Rastreamento de mutações nos genes PITX2, FOXC1 e GJA1 em pacientes com sindrome de Axenfeld-Rieger associada a glaucoma

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

Axenfeld-Rieger Syndrome (ARS) is arare disorder, usually transmitted in an autosomal dominant pattem characterized by anterior segment dysgenesis and often associated with developmental glaucoma. In addition to the ocular changes observed in ARS, syndromic features can also occur, such as facial bone defects, teeth anomalies and peri-umbilical skin involution. Two transcription factor genes, PITX2 on chromosome 4q25 and FOXCl on chromosome 6p25, have been associated with the ARS phenotype through mutational events. Recently, the GJAl gene (connexin 43), associated with oculodentodigital dysplasia (ODDD) syndrome, which presents some similarities with ARS, was identified. The ODDD syndrome is characterized by malformations that involve the face, eyes, teeth and bones. The ocular abnormalities include microphthalmos and anterior segment dysgenesis that may lead to glaucoma as well. The main purpose of this study was to evaluate FOXCl, PITX2 and GJAl genes mutations in Brazilian patients with ARS. Eight unrelated patients atfected by ARS (all of them with glaucoma and 5 without systemic malformations) and their families were ophthalmologically evaluated and had their blood collected for DNA extraction purposes. The coding regions and íntron/exon boundaries of these genes were completely evaluated through direct sequencing. Among the 8 patients, 3 (37,5%) presented with ditferent structural alterations in the FOXCl gene. A deletion in heterozygosis oftwo bases downstream the forkhead domaÍn was observed in a patient with no systemic malformations (718-719deICT). An insertion ofthree bases, also downstream the forkhead domain, was identified in a patient with systemic malformation (1359-1360insGGC). A new nonsense mutation (Trp152STOP) was identified in the forkhead domain of the FOXCl gene in another patient with ARS and systemic alterations as well. One patient harbored the mutation Ala253Val in the GJAl gene (12,5%). No mutations were identified in the PITX2 gene among these individuaIs. Patients who carried the GJAl (Ala253Val) and FOXCl (TrpI52STOP) mutations (:&om the same family) developed less severe glaucoma compared with family members presenting FOXCl (TrpI52STOP) mutation alone. Three new structural alterations of the FOXCl gene and one new mutation in the GJAl gene were described in Brazilian patients with ARS and the :&equencyof mutations in the PITX2, FOXCl and GJAl genes in this study were 0%, 37,5% and 12,5%, respectively. Despite the small number of patients, we found a slight trend to more severe glaucoma in patients with FOXCl mutations compared to those without them, except in the two patients with FOXCl and GJAl associated mutations, suggesting an attenuation effect of GJAl gene mutation (Ala253Vai). However, other studies are necessary to define the exact role ofGJAl in ARS

ASSUNTO(S)

human genetics glaucoma mutation (biology) genetica humana mutação (biologia) glaucoma

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