Clinical characteristics and genetic analysis of 7 children with pseudoachondroplasia

Abstract:

Objective：To analyze the clinical characteristics of children with pseudoachondroplasia（PSACH）and gene mutation sites of cartilage oligomer matrix protein（COMP）. Methods：The clinical characteristics，laboratory examination，imaging examination，gene report results and family history were collected from 7 patients diagnosed with PSACH in Jiangxi Provincial Children’s Hospital（including 4 boys and 3 girls，aged from 2 to 9 years old）. With “PSACH”，“PSEUDOACHONDROPLASIA”，“COMP gene” and “COMP” as keywords，the literature of PSACH was retrieved respectively from the PubMed，Online Mendelian Inheritance in Man（OMIM），China National Knowledge Infrastructure（CNKI） and WANFANG databases，and it was analyzed that whether the gene mutation sites of these 7 children were consistent with those reported abroad and whether there were newly developed mutations and extended gene mutation spectrum. Results：The stature of the subjects were all 3 standard deviations lower than those of children of the same age and gender，and their appearance and body shape were normal in infancy. At about 2 years old，they showed slowed growth rate and skeletal abnormalities，and walked like a duck. There were no obvious abnormalities in intelligence，face，vision and hear－ing. The X-ray film performance of the subjects were similar，including flat spinal vertebral body，prominent frontal ligule，normal intervertebral disc，shallow acetabulum development，coarse hip，broadened distal femur and stem epiphyseal end of proximal tibia and fibula，irregular shape，rough feeling，stubby long bones，blood calcium and blood phosphorus，and normal PTH metabolic indexes. Besides，all exons tests found COMP gene locus mutation，among which，2 were new mutations，and most of them were missense mutations（6/7）. The 7 patients in this study were all located in exon 8-14，including 5 in exon 13 and all located in T36~7. Conclusion：Children around 2 years old who have significant slowed growth rate，short deformity，asymmetrical limb and cartilage epiphyseal dysplasia，oblate spinal vertebral，and duck-like walking gait should be suspected with PSACH，and COMP gene check should be conducted to help diagnose. In addition，other COMP test is also a good diagnostic method. When it is difficult to diagnose PSACH through the clinical phenotype，it can be identified by exon region and domain where COMP mutation is located. PASCH is an autosomal dominant inheritance with high genetic probability. Therefore，early diagnosis and early treatment of complications are of great help to improve the quality of life and healthy birth and breeding.