in this disease.

A 3′ splice site consensus sequence mutation in the intron 3 of the α-galactosidase a gene in a patient with Fabry disease

“…Bernstein et al (1989) reported that partial gene deletions were seen only seven families out of 130 families by Southern blotting analysis. They also reported a point mutation (C---,T) detected by MspI digestion of the genomic DNA PCR product.…”

“…Since then molecular analysis of this disease has been reported. Various types of deletion of genomic DNA were found in about 5~ of patients (Bernstein et aL, 1989) and point mutations have been reported from the rest of patients (Bernstein et al, 1989;Koide et al, 1990;Sakuraba et al, 1990).…”

Schindler disease: the molecular lesion in the alpha-N-acetylgalactosaminidase gene that causes an infantile neuroaxonal dystrophy.

“…The COS-1 cell lines were obtained from the American Type Culture Collection (Rockville, MD). The fibroblasts, lymphoblasts, and COS-1 cell lines were grown in RPMI 1640 media supplemented with 10% fetal bovine serum, 1% penicillin, and I mg/ml streptomycin by standard procedures (10).…”

A mutation in the 5′ untranslated region of the human α‐galactosidase A gene in high‐activity variants inhibits specific protein binding

“…A severe deficiency in ~-Gal A activity results in Fabry disease, a glycosphingolipid storage disorder. Many different mutations in the et-GAL A gene have been correlated with this disease, including partial gene deletions, insertions, and a variety of single-base substitutions affecting mRNA processing or translation [7,8].…”