Communicated by Peter H. Byers We describe a dominant point mutation in the C O L l A l gene causing extremely severe osteogenesis imperfecta (01 type IMII) which was detected in the dermal fibroblasts of a proband, diagnosed by ultrasonography at 24 weeks of gestation. Type I collagen secretion was
A dominant mutation in the COL1A1 gene that substitutes glycine for valine causes recurrent lethal osteogenesis imperfecta
β Scribed by Jacky Bonaventure; Lola Cohen-Solal; Catherine Lasselin; Pierre Maroteaux
- Publisher
- Springer
- Year
- 1992
- Tongue
- English
- Weight
- 728 KB
- Volume
- 89
- Category
- Article
- ISSN
- 0340-6717
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β¦ Synopsis
Type I collagen chains of a proband from a family with recurrent lethal osteogenesis imperfecta (OI) migrated as a doublet when submitted to gel electrophoresis. Cyanogen bromide (CNBr) peptide mapping demonstrated that the post-translational over-modifications were initiated in alpha 1ICB7. Chemical cleavage of cDNA-RNA heteroduplexes identified a mismatch in the alpha 1I cDNA; this mismatch was subsequently confirmed by sequencing a 249-bp fragment amplified by the polymerase chain reaction. A G to T transition in the second base of the first codon of exon 41 resulted in the substitution of glycine 802 by valine. This mutation impaired collagen secretion by dermal fibroblasts. The over-modified chains were retained intracellularly and melted at a lower temperature than normal chains. Collagen molecules synthesized by parental fibroblasts had a normal electrophoretic mobility, but hybridization of genomic DNA with allele-specific oligonucleotides revealed the presence of the mutant allele in the mother's leukocytes. The mutation was not detected in her fibroblasts consistent with the protein data. These results support the hypothesis that somatic and germ-line mosaicism in the phenotypically normal mother explain the recurrence of OI.
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Perinatal lethal osteogenesis imperfecta (OMIM# 166210) is the result of heterozygous mutations of the COL1A1 and COL1A2 genes. Here we describe the molecular defects responsible for four cases of lethal OI. Two glycine substitutions within the COL1A1 gene (G478S, G994D) and two glycine substitution
Previous observations on mutations causing osteogenesis imperfecta (0I) suggested that unrelated patients had private mutations. Here preliminary studies on two patients with type I OI indicated that some mutations in the COL1A1 gene for type I procollagen cannot be detected by analyses of cDNAs. Th
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