1. ¹Instituto de Genética Médica Jacinto de Magalhães, Porto, Portugal
2. ²Instituto de Biologia Molecular & Celular (IBMC), Portugal

Correspondence: Dr MC Sá Miranda, IBMC, Rua do Campo Alegre 823, 4150-180 Porto, Portugal. Tel.: 351 22 607 4970; Fax: 351 22 609 2404; E-mail: mcsamir@ibmc.up.pt

Received 16 August 2002; Revised 28 April 2003; Accepted 13 May 2003; Published online 17 December 2003.

Abstract

Lysosomal storage diseases (LSDs) are a group of inherited metabolic disorders individually considered as rare, and few data on its prevalence has been reported in the literature. The overall birth prevalence of the 29 different LSDs studied in the Portuguese population was calculated to be 25/100 000 live births, twice the prevalence previously described in Australia and in The Netherlands. The comparison of the prevalence profile of the LSDs presenting a prevalence higher than 0.5/100 000 in the Portuguese, Dutch and Australian populations showed, in the Portuguese, the existence of a higher prevalence of GM2 gangliosidoses (B variant), mucolipidoses (II and III), Niemman-Pick type C and metachromatic leukodystrophy (MLD), and a lower prevalence of Pompe and Fabry. The highest prevalence value for a single LSD is the one of GM2 gangliosidoses (B variant), corresponding to 3/100 000, a value which is significantly higher than the prevalence of the most frequent LSD in Dutch, Pompe disease (2/100 000) and Australians, Gaucher's disease (GD) (1.8/100 000). It is worth noting that the highest prevalence of GM2 gangliosidoses found in the Portuguese is mainly due to the existence of a unique subtype, the rare juvenile B1 variant.