Fabry disease: molecular studies in Italian patients and X inactivation analysis in manifesting carriers

Abstract

Anderson-Fabry disease (E C 3.2.1.22, MIM 301500) is an X linked lysosomal storage disorder caused by a deficiency of the enzyme α-galactosidase A (GLA).1,2 The onset of the disease and the severity of clinical manifestations depend principally on residual GLA enzymatic activity.1 Fabry disease can be classified into two clinical phenotypes: the classical form and the cardiac variant.1,3 The classical form is mainly characterised, in affected hemizygous males, by angiokeratoma, acroparaesthesias, hypohidrosis, pains, fever crises, and involvement of the kidneys, brain, and heart. Neurological and/or psychological manifestations with personality disturbances can also occur.1 The cardiac variant is characterised by symptoms restricted to cardiac abnormalities, including conduction defects and/or late onset cardiomyopathy with left ventricular hypertrophy.1,3,4 A prevalence of Fabry disease in a referral population of male patients with a clinical diagnosis of late onset hypertrophic cardiomyopathy (HCM) has also been reported.5 The X linked disorders affect males, while the female carriers are generally asymptomatic, owing in part to the random inactivation of the X chromosome.6 Fabry female carriers can be asymptomatic or clinically affected, usually with a late onset and mild form of the disease. Corneal abnormalities are the most frequent clinical manifestations.1 The human GLA gene, mapped on Xq22, is organised in seven exons encompassing over 12 kb.7 So far, about 265 mutations spread throughout the GLA gene in all exons have been reported in the Human Gene Mutation Database Web site and, in addition, a further 65 have been published.8,9 ### Key points