Clinical characteristics of pseudoachondroplasia and analysis of COMP gene mutation

Objective This article reported the clinical characteristics and gene mutations of two pseudoachondroplasia cases, and made a literature review in order to improve clinicians′ understanding of the disease. Methods Clinical features of two patients who were short stature accompanied with skeletal deformities were summarized, and they accepted whole exome sequencing. We also reviewed literature to summarize the clinical characteristics and known gene research progress of all reported Chinese pseudoachondroplasia cases. Results The two patients′ clinical characteristics were short limbdwarfism with skeletal deformity. Genetic results showed that there were two heterozygous mutations in the cartilage oligomeric matrix protein (COMP) gene of the two patients, c. 1417_1419delGAC and c. 1552G>A, respectively. Up to March 2019, a total of 58 cases of pseudoachondroplasia have been reported in China. The median height of these patients is -5.03 SDS. The clinical features include abnormal gait, short limbs, short fingers/toes, scoliosis, bracelet sign, ankle sign and other skeletal deformities. COMP is the pathogenic gene and mutations mainly located in calmodulin-like domains. The hotspot mutation is c. 1417_1419delGAC. Conclusions Pseudoachondroplasia is a kind of rare genetic disease characterized by short stature and skeletal deformities. The clinical and genetic characteristics of the disease were summarized, which may improve the early diagnosis rate. Key words: Pseudoachondroplasia; Cartilage oligomeric matrix protein; Gene mutation; Molecular mechanism