Anauxetic dysplasia (ANXD1) is a form of spondylometaepiphyseal dysplasia characterized by the prenatal onset of extreme short stature, an adult height of less than 85 cm, hypodontia, and mild mental retardation. Major radiographic characteristics are late-maturing ovoid vertebral bodies with concave dorsal surfaces in the lumbar region; small capital femoral epiphyses; hypoplastic femoral necks; hypoplastic iliac bodies and shallow acetabulae; irregular metaphyseal mineralization and demarcation of the long tubular bones; short first and fifth metacarpals with widened shafts; very short and broad phalanges with small, late-ossifying epiphyses and bullet-shaped middle phalanges; and midface hypoplasia. The number of chondrocytes is severely reduced in the resting and proliferating cartilage, with diminished columnization of the hypertrophic zone (summary by Thiel et al., 2005).
Mutations in RMRP also cause 2 milder types of short stature with susceptibility to cancer, cartilage-hair hypoplasia (CHH; 250250) and metaphyseal dysplasia without hypotrichosis (250460).
Genetic Heterogeneity of Anauxetic Dysplasia
Anauxetic dysplasia-2 (ANXD2; 617396) is caused by mutation in the POP1 gene (602486) on chromosome 8q22. ANXD3 (618853) is caused by mutation in the NEPRO gene (617089) on chromosome 3q13. [from
OMIM]