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Eur J Med Genet. 2013 Dec;56(12):669-73. doi: 10.1016/j.ejmg.2013.10.002. Epub 2013 Oct 17.

Two novel distinct COL1A2 mutations highlight the complexity of genotype-phenotype correlations in osteogenesis imperfecta and related connective tissue disorders.

Author information

1
Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Schwabachanlage 10, 91054 Erlangen, Germany. Electronic address: miriam.reuter@uk-erlangen.de.

Abstract

Osteogenesis imperfecta is a heritable connective tissue disorder characterized by variable symptoms including predisposition to fractures. Despite the identification of numerous mutations, a reliable genotype-phenotype correlation has remained notoriously difficult. We now describe two patients with osteogenesis imperfecta and novel, so far undescribed mutations in the COL1A2 gene, further highlighting this complexity. A 3-year-old patient presented with features reminiscent of a connective tissue disorder, with joint hypermobility, Wormian bones, streaky lucencies in the long bones and relative macrocephaly. The patient carried a heterozygous c.1316G > A (p.Gly439Asp) mutation in the COL1A2 gene located in a triple-helix region, in which glycine substitutions have been assumed to cause perinatal lethal OI (Sillence type II). A second family with type I osteogenesis imperfecta carried a heterozygous nonsense mutation c.4060C > T (p.Gln1354X) within the last exon of COL1A2. Whereas other heterozygous nonsense mutations in COL1A2 do not lead to a phenotype, in this case the mRNA is presumed to escape nonsense-mediated decay. Therefore the predicted COL1A2 propeptide lacks the last 13 C-terminal amino acids, suggesting that the OI phenotype results from decelerated assembly and overmodification of the collagen triple helix. The presented COL1A2 mutations exemplify the complexity of COL1A2 genotype-phenotype correlation in genetic counselling in OI.

KEYWORDS:

COL1A2; Genotype–phenotype correlation; Osteogenesis imperfecta

PMID:
24140640
DOI:
10.1016/j.ejmg.2013.10.002
[Indexed for MEDLINE]
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