MMP13-related Metaphyseal anadysplasia type 1 presenting with rickets-like manifestations in a family

Metaphyseal anadysplasia 1, which includes Spondyloepimetaphyseal dysplasia Missouri type, is a rare autosomal dominant skeletal dysplasia characterized by short stature, mild limb deformities, and transient metaphyseal irregularities that typically resolve with age. The condition is caused by heterozygous missense variants in the MMP13 gene, encoding matrix metalloproteinase 13, a key enzyme in endochondral ossification and extracellular matrix remodeling. Pathogenic variants in MMP13 are exceedingly rare, with only a few families reported.

We report two siblings, aged 3 and 1 years, in Sweden, presenting with clinical and radiological features consistent with Metaphyseal anadysplasia 1. Their father, of Syrian origin, exhibited short stature and mild femoral bowing. Genetic analysis revealed a novel heterozygous missense variant c.217T > C, p.(Ser73Pro) in MMP13, inherited from the affected father, and located within the same MMP13 domain as previously reported patients. The family pedigree demonstrates multiple affected individuals with short stature and bowed femurs, consistent with autosomal dominant inheritance. Radiographic imaging of father confirmed persistent but mild skeletal abnormalities.

This report expands the genotypic spectrum of Metaphyseal anadysplasia 1 and suggests a putative mutational hotspot in exon 2. It further emphasizes the importance of thorough clinical, radiological, and genetic evaluation in families with short stature and metaphyseal irregularities and a clinical long-term follow-up is proposed with regular radiographic monitoring.