American Journal of Medical Genetics 136A:58–62 (2005) Application of a Comprehensive Protocol for the Identification of Gaucher Disease in Brazil Kristiane Michelin, 1,2 Alessandro Wajner, 1,2 Fernanda T.S. de Souza, 1,2 Alexandre S. de Mello, 1 Maira G. Burin, 1 Maria Luiza S. Pereira, 1,2 Ricardo F. Pires, 1 Roberto Giugliani, 1,3 and Janice C. Coelho 1,2 * 1 Medical Genetics Service, Hospital de Clı´nicas de Porto Alegre, Porto Alegre, Rio Grande do Sul, Brazil 2 Biochemistry Department, ICBS, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil 3 Genetics Department, IB, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil Gaucher disease (GD) is a sphingolipidosis caused by a genetic defect that leads to glucocerebrosi- dase (b-glucosidase) deficiency. Between January 1982 and October 2003, 1,081 blood samples from patients suspected of having GD were referred for biochemical analysis. The activities of the enzymes b-glucosidase (b-glu) and chitotriosidase (CT) were measured in these samples. Among the 412 diagnosed cases of GD (38.1%), the great majority were GD type 1. The Brazilian regions with the greatest concentration of these patients were the Southeast, South, and Northeast. The mean age of patients at diagnosis was 19 years. The activity of b-glu in patients with GD was, on average, 10.7% of that of normal individuals. CT was, on average, 269 times more elevated in this group of patients. Among the 669 cases with no confirmation of GD, there were patients with Niemann–Pick disease types A, B, or C (44 cases), possible heterozygotes for GD (59 cases), patients with other lysosomal storage diseases (LSDs) (19 cases) or with other inborn errors of metabo- lism (3 cases). In 508 cases, no metabolic disorder was found. This study shows that the biochemical protocol employed was effective for the detection of GD, a disease that is reasonably frequent in Brazil. ß 2005 Wiley-Liss, Inc. KEY WORDS: lysosomal storage disorders; b- glucosidase; chitotriosidase; Gau- cher disease; sphingolipidoses INTRODUCTION Gaucher disease (GD) is an inborn error of metabolism (IEM) with an autosomal recessive inheritance pattern. It consists of a sphingolipidosis characterized by the storage of glucosylcer- amide in reticuloendothelial system cells. This storage is due to the deficiency of b-glucosidase (b-glu) or glucocerebrosidase (EC 3.2.1.45) [Brady et al., 1965; Barranger and Ginns, 1989]. In rare cases, GD occurs due to the deficiency of a b-glucosidase activator due to a defect in its enconding gene [Beutler and Grabowski, 2001]. There are three clinical subtypes in GD: GD type 1 (chronic non-neuronopathic variant), GD type 2 (acute neuronopathic variant), and GD type 3 (subacute neuronopathic variant) [Beutler and Grabowski, 2001]. GD type 1 is the most frequent variant, particularly in certain ethnic groups, such as Ashkenazi Jews (1:1,000) [Kolodny et al., 1982]. Usually, it is considered a pan-ethnic disease with a frequency of 1:50,000 to 1:100,000 [Meikle et al., 1999]. GD type 1 is characterized by damage to end organ, such as spleen, liver, bones, and lungs, and a variable clinical expression. The existence of distinct mutations in the b-glu gene can partially explain the heterogeneity in the presentation of GD type 1 [Tsujii et al., 1988; Barranger and Ginns, 1989; Theophilus et al., 1989]. Approximately 200 mutations in the b-glu gene are asso- ciated with GD. Moreover, the genotype–phenotype correla- tion is not always well defined. In some cases, involving rare alleles this association is more difficult due to the fact that there are only a few affected patients available for study. However, it is already well established that the N370S mutation in the two alleles is associated with GD type 1. This mutation, when present in one of the alleles of an affected patient is also associated with GD type 1 [Beutler et al., 1993]. In contrast, genotype L444P/L444P is strictly associated with the neuronopathic phenotype (GD type 2), the most serious form of the disease [Erikson, 1986]. The laboratory diagnosis of GD is based on the measurement of b-glu activity [Beutler and Grabowski, 2001] and is assisted by a biochemical marker: the measurement of the enzyme chitotriosidase (CT). The latter is a synthesized enzyme excreted by activated macrophages [Hollak et al., 1994]. In the 90th decade, some investigations showed that GD patients had elevated levels of plasma CT (approximately 100–500 times) and that these levels lowered considerably after the intro- duction of enzyme replacement therapy [Guo et al., 1995; Czartoryska et al., 2000; Elstein et al., 2000; Korolenko et al., 2000]. CT, whose physiologic role is not yet well elucidated is present in the liver, kidneys, spleen, lungs, and bone marrow [Guo et al., 1995]. It is established that 6% of the population carries some degree of deficiency for this enzyme, what does not lead to any symptoms [Andersen et al., 1997]. The present study aimed at diagnosing GD through the application of a biochemical protocol in a sample of 1,081 high risk individuals from various Brazilian states and characteriz- ing these individuals on a demographic and biochemical basis. MATERIALS AND METHODS Sample From January 1982 until October 2003, the reference laboratory for inborn errors of metabolism of the Medical Genetics Service of Hospital de Clı ´nicas de Porto Alegre, South of Brazil, received blood samples from 1,081 individuals with suspected GD. These samples came from various areas of *Correspondence to: Janice C. Coelho, Ph.D., Medical Genetics Service, Hospital de Clı ´nicas de Porto Alegre, Rua Ramiro Barcelos, 2350, Porto Alegre, RS, Brazil 90035-003. E-mail: jcoelho@hcpa.ufrgs.br Received 8 September 2004; Accepted 7 April 2005 DOI 10.1002/ajmg.a.30787 ß 2005 Wiley-Liss, Inc.