Hypochondroplasia (HCH) is a developmental disorder caused by an autosomal dominant genetic defect in the fibroblast growth factor receptor 3 gene (FGFR3) that results in a disproportionately short stature, micromelia[3] and a head that appears large in comparison with the underdeveloped portions of the body.

As the infant grows, however, their arms and legs do not develop properly, and their body becomes thicker and shorter than normal.

[3] The following are characteristics consistent with this condition:[1] Hypochondroplasia is inherited as an autosomal dominant trait affecting the FGFR3 gene on chromosome 4p16.3.

[3] This gene plays an important role in embryonic development, helping to regulate activities such as cell division, migration and differentiation.

[8] The diagnosis of this condition can be done via X-rays (with lack of normal distance L1 to L5),[9] and additionally genetic testing is available to ascertain hypochondroplasia.