Hydrolethalus syndrome

Autosomal recessive - en

Hydrolethalus syndrome (HLS) is a rare genetic disorder characterized by severe congenital malformations that are typically lethal in the neonatal period. The syndrome is inherited in an autosomal recessive manner and is most commonly reported in the Finnish population.

Clinical Features

Individuals with Hydrolethalus syndrome present with a range of severe abnormalities, including:

• Hydrocephalus: An abnormal accumulation of cerebrospinal fluid within the brain.
• Polydactyly: The presence of extra fingers or toes.
• Cleft lip and palate: A split in the upper lip and/or the roof of the mouth.
• Micrognathia: An unusually small jaw.
• Central nervous system malformations: Including holoprosencephaly, where the brain fails to divide properly into two hemispheres.

Genetics

Hydrolethalus syndrome is caused by mutations in the HYLS1 gene, which is located on chromosome 11. The HYLS1 gene is involved in the development of the ciliary body, which is essential for normal embryonic development.

Diagnosis

Diagnosis of Hydrolethalus syndrome is typically made through prenatal ultrasound findings and confirmed by genetic testing. The presence of characteristic malformations on ultrasound can prompt further genetic analysis to identify mutations in the HYLS1 gene.

Management

There is no cure for Hydrolethalus syndrome, and management is primarily supportive. Due to the severity of the malformations, most affected infants do not survive beyond the neonatal period. Prenatal diagnosis allows for informed decision-making by the parents.

Epidemiology

Hydrolethalus syndrome is most commonly reported in the Finnish population, where it has a higher incidence due to a founder effect. However, cases have been reported in other populations as well.

See Also

• Genetic disorder
• Autosomal recessive
• Hydrocephalus
• Polydactyly
• Cleft lip and palate
• Micrognathia
• Holoprosencephaly