Fabry disease: Identification of 50 novel α-galactosidase A mutations causing the classic phenotype and three-dimensional structural analysis of 29 missense mutations

Abstract

Fabry disease, an X-linked recessive inborn error of glycosphingolipid catabolism, results from the deficient activity of the lysosomal exoglycohydrolase, α-galactosidase A (EC 3.2.1.22; α-Gal A). The molecular lesions in the α-Gal A gene causing the classic phenotype of Fabry disease in 66 unrelated families were determined. In 49 families, 50 new mutations were identified, including: 29 missense mutations (N34K, T41I, D93V, R112S, L166G, G171D, M187T, S201Y, S201F, D234E, W236R, D264Y, M267R, V269M, G271S, G271V, S276G, Q283P, A285P, A285D, M290I, P293T, Q312H, Q321R, G328V, E338K, A348P, E358A, Q386P); nine nonsense mutations (C56X, E79X, K127X, Y151X, Y173X, L177X, W262X, Q306X, E338X); five splicing defects (IVS4-1G > A, IVS5-2A > G, IVS5 + 3A > G, IVS5 + 4A > G, IVS6-1G > C); four small deletions (18delA, 457delGAC, 567delG, 1096delACCAT); one small insertion (996insC); one 3.1 kilobase Alu-Alu deletion (which included exon 2); and one complex mutation (K374R, 1124delGAG). In 18 families, 17 previously reported mutations were identified, with R112C occurring in two families. In two classically affected families, affected males were identified with two mutations: one with two novel mutations, D264Y and V269M and the other with one novel (Q312H) and one previously reported (A143T) mutation. Transient expression of the individual mutations revealed that D264Y and Q312H were localised in the endoplasmic reticulum and had no detectable or markedly reduced activity, whereas V269M and A143T were localised in lysosomes and had approximately 10 per cent and approximately 35 per cent of expressed wild-type activity, respectively. Structural analyses based on the enzyme's three-dimensional structure predicted the effect of the 29 novel missense mutations on the mutant glycoprotein's structure. Of note, three novel mutations (approximately 10 per cent) were predicted not to significantly alter the glycoprotein's structure; however, they were disease causing. These studies further define the molecular heterogeneity of the α-Gal A mutations in classical Fabry disease, permit precise heterozygote detection and prenatal diagnosis, and provide insights into the structural alterations of the mutant enzymes that cause the classic phenotype.

Repetitive sequence environment distinguishes housekeeping genes

“…Indeed, there are numerous reports of disease-causing deletions resulting from recombination between Alu elements (Batzer and Deininger, 2002;Nishimura et al, 2005;Casarin et al, 2006;Has et al, 2006;Kozak et al, 2006;Li et al, 2006;Matejas et al, 2006;Nissen et al, 2006;Sen et al, 2006;Shabbeer et al, 2006;Uddin et al, 2006;Xie et al, 2006;Zhang et al, 2006). If a large proportion of Alu elements indeed fosters euchromatic domains as suggested by the aforementioned study (Willoughby et al, 2000), then flanking sequences may also be destabilized.…”

Clinical Pregenetic Screening for Stroke Monogenic Diseases

“…Table 2 summarizes the detailed results of genetic analysis. [16][17][18][19][20][21][22][23] Clinical and demographic characteristics were compared between individuals positive and negative on genetic testing ( Table 3). The only significant difference was a family history of stroke (92% versus 47%; P=0.002).…”

Newborn Screening for Lysosomal Storage Disorders in Hungary

“…As already mentioned, screening for Fabry disease yielded three females affected by a known causative mutation c.427 G>A (p.A143T) (Eng et al 1997), though it is known to be associated with both the classic (Blaydon et al 2001) and variant phenotype (Shabbeer et al 2006) of Fabry disease. Since females are affected in a very heterogeneous manner, the biological significance of the mutation remains to be identified.…”