Rhizomelic chondrodysplasia punctata type 2

Rhizomelic Chondrodysplasia Punctata Type 2

Rhizomelic Chondrodysplasia Punctata Type 2 (RCDP2) is a rare genetic disorder characterized by skeletal abnormalities, distinctive facial features, and developmental delays. It is one of the types of rhizomelic chondrodysplasia punctata, a group of peroxisomal biogenesis disorders.

Clinical Features

Individuals with RCDP2 typically present with:

• Rhizomelia: Shortening of the proximal limbs (humerus and femur).
• Chondrodysplasia punctata: Stippling of the epiphyses, visible on X-rays.
• Facial Dysmorphism: Distinctive facial features including a broad nasal bridge and a high forehead.
• Cataracts: Clouding of the lenses of the eyes, often present at birth.
• Intellectual Disability: Developmental delays and intellectual impairment.

Genetic Basis

RCDP2 is caused by mutations in the GNPAT gene, which encodes the enzyme glyceronephosphate O-acyltransferase. This enzyme is crucial for the biosynthesis of plasmalogens, a type of ether phospholipid important for normal cellular function.

Pathophysiology

The deficiency in plasmalogens due to GNPAT mutations leads to:

• Impaired development of cartilage and bone, resulting in rhizomelia and chondrodysplasia punctata.
• Neurological deficits due to abnormal brain development.
• Cataracts due to disrupted lens development.

Diagnosis

Diagnosis of RCDP2 involves:

• Clinical Evaluation: Assessment of physical and developmental features.
• Radiological Studies: X-rays showing chondrodysplasia punctata.
• Genetic Testing: Identification of mutations in the GNPAT gene.
• Biochemical Testing: Measurement of plasmalogen levels in blood or fibroblasts.

Management

There is no cure for RCDP2, and management is supportive and symptomatic:

• Orthopedic Interventions: To address skeletal abnormalities.
• Ophthalmologic Care: For cataract management.
• Developmental Support: Physical, occupational, and speech therapy.

Prognosis

The prognosis for individuals with RCDP2 is generally poor, with many affected individuals experiencing severe developmental delays and a reduced lifespan.

Research and Future Directions

Research is ongoing to better understand the pathophysiology of RCDP2 and to explore potential therapeutic approaches, including gene therapy and enzyme replacement therapy.

See Also

• Rhizomelic Chondrodysplasia Punctata Type 1
• Rhizomelic Chondrodysplasia Punctata Type 3
• Peroxisomal Disorders

External Links

• National Organization for Rare Disorders
• Genetics Home Reference

NIH genetic and rare disease info

• NIH info on Rhizomelic chondrodysplasia punctata type 2

Rhizomelic chondrodysplasia punctata type 2 is a rare disease.