Hoyeraal–Hreidarsson syndrome

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Hoyeraal–Hreidarsson syndrome
Synonyms	HHS
Pronounce
Specialty	Medical genetics
Symptoms	Cerebellar hypoplasia, immunodeficiency, pancytopenia, developmental delay
Complications	N/A
Onset	Infancy
Duration	Chronic
Types	N/A
Causes	Mutations in the DKC1 gene
Risks
Diagnosis	Genetic testing, clinical evaluation
Differential diagnosis	Dyskeratosis congenita, ataxia-telangiectasia
Prevention
Treatment	Hematopoietic stem cell transplantation, supportive care
Medication
Prognosis	Poor
Frequency	Rare
Deaths

Hoyeraal–Hreidarsson syndrome (HHS) is a rare, severe variant of Dyskeratosis congenita (DC), a disorder that can affect many parts of the body. HHS is characterized by cerebellar hypoplasia, severe immunodeficiency, intrauterine growth retardation, and microcephaly.

Symptoms

The symptoms of Hoyeraal–Hreidarsson syndrome include:

• Microcephaly: A condition where the head size is significantly smaller than that of other people of the same age and sex.
• Intrauterine growth retardation: This is a condition where a baby grows more slowly than normal during its time in the womb.
• Cerebellar hypoplasia: This is a neurological condition in which the cerebellum is smaller than usual or not completely developed.
• Severe immunodeficiency: This is a state where the immune system's ability to fight infectious disease and cancer is compromised or entirely absent.

Causes

Hoyeraal–Hreidarsson syndrome is caused by mutations in the DKC1, NOP10, NHP2, TERT, TCAB1, or TINF2 genes. These genes are involved in the maintenance of telomeres, which are structures found at the ends of chromosomes that protect them from damage.

Diagnosis

Diagnosis of Hoyeraal–Hreidarsson syndrome is based on the presence of characteristic symptoms and confirmed by genetic testing.

Treatment

Treatment of Hoyeraal–Hreidarsson syndrome is focused on managing the symptoms and may include bone marrow transplant for the bone marrow failure and immunodeficiency.

Prognosis

The prognosis for individuals with Hoyeraal–Hreidarsson syndrome is generally poor, with most individuals not surviving past childhood.

See also

• Dyskeratosis congenita
• Bone marrow transplant
• Microcephaly
• Intrauterine growth retardation
• Cerebellar hypoplasia
• Severe immunodeficiency