Achondrogenesis, type IA (ACG1A)

Achondrogenesis type IA

Achondrogenesis type IA (ACG1A; MIM 200600), also known as achondrogenesis, Houston-Harris type, is an autosomal recessive lethal skeletal dysplasia. Individuals with achondrogenesis type IA have short trunks and severe micromelia. Clinical findings include a short neck, a barrel shaped chest, flat nasal bridge, anteverted nares, and a protuberant abdomen. Hydrops fetalis is common. Radiographic findings included wedge shaped femurs with proximal metaphyseal spikes, broad and short tibiae, and short radii. The vertebral bodies, hands and feet are unossified. Additionally, the skull is poorly ossified, and the ribs are short, beaded and may be fractured. The clavicles are short and wide and the ischia and clavicles are hypoplastic. ACG1A should be differentiated from achondrogenesis type IB and achondrogenesis type II. ACG1A is caused by mutations in the thyroid hormone receptor interactor 11 gene (TRIP11). This gene encodes the Golgi microtubule-associated protein 210 (GMAP-210). GMAP-210 is required for the glycosylation and cellular transport of several matrix proteins in chondrocytes and is important for structural organization of the Golgi.