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Orientador(es)
Resumo(s)
Shwachman–Diamond syndrome (SDS) is caused by mutations in the SBDS gene, most of which are the result of gene conversion events
involving its highly homologous pseudogene SBDSP. Here we describe the molecular characterization of the first documented gross deletion in the SBDS gene, in a 4-year-old Portuguese girl with SDS. The clinical diagnosis was based on the presence of hematological symptoms (severe anemia and cyclic neutropenia), pancreatic exocrine insufficiency and skeletal abnormalities. Routine molecular screening revealed heterozygosity for the common splicing mutation c.258+2T>C, and a further step-wise approach led to the detection of a large deletion encompassing exon 3, the
endpoints of which were subsequently delineated at the gDNA level. This novel mutation (c.258+374_459+250del), predictably giving rise to an internally deleted polypeptide (p.Ile87_Gln153del), appears to have arisen from an excision event mediated by AluSx elements which are present
in introns 2 and 3.
Our case illustrates the importance of including gross deletion screening in the SDS diagnostic setting, especially in cases where only one deleterious mutation is detected by routine screening methods. In particular, deletional rearrangements involving exon 3 should be considered, since Alu sequences are known to be an important cause of recurrent mutations.
Descrição
Palavras-chave
Shwachman-Diamond syndrome SBDS gene SDS Anemia Neutropenia Pancreatic insufficiency Gross deletion
Contexto Educativo
Citação
Costa, Elísio; Duque, Frederico; Oliveira, Jorge; Garcia, Paula; Gonçalves, Isabel; Diogo, Luisa; Santos, Rosário (2007). Identification of a novel AluSx-mediated deletion of exon 3 in the SBDS gene in a patient with Shwachman-Diamond syndrome. Blood Cells, Molecules, and Diseases. ISSN 1079-9796. 39:1, p. 96–101