is a group of severe disorders that are present from birth and affect the development of cartilage and bone. Infants with achondrogenesis usually have a small body, short arms and legs, and other skeletal abnormalities that cause life-threatening complications. There are at least three forms of achondrogenesis, type 1A, type 1B and type 2, which are distinguished by signs and symptoms, pattern of inheritance, and the results of imaging studies such as x-rays (radiology), tissue analysis (histology), and genetic testing. Type 1A and 1B achondrogenesis are both inherited in an autosomal recessive pattern. Type 1B may be caused by mutations in the SLC26A2 gene. Type 2 achondrogenesis is inherited in an autosomal dominant pattern and is caused by new (de novo) mutations in the COL2A1 gene. Source: Genetic and Rare Diseases Information Center (GARD), supported by ORDR-NCATS and NHGRI.