An abnormal shortening of the femur.

Underdevelopment of the humerus.

Increased width of the distal part of the shaft (metaphysis) of the femur.

Disproportionate shortening of the proximal segment of limbs (i.e. the femur and humerus).

A severe degree of short stature, more than -4 SD from the mean corrected for age and sex.

An abnormally short femoral neck (which is the process of bone, connecting the femoral head with the femoral shaft).

A flattened vertebral body shape with reduced distance between the vertebral endplates.

Underdevelopment of the femoral head.

A reduction in the freedom of movement of one or more joints.

Congenital dysplasia of the hip (CDH) is an abnormality of the seating of the femoral head in the acetabulum. Its severity ranges from mild instability of the femoral head with slight capsular laxity, through moderate lateral displacement of the femoral head, without loss of contact of the head with the acetabulum, up to complete dislocation of the femoral head from the acetabulum. It is one of the most common skeletal congenital anomalies (summary by Sollazzo et al., 2000). Acetabular dysplasia is an idiopathic, localized developmental dysplasia of the hip that is characterized by a shallow hip socket and decreased coverage of the femoral head. Its radiologic criteria include the center-edge angle of Wiberg, the Sharp angle, and the acetabular roof obliquity. Most patients with acetabular dysplasia develop osteoarthritis (165720) after midlife, and even mild acetabular dysplasia can cause hip osteoarthritis (summary by Mabuchi et al., 2006). CDH occurs as an isolated anomaly or with more general disorders represented by several syndromes and with chromosomal abnormalities such as trisomy 18 (Wynne-Davies, 1970). Genetic Heterogeneity of Developmental Dysplasia of the Hip Developmental dysplasia of the hip-1 (DDH1) maps to chromosome 13q22; DDH2 (615612) maps to chromosome 3p21. DDH3 (620690) is caused by mutation in the LRP1 gene (107770) on chromosome 12q13.