Genetic analysis of osteogenesis imperfecta in a large Brazilian cohort.

Osteogenesis imperfecta (OI) is a genetically and clinically heterogeneous disorder caused by disruption of type I collagen synthesis. Previous Brazilian molecular OI studies have been restricted to case reports or small cohorts. The Brazilian OI Network (BOIN) is a multicenter study collecting clinical OI treatment data from five reference centers in three regions of Brazil. To describe the molecular analysis of a large cohort of OI registered at BOIN. Targeted next-generation sequencing (NGS) was performed at a centralized laboratory with the Ion Torrent platform, covering 99.6 % of the coding regions of 18 OI-associated genes. Clinical information was obtained from a clinical database. We included 156 subjects in the molecular analyses. Variants were detected in 121 subjects: 65 (53.7 %) in COL1A1 , 42 (34.7 %) in COL1A2 , 2 (1.7 %) in IFITM5 , one (0.8 %) in CRTAP , three (2.5 %) in P3H1 , two (1.7 %) in PPIB , four (3.3 %) FKBP10 , one (0.8 %) in SERPINH1 , and one (0.8 %) in TMEM38B. Ninety-one distinct variants were identified, of which 26 were novel. Of the 107 variants identified in COL1A1 and COL1A2 , 24.5 % cause mild OI, while the remaining 75.5 % cause moderate, severe, or lethal OI, of which 49.3 % are glycine to serine substitutions. A single variant in FKBP10 (c.179A>C; p.Gln60Pro) was found in three unrelated and non-consanguineous participants living in the same geographic area in Northeast Brazil, suggesting a possible founder effect. Consistent with the literature, 88.4 % of the subjects had a variant in the COL1A1 and COL1A2 genes, with 10 % inherited in an autosomal recessive manner. Notably, one variant in FKBP10 with a potential founder effect requires further investigation. Data from this large cohort improves our understanding of genotype-phenotype correlations for OI in Brazil. • This is the largest molecular analysis study of OI in Brazil. • The majority of cases a collagen I defect was found (88.4 %). • In 9.9 % an autosomal recessive gene play a role in OI. • A possible founder effect was identified in three cases with a variant in FKBP10. [ABSTRACT FROM AUTHOR]