ESPE Abstracts

Background: Osteogenesis imperfecta (OI) is a rare congenital bone disease associated with defects in type I collagen synthesis resulting increased bone fragility, low bone mass, connective tissue manifestations and short stature. The majority of the types of OI are caused by autosomal dominant mutation in COL1A1 and COL1A2 genes. Here we showed the new, novel COL1A2 gene mutation at the heterozygous state in a family with OI.

Case: A 5-years-old boy was presented with short stature. His medical history revealed that the patient was the first child of the nonconsanguineous parents, his birth weight and height were normal, and had no bone fracture history to date. Family history revealed that his mother had also blue sclera and her arm and leg were broken ten years ago. On physical examination, his height was 98 cm (−1.42 SDS), weight was 15 kg (−1.07 SDS), he had mild blue sclera, normal teeth and had no bone deformity. On admission, the laboratory evaluation were normal, however Z score of bone mineral density of lumbar spine was −2.8. The clinical and radiological criteria supported OI type 1. The entire coding region of the COL1A1 and COL1A2 genes were analyzed by PCR-DNA direct exome sequencing. A new variant, p.Gln133Asp (c.398G>A) was found in the 9th exone of COL1A2 gene at the heterozygous state as a cause of OI. The same mutation was identified in heterozygosity in the COL1A2 gene of the patient’s mother.

Conclusion: Growth retardation is a notable symptom of OI, and additional extra-skeletal features also may manifest to a variable degree. The novel mutation reported here is a pathogenic mutation that result in OI type 1. Genotype-phenotype databases are beneficial for better genetic counselling.