BACKGROUND: Family genetic testing of patients newly diagnosed with a rare genetic disease can improve early diagnosis of family members, allowing patients to receive disease-specific therapies when available. Fabry disease, an X-linked lysosomal storage disorder caused by pathogenic variants in GLA, can lead to end-stage renal disease, cardiac arrhythmias, and stroke. Diagnostic delays are common due to the rarity of the disease and non-specificity of early symptoms. Newborn screening and screening of at-risk populations, (e.g., patients with hypertrophic cardiomyopathy or undiagnosed nephropathies) can identify individuals with Fabry disease. Subsequent cascade genotyping of family members may disclose a greater number of affected individuals, often at younger age than they would have been diagnosed otherwise. METHODS: We conducted a literature search to identify all published data on family genetic testing for Fabry disease, and discussed these data, experts' own experiences with family genetic testing, and the barriers to this type of screening that are present in their respective countries. RESULTS: There are potential barriers that make implementation of family genetic testing challenging in some countries. These include associated costs and low awareness of its importance, and cultural and societal issues. Regionally, there are barriers associated with population educational levels, national geography and infrastructures, and a lack of medical geneticists. CONCLUSION: In this review, the worldwide experience of an international group of experts of Fabry disease highlights the issues faced in the family genetic testing of patients affected with rare genetic diseases.

• Klíčová slova
• Fabry disease, at-risk populations screening, cascade genotyping, early diagnosis, family genetic testing, pedigree drawing, rare disease,
• MeSH
• Fabryho nemoc diagnóza   genetika   MeSH
• genetické testování metody   normy   MeSH
• lidé MeSH
• rodokmen MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH

We have identified 21 different alpha-galactosidase A gene (GLA) mutations in 22 unrelated Czech and Slovak families with Fabry disease. Eleven of these mutations were novel (point mutations D93N, A135V, D155H, G171R, Q280K, G360S, Q330X, splicing errors c.194ins14, c.801ins36 and deletions c.674_732del59, g.3405_6021del2617). Genotyping of family members for family-specific mutations revealed 55 heterozygotes that manifested clinical symptoms of different severity. To examine the contribution of X-inactivation skewing to disease manifestation in Fabry heterozygotes, we have adopted the Mainz severity scoring scheme and compared the score values with the X-inactivation status in 39 carriers in an age-dependent manner. The age-score trendline of Fabry females who had a predominantly inactivated X-chromosome bearing a wild-type GLA allele (10 of 38 females) was markedly steeper than in the rest of the cohort. One female carrier with an inactivated mutated allele had a low score value when compared to the other heterozygotes of the same age. These data suggest that X-inactivation is indeed a major factor determining the severity of clinical involvement in Fabry heterozygotes. There was a statistically significant difference between the severity score values of heterozygotes with random and non-random X-chromosome inactivation at the 5% level of significance. Further studies will show if the degree of the wildtype allele inactivation will be useful as a predictive marker of severity of phenotype in Fabry heterozygotes. Although the correlation between X-inactivation skewing and presentation of the disease in Fabry heterozygotes has previously been suggested in the literature, this report is among the first attempts to examine this relationship systematically.

• MeSH
• alfa-galaktosidasa genetika   MeSH
• bodová mutace MeSH
• dítě MeSH
• dospělí MeSH
• Fabryho nemoc epidemiologie   genetika   MeSH
• genetické nemoci vázané na chromozom X * MeSH
• heterozygot MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• stupeň závažnosti nemoci MeSH
• umlčování genů * MeSH
• věkové faktory MeSH
• Check Tag
• dítě MeSH
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Česká republika epidemiologie   MeSH
• Slovenská republika epidemiologie   MeSH
• Názvy látek
• alfa-galaktosidasa MeSH