Identification of three novel homozygous variants in COL9A3 causing autosomal recessive Stickler syndrome

BACKGROUND: Stickler syndrome (STL) is a rare, clinically and molecularly heterogeneous connective tissue disorder. Pathogenic variants occurring in a variety of genes cause STL, mainly inherited in an autosomal dominant fashion. Autosomal recessive STL is ultra-rare with only four families with biallelic COL9A3 variants reported to date. RESULTS: Here, we report three unrelated families clinically diagnosed with STL carrying different novel biallelic loss of function variants in COL9A3. Further, we have collected COL9A3 genotype–phenotype associations from the literature. CONCLUSION: Our report substantially expands the molecular genetics and clinical basis of autosomal recessive STL and provides an overview about allelic COL9A3 disorders. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13023-022-02244-6.