Familial hypophosphatemia is a rare inherited disorder characterized by impaired transport of phosphate and often altered vitamin-D metabolism in the kidneys. In addition, phosphate may not be well-absorbed in the intestines. The hypophosphatemia resulting from these impairments can lead to a skeletal defect called osteomalacia, which can be considered a softening of bones. Familial hypophosphatemia also results in rickets, a childhood bone disease with characteristic bow deformities of the legs, as well as growth plate abnormalities and progressive softening of the bone as occurs in osteomalacia. In adults, the growth plate is not present so that osteomalacia is the evident bone problem. In children, growth rates may be slower than normal, frequently resulting in short stature. Familial hypophosphatemia is most often inherited as an X-linked trait. However, autosomal dominant and recessive forms of familial hypophosphatemia occur.