Identification of novel ACAN mutations in two Chinese families and genotype-phenotype correlation in patients with 74 pathogenic ACAN variations

Background: ACAN (OMIM 155760) is located on chromosome 15q26 and encodes the production of aggrecan. Aggrecan is a large chondroitin sulfate proteoglycan with a molecular weight of 254 kDa and contains 2530 amino acids. It is a critical structural component of the extracellular matrix of cartilage, including growth plate, articular, and intervertebral disk cartilage. It plays a key role in bone development. Methods: Here, we describe two pedigrees with loss-of-function variants in ACAN. Whole exome sequencing was performed for the probands from each family. We illustrate the clinical variability associated with ACAN variants. Results: The proband of pedigree A manifested short stature, relative macrocephaly, mild flat nasal bridge, low-set ears, short neck, and short thumbs. The proband of pedigree B had short height, abnormal vertebral development, and central precocious puberty. By trio-based whole exome sequencing and in silico analyses, we identified two de novo heterozygous variants of ACAN: NM_013227.4: c.116dupT, p.Arg40Glufs*51 and NM_013227.4: c.2367delC, p.Ser790Glnfs*20 (accession number: AC103982.10). Conclusion: The clinical manifestations of ACAN gene variants are diverse. ACAN gene variants are important genetic factors for short stature and should be considered as the differential diagnosis of children with idiopathic short stature (ISS).