Mutation characteristics in type I collagen genes in Chinese patients with osteogenesis imperfecta

Mutational analysis of COL1A1 and COL1A2 genes among Estonian osteogenesis imperfecta patients

Background

Osteogenesis imperfecta (OI) is a rare bone disorder. In 90% of cases, OI is caused by mutations in the COL1A1/2 genes, which code procollagen α1 and α2 chains. The main aim of the current research was to identify the mutational spectrum of COL1A1/2 genes in Estonian patients. The small population size of Estonia provides a unique chance to explore the collagen I mutational profile of 100% of OI families in the country.

Methods

We performed mutational analysis of peripheral blood gDNA of 30 unrelated Estonian OI patients using Sanger sequencing of COL1A1 and COL1A2 genes, including all intron-exon junctions and 5′UTR and 3′UTR regions, to identify causative OI mutations.

Results

We identified COL1A1/2 mutations in 86.67% of patients (26/30). 76.92% of discovered mutations were located in the COL1A1 (n = 20) and 23.08% in the COL1A2 (n = 6) gene. Half of the COL1A1/2 mutations appeared to be novel. The percentage of quantitative COL1A1/2 mutations was 69.23%. Glycine substitution with serine was the most prevalent among missense mutations. All qualitative mutations were situated in the chain domain of pro-α1/2 chains.

Conclusion

Our study shows that among the Estonian OI population, the range of collagen I mutations is quite high, which agrees with other described OI cohorts of Northern Europe. The Estonian OI cohort differs due to the high number of quantitative variants and simple missense variants, which are mostly Gly to Ser substitutions and do not extend the chain domain of COL1A1/2 products.

Genetic association of COL1A1 polymorphisms with high myopia in Asian population: a Meta-analysis

AIM

To comprehensively evaluate the potential association of COL1A1 polymorphisms with high myopia by a systematic review and Meta-analysis.

METHODS

All association studies on COL1A1 and high myopia reported up to June 10, 2014 in PubMed, Embase, Web of Science, and the Chinese Biomedical Database were retrieved. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were analyzed for single-nucleotide polymorphisms (SNPs) using fixed- and random- effects models according to between-study heterogeneity. Publication bias analyses were conducted by Egger's test.

RESULTS

A total of four studies from reported papers were included in this analysis. The Meta-analyses for COL1A1 rs2075555, composed of 2304 high myopia patients and 2272 controls, failed to detect any significant association with high myopia. A total of 971 cases and 649 controls were tested for COL1A1 rs2269336. The association of COL1A1 rs2269336 with high myopia was observed in recessive model (CC vs CG+GG, P=0.03) and in heterozygous model (CG vs GG, P=0.04), but not in other models.

CONCLUSION

This Meta-analysis shows that COL1A1 rs2269336 (CC vs CG+GG) affects individual susceptibility to high myopia, whereas there is no association detected between SNPs rs2075555 and high myopia. Given the limited sample size, further investigations including more ethnic groups are required to validate the association.

Mutation analysis of the COL1A1 and COL1A2 genes in Vietnamese patients with osteogenesis imperfecta

Background

The genetics of osteogenesis imperfecta (OI) have not been studied in a Vietnamese population before. We performed mutational analysis of the COL1A1 and COL1A2 genes in 91 unrelated OI patients of Vietnamese origin. We then systematically characterized the mutation profiles of these two genes which are most commonly related to OI.

Methods

Genomic DNA was extracted from EDTA-preserved blood according to standard high-salt extraction methods. Sequence analysis and pathogenic variant identification was performed with Mutation Surveyor DNA variant analysis software. Prediction of the pathogenicity of mutations was conducted using Alamut Visual software. The presence of variants was checked against Dalgleish’s osteogenesis imperfecta mutation database.

Results

The sample consisted of 91 unrelated osteogenesis imperfecta patients. We identified 54 patients with COL1A1/2 pathogenic variants; 33 with COL1A1 and 21 with COL1A2. Two patients had multiple pathogenic variants. Seventeen novel COL1A1 and 10 novel COL1A2 variants were identified. The majority of identified COL1A1/2 pathogenic variants occurred in a glycine substitution (36/56, 64.3 %), usually serine (23/36, 63.9 %). We found two pathogenic variants of the COL1A1 gene c.2461G > A (p.Gly821Ser) in four unrelated patients and one, c.2005G > A (p.Ala669Thr), in two unrelated patients.

Conclusion

Our data showed a lower number of collagen OI pathogenic variants in Vietnamese patients compared to reported rates for Asian populations. The OI mutational profile of the Vietnamese population is unique and related to the presence of a high number of recessive mutations in non-collagenous OI genes. Further analysis of OI patients negative for collagen mutations, is required.