BACKGROUND: Osteogenesis imperfecta (OI) is a group of hereditary disorders 
characterized by low bone mass and recurrent fractures. Most OI cases follow an 
autosomal dominant pattern of inheritance and are attributed to mutations in 
genes encoding type I collagen (COL1A1/COL1A2). Genomic structural variations 
involving type I collagen genes are extremely rare in OI.
CASE REPORT: In this study, we characterized a de novo balanced translocation of 
t(5;7)(q32;q21.3) that caused an extremely rare type of OI in a patient from a 
non-consanguineous family. The clinical phenotypes of this OI included recurrent 
fractures, low bone mass, macrocephaly, blue sclera and failure to thrive. 
Next-generation sequencing was used to identify the translocation, and Sanger 
sequencing was used to validate and map the breakpoints. The breakpoint on 
chromosome 7 disrupted the COL1A2 gene in the 17th exon, presumed to affect type 
I collagen production and give rise to OI. The breakpoint on chromosome 5 
disrupted the protein phosphatase 2 regulatory subunit B, beta gene (PPP2R2B) 
within the first intron.
CONCLUSIONS: This is the first report of a copy-neutral structural variant 
involving COL1A2 that leads to a rare type of OI. This study expands the 
genotypic spectrum of OI and demonstrates the effectiveness of targeted 
sequencing for breakpoint mapping.