Cartilage-hair Hypoplasia

What is cartilage-hair hypoplasia?

Cartilage-hair hypoplasia is a rare genetic disorder. Other names for this condition include: cartilage-hair syndrome, CHH, McKusick type metaphyseal chrondrodysplaia, and metaphyseal chondrodysplasia – recessive type. Cartilage-hair hypoplasia is a disturbance of bone growth that was first reported in 1965. The disorder occurs most frequently in the Old Order Amish populations and in people of Finnish descent. It has been noted in other populations, but it is rare. The condition is often recognized in the newborn and sometimes prenatally on ultrasound because of the shortened extremities.

Cartilage-hair hypoplasia is an autosomal recessive inherited disorder. It is caused by mutations in a specific gene known as RMRP. Since this is an inherited autosomal recessive condition, it means that both parents carry a copy of the mutated gene; however, the parents themselves often do not have any signs or symptoms of cartilage-hair hypoplasia.

What are the symptoms of cartilage-hair hypoplasia?

Cartilage-hair hypoplasia is characterized by a specific set of signs and symptoms observed clinically and on X-rays. Short limb dwarfism occurs in patients with cartilage-hair hypoplasia. Short limb dwarfism means that the affected individual has unusually short limbs and short stature. A defect in the cartilage at the ends of the long bones affects the development of the bone itself, causing it to be short and/or malformed. Some of the individual’s joints may be hyper-flexible, especially the hands and feet, while other joints are difficult to straighten or extend, such as the elbow. The femurs (thigh bones) and tibias (shinbones) are often bowed. The hands can also be affected in appearance with malformed nails. Spinal abnormalities may also be present. Boney abnormalities including the short stature, spinal abnormalities and joint issues; these should be examined by an orthopedist on a regular basis as the child grows.

Another sign of cartilage-hair hypoplasia is a light complexion with very light-colored thin hair and eyebrows. The lighter, thinner hair comes from a lack of pigment due to the central core of the hair missing. Other visual symptoms such as dental abnormalities may be present. Individuals with cartilage-hair hypoplasia generally have normal intelligence. As a child with cartilage-hair hypoplasia grows, they meet growth milestones at the same age as other individuals without the disease.

Immunodeficiency is also a common finding in individuals with a diagnosis of cartilage-hair hypoplasia. The immunodeficiency is at a cellular level and can be mild to severe. Essentially, those with cartilage-hair hypoplasia do not have immune protection. They are at an increased risk of developing anemia, intestinal dysfunctions, autoimmune complications and opportunistic infections and illnesses that could become life threatening. People living with cartilage-hair hypoplasia also have an increased risk of developing cancer.

How is cartilage-hair hypoplasia diagnosed?

Diagnosis is made through clinical and X-ray findings as well as genetic testing. Radiographic findings include short thick tubular bones that have wide, scalloped distal metaphyses and epiphyseal changes near the femoral head, vertebral issues such as lordosis (excessive curvature of the spine also called swayback) or widening of the lumbar spine and short bullet-shaped metacarpals and phalanges.

How is cartilage-hair hypoplasia treated?

There is no cure for cartilage-hair hypoplasia. The goal of treatment is to treat the symptoms, such as infections or bony abnormalities as they arise. Effective treatment for cartilage-hair hypoplasia is a team approach. The individual often requires a group of specialists to include but not limited to pediatricians, pulmonologists, allergists, gastroenterologists, orthopedists, hematologists and geneticists.

Cartilage-hair hypoplasia treatment at the International Center for Limb Lengthening focuses on restoring normal alignment and improving functional problems that can be a result from short limb dwarfism.

Why choose the International Center for Limb Lengthening for treatment of cartilage-hair hypoplasia?

Doctors who treat cartilage-hair hypoplasia