Identification of a novel heterozygous mutation of ACAN in a Korean family with proportionate short stature

Aggrecan is a proteoglycan in the extracellular matrix of growth plate and cartilaginous tissues. Aggrecanopathy has been reported as a genetic cause not only for severe skeletal dysplasia but also for autosomal dominant short stature with normal to advanced bone age. We report a novel heterozygous mutation of ACAN in a Korean family with proportionate short stature identified through targeted exome sequencing. We present a girl of 4 years and 9 months with a family history of short stature over three generations. The paternal grandmother is 143 cm tall (−3.8 as a Korean standard deviation score [SDS]), the father 155 cm (−3.4 SDS), and the index case 96.2 cm (−2.9 SDS). Evaluation for short stature showed normal growth hormone (GH) peaks in the GH provocation test and a mild delayed bone age for chronological age. This subject had clinical characteristics including a triangular face, flat nasal bridge, prognathia, blue sclerae, and brittle teeth. The targeted exome sequencing was applied to detect autosomal dominant growth palate disorder. The novel variant c.910G>A (p.Asp304Asn) in ACAN was identified and this variant was found in the subject's father using Sanger sequencing. This is the first case of Korean familial short stature due to ACAN mutation. ACAN should be considered for proportionate idiopathic short stature, especially in cases of familial short stature.

Familial short stature caused by ACAN gene mutation:a familial case report / 临床儿科杂志

Objective To explore the clinical phenotype and genetic variation of familial short stature. Method The clinical data of a familial short stature pedigree in Guangxi Zhuang autonomous region were retrospectively analyzed. The disease-causing gene was identified using targeted high-throughput sequencing combined with Sanger sequencing in May 2017. The related literature were searched and the relationship between the clinical phenotype and genotype of the ACAN gene mutation were summarized. Results The two patients were brothers, one was 9-year and 10-month old boy and the other was 7-year-old boy. Both of them had short stature. Their parents were non-consanguineous marriage and both were 150 cm in height, with. Their uncle and grandpa are also short stature. Gene sequencing revealed a novel heterozygous variation c.6193delC (p.Gln2065Serfs*27) in exon 12 of ACAN gene in both brothers, which were inherited from their father. No report of this mutation was found by searching literature and databases. A total of 11 related articles in English were retrieved. Totally (including our study) 32 patients in 41 families were reported to have the pathogenic variants of ACAN gene, including 4 variants from Chinese children, but no such reports were found in Chinese literatures. The most common clinical manifestation is idiopathic short stature, which is mostly familial but could also be sporadic. Some children also suffered from osteoarthritis, disc herniation or degeneration. Most of the children had advanced bone age, but some of them were normal or even lagged. Treatment of postponing puberty by growth hormone combined with gonadotropin-releasing hormone analogues can effectively improve final height. Conclusion Heterozygous mutation of ACAN gene can cause short stature in children and has significant familial genetic characteristics, and the clinical characteristics have no relationship with genotypes.