Johanson–Blizzard syndrome

Johanson-Blizzard syndrome

Johanson–Blizzard syndrome

Johanson–Blizzard syndrome (JBS) is a rare autosomal recessive genetic disorder characterized by a range of congenital abnormalities. It was first described by Ann Johanson and Robert M. Blizzard in 1971. The syndrome affects multiple systems in the body, leading to a variety of clinical manifestations.

Clinical Features

Individuals with Johanson–Blizzard syndrome typically present with the following features:

• Pancreatic insufficiency: This is a hallmark of JBS and leads to malabsorption and failure to thrive.
• Nasal alar hypoplasia: Underdevelopment of the nasal alae, giving the nose a beak-like appearance.
• Sensorineural hearing loss: Many individuals with JBS have significant hearing impairment.
• Intellectual disability: Varying degrees of intellectual disability are common.
• Growth retardation: Affected individuals often have short stature.
• Dental anomalies: These may include missing teeth or other dental abnormalities.
• Scalp defects: Areas of missing skin or hair on the scalp.

Genetics

Johanson–Blizzard syndrome is caused by mutations in the UBR1 gene, which is located on chromosome 15q15-q21. The UBR1 gene encodes a protein that is part of the N-end rule pathway, which is involved in protein degradation. Mutations in this gene disrupt normal protein degradation, leading to the various manifestations of the syndrome.

Diagnosis

Diagnosis of Johanson–Blizzard syndrome is based on clinical features and can be confirmed by genetic testing to identify mutations in the UBR1 gene. Prenatal diagnosis is possible if the mutation is known in the family.

Management

There is no cure for Johanson–Blizzard syndrome, and treatment is symptomatic and supportive. Management strategies include:

• Enzyme replacement therapy for pancreatic insufficiency.
• Hearing aids or cochlear implants for hearing loss.
• Special education and developmental support for intellectual disability.
• Regular monitoring and treatment of growth and nutritional status.

Prognosis

The prognosis for individuals with Johanson–Blizzard syndrome varies depending on the severity of the symptoms and the effectiveness of the management strategies. Early diagnosis and intervention can improve the quality of life for affected individuals.

Related Pages

• Autosomal recessive disorder
• Pancreatic insufficiency
• Sensorineural hearing loss
• Intellectual disability
• Genetic testing