NORD gratefully acknowledges Miia Melkoniemi, MD, PhD, Department of Anesthesia, Tampere University Hospital, Finland, for assistance in the preparation of this report.
Homozygous OSMED (oto-spondylo-megaepiphyseal dysplasia) is an extremely rare genetic disorder characterized by malformation (dysplasia) of certain bones, hearing loss and distinct facial features. Skeletal malformations affect the bones of the arms, legs and spines eventually resulting in disproportionate short stature. Hearing loss is often severe. Intelligence is normal. Homozygous OSMED occurs because of disruptions or changes (mutations) to the COL11A2 gene and is inherited as an autosomal recessive trait.
Two additional disorders, Weissenbacher-Zweymuller syndrome and Stickler syndrome III, more commonly known as non-ocular Stickler syndrome, are also caused by mutations to this gene (allelic disorders). Some clinical researchers believe that each of these three disorders is a separate and distinct entity. Others believe that the three represent a range of severity of one syndrome. Regardless, these disorders involve alterations (mutations) of the collagen gene, COL11A2. Some researchers have suggested that the name OSMED be used as a general heading to consist of "heterozygous OSMED," which encompasses Weissenbacher-Zweymuller syndrome and Stickler syndrome type III and is inherited as an autosomal dominant trait, and "homozygous OSMED," which encompasses autosomal recessive cases of oto-spondylo-megaepiphyseal dysplasia.
Please note that some of these organizations may provide information concerning certain conditions potentially associated with this disorder (e.g., hearing loss, short stature).
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