Hydrolethalus syndrome

Editor-In-Chief: Prab R Tumpati, MD
Obesity, Sleep & Internal medicine
Founder, WikiMD Wellnesspedia &
W8MD's weight loss doctor NYC
Philadelphia GLP-1 weight loss and GLP-1 clinic NYC

Hydrolethalus syndrome
Synonyms	HLS
Pronounce	N/A
Specialty	N/A
Symptoms	Hydrocephalus, polydactyly, cleft lip and palate, central nervous system malformations
Complications	N/A
Onset	Prenatal
Duration	Lifelong
Types	N/A
Causes	Mutations in the HYLS1 gene
Risks	Consanguinity
Diagnosis	Prenatal diagnosis, genetic testing
Differential diagnosis	Meckel syndrome, Smith-Lemli-Opitz syndrome
Prevention	N/A
Treatment	Supportive care
Medication	N/A
Prognosis	Poor, often lethal in infancy
Frequency	Rare
Deaths	N/A

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