Achondrogenesis type 2

Achondrogenesis Type 2

Diagram of autosomal dominant inheritance pattern

Achondrogenesis Type 2 is a rare genetic disorder characterized by severe dwarfism, skeletal dysplasia, and other developmental abnormalities. It is one of the most severe forms of osteochondrodysplasia, a group of disorders affecting the development of bone and cartilage.

Etiology

Achondrogenesis Type 2 is caused by mutations in the COL2A1 gene, which encodes the alpha-1 chain of type II collagen. This gene is crucial for the normal development of cartilage and bone. The disorder follows an autosomal dominant inheritance pattern, meaning a single copy of the mutated gene can cause the condition.

Clinical Features

Individuals with Achondrogenesis Type 2 typically present with:

• Severe short stature
• Disproportionately short limbs
• A small chest with short ribs
• A prominent abdomen
• Hydrops fetalis
• Polyhydramnios during pregnancy

The condition is often detected prenatally through ultrasound due to the characteristic skeletal abnormalities.

Diagnosis

Diagnosis of Achondrogenesis Type 2 is based on clinical features, radiographic findings, and genetic testing. Radiographs typically show:

• Poor ossification of the spine and pelvis
• Short and broad long bones
• A small thoracic cavity

Genetic testing can confirm mutations in the COL2A1 gene.

Management

There is no cure for Achondrogenesis Type 2, and management is primarily supportive. Due to the severity of the condition, many affected infants are stillborn or die shortly after birth. Supportive care may include:

• Respiratory support
• Nutritional support
• Genetic counseling for the family

Prognosis

The prognosis for Achondrogenesis Type 2 is poor, with most affected individuals not surviving beyond the neonatal period. The condition is often lethal due to respiratory insufficiency resulting from the small thoracic cavity.

Related Pages

• Osteochondrodysplasia
• Dwarfism
• Collagen
• Genetic disorders