Prenatal diagnosis of recessive congenital methaemoglobinaemia type II: novel mutation in the NADH‐cytochrome b5 reductase gene leading to stop codon read‐through

European Journal of Haematology - Tập 74 Số 5 - Trang 389-395 - 2005
Alena Leroux1, France Leturcq2, Nathalie Deburgrave2, Marie‐France Szajnert1
1Institut Cochin, Département Génétique, Développement et Pathologie Moléculaire, Unité 567 INSERM, Université René Descartes, Paris, France
2Laboratoire de Biochimie et de Génétique Moléculaire, Paris, France

Tóm tắt

Abstract:  A case of type II recessive congenital methaemoglobinaemia (RCM) observed in a Lebanese subject with a novel mutation in NADH‐cytochrome b5 reductase gene is described. A homozygous mutation CAC to AA identified at Thr 295 with an out‐of‐frame 1‐bp deletion leads to a frameshift with translational read‐through of the natural stop codon. The molecular mechanism is demonstrated by an in vitro translation study. The model of mutated cytochrome b5 reductase protein possessing 46 additional amino acids was obtained by homology modelling. The mutation causes an alteration of hydrophobicity in the carboxyl‐terminal portion, resulting in the conformation being drastically disturbed by the presence of 46 supplementary amino acids. The identical mutation was found in the heterozygous state in the patient's parents and sister. Identification of this new mutation enabled us to perform the molecular prenatal diagnosis of type II RCM at the DNA level.

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