Osteogenesis imperfecta IIC caused by a novel heterozygous mutation in the C-propeptide region of COL1A1

COL1A2 p.Gly1066Val variant identified in a Han Chinese family with osteogenesis imperfecta type I

Background

Osteogenesis imperfecta (OI), a genetically determined connective tissue disorder, is characterized by increased bone fragility and reduced bone mass. Clinical presentation severity ranges from very mild types with nearly no fractures to intrauterine fractures and perinatal lethality. It can be accompanied by blue sclerae, dentinogenesis imperfecta (DI), hearing loss, muscle weakness, ligament laxity, and skin fragility. This study sought to identify pathogenic gene variants in a four‐generation Han Chinese family with OI type I.

Methods

In order to unveil the molecular genetic factors underlying the disease phenotype, whole exome sequencing in a member, with OI type I, of a Han Chinese family from Hunan, China was performed. The variant identified by whole exome sequencing was further tested by Sanger sequencing in the family members.

Results

A heterozygous missense variant (NM_000089.3: c.3197G>T; NP_000080.2: p.Gly1066Val) in the collagen type I alpha 2 chain gene (COL1A2) was identified in four patients. It co‐segregated with the disease in the family.

Conclusion

The sequence variant may be a disease‐causing factor resulting in abnormal type I procollagen synthesis and leading to OI type I. This finding has significant implications for genetic counseling and clinical monitoring of high‐risk families and may be helpful for understanding pathogenic mechanism of OI and developing therapies.

A novel COL1A1 mutation in a family with osteogenesis imperfecta associated with phenotypic variabilities

Osteogenesis imperfecta (OI) is a heterogeneous disorder that is characterized by bone fragility and systemic complications, and is mainly caused by gene mutations in COL1A1 or COL1A2. A novel COL1A1 splicing mutation, c.750+2T>A, was identified in a Japanese OI family. Only the proband in this family showed various complications, such as heart valve diseases and severe scoliosis. The clinical heterogeneity in the family is discussed in this study.

Diagnostic conundrums in antenatal presentation of a skeletal dysplasia with description of a heterozygous C-propeptide mutation in COL1A1 associated with a severe presentation of osteogenesis imperfecta

Prompt and accurate diagnosis of skeletal dysplasias can play a crucial role in ensuring appropriate counseling and management (both antenatal and postnatal). When a skeletal dysplasia is detected during the antenatal period, especially early in the pregnancy, it can be associated with a poor prognosis. It is important to make a diagnosis in antenatal presentation of skeletal dysplasias to inform diagnosis, predict prognosis, provide accurate recurrence risks, and options for prenatal genetic testing in future pregnancies. Prenatal ultrasound scanning is a useful tool to detect several skeletal dysplasias and sonographic measurements serve as reliable indicators of lethality. The lethality depends on various factors including gestational age at which features are identified, size of the chest and progression of malformations. Although, it is important to type the skeletal presentation as accurately as possible, this is not always possible in an antenatal presentation and it is important to acknowledge this uncertainty. In the case of a live birth, it is always important to reassess the infant. Osteogenesis imperfecta (OI) is a heterogeneous group of disorders characterized by fragile bones. Here, we report an infant with severe OI born following a twin pregnancy in whom the bone disease is caused by a heterozygous pathogenic mutation, c.4160C >T, p.(Ala1387Val) located in the C-propeptide region of COL1A1. An assumption of lethality antenatally complicated his management in early life. We discuss this patient with particular emphasis on the neonatal presentation of a severe skeletal dysplasia and the lessons that may be learned in such situations. © 2016 Wiley Periodicals, Inc.