[Contribution of the measurement of globotriaosylceramide in urine to the diagnosis and follow-up of Fabry disease].

Globotriaosylceramide (Gb(3)) has been measured in urine of 35 male hemizygotes and 66 female heterozygotes for Fabry disease (FD). In males, Gb(3) measurement allows to confirm the diagnosis which is based on deficient α-galactosidase A (α-Gal A) activity in leukocytes. Our results show that hemizygotes for classic FD have increased Gb(3) and C24/C18 isoforms ratio. Hemizygotes for FD variants have slightly elevated or normal Gb(3) and/or C24/C18 ratio. These variants often have a residual α-Gal A activity, and milder clinical signs. In females, urinary Gb(3) is more informative than α-Gal A activity in leukocytes. Our study shows that urinary Gb(3) (measurement and C24/C18 ratio) allows the diagnosis of 92 % of classical FD heterozygotes, and is often normal in variant FD heterozygotes. The diagnosis of FD heterozygote cannot be completely excluded even if urinary Gb(3) and α-Gal A in leukocytes are normal. Urinary Gb(3) can be used for therapeutic follow-up (enzyme replacement therapy) when increased.