Cartilage–hair hypoplasia

Cartilage–hair hypoplasia (CHH) is a rare genetic disorder characterized by short stature, fine and sparse hair, and immunodeficiency. It is a form of skeletal dysplasia and is associated with anemia and an increased risk of certain cancers.

Genetics

CHH is caused by mutations in the RMRP gene, which is located on chromosome 9. This gene is responsible for encoding a non-coding RNA component of the mitochondrial RNA processing endoribonuclease. The disorder is inherited in an autosomal recessive manner, meaning that an individual must inherit two copies of the mutated gene to be affected.

Clinical Features

Individuals with CHH typically present with short stature due to metaphyseal dysplasia, which affects the growth of long bones. Hair is often sparse, fine, and light-colored. The condition is also associated with immunodeficiency, leading to increased susceptibility to infections. Some individuals may develop anemia and have an increased risk of developing certain types of cancer, such as lymphoma and basal cell carcinoma.

Diagnosis

Diagnosis of CHH is based on clinical features, family history, and genetic testing to identify mutations in the RMRP gene. Radiographic imaging can reveal characteristic skeletal abnormalities, and blood tests can assess immune function and detect anemia.

Management

Management of CHH involves a multidisciplinary approach, including regular monitoring of growth and development, management of infections, and surveillance for malignancies. Growth hormone therapy may be considered in some cases to improve growth. Bone marrow transplantation may be an option for individuals with severe immunodeficiency.

Epidemiology

CHH is most commonly found in the Amish and Finnish populations, but it can occur in any ethnic group. The prevalence is estimated to be 1 in 23,000 in the Finnish population.

• 
  Cartilage–hair hypoplasia
• 
  Cartilage–hair hypoplasia

See also

• Skeletal dysplasia
• Immunodeficiency
• Genetic disorders

External links

• Orphanet entry on Cartilage–hair hypoplasia
• Genetics Home Reference on Cartilage–hair hypoplasia