Читать книгу The SAGE Encyclopedia of Stem Cell Research - Группа авторов - Страница 316
Genetic Abnormalities
ОглавлениеAchondroplasia is the most common disease of the growth plate and is a major cause of dwarfism. It is caused by a mutation in the FGF receptor 3 (FGFR3) that causes constitutive activation of the gene and thereby suppresses growth. This dwarfing condition is an autosomal dominant disorder, which causes an abnormal proliferation and maturation of chondrocytes. Affected individuals have shortened proximal extremities, a trunk of normal length, and an enlarged head with bulging forehead and depression of the root of the nose. The primary defect in patients with achondroplasia is abnormal endochondral ossification. Tubular bones are short and broad, indicating normal periosteal growth. The iliac crest apophyses are normal, while the growth of the triradiate cartilage is abnormal. This gives rise to horizontal acetabular roofs. These patterns of defect help explain the clinical and radiographic characteristics of achondroplasia.
A similar condition, called hypochondroplasia is also a form of short-limbed dwarfism. Hypochrondroplasia interferes with the ossification process, affecting the conversion of cartilage into bone. This is significantly seen in the long bones of arms and legs, with the adult height for men ranging from 138 centimeters (cm) to 165 cm. The obvious clinical features include short stature, stocky build, rhizomelia, micromelia, generalized mild joint laxity, and macrocephaly. Recent studies are targeting stem cell transplantation to shorten the treatment period of patients with achondroplasia and hypochrondroplasia. Stem cells, once differentiated, could be used to correct similar conditions in which cartilage cells are deficient in number or function.