Multiple congenital anomalies-hypotonia-seizures syndrome type 2

Alternate names

MCAHS2; Early infantile epileptic encephalopathy 20; MCAHS type 2

Definition

Multiple congenital anomalies-hypotonia-seizures syndrome type 2 (MCAHS2) is a genetic neurodevelopmental disorder characterized by distinctive facial features, low muscle tone (hypotonia) at birth, myoclonic seizures (which cause jerks or twitches of the upper body, arms, or legs), and various other problems involving the central nervous system, heart, and urinary system.

Cause

This condition is caused by mutations in the PIGA gene on the X chromosome.

Inheritance

X-linked recessive inheritance

It inheritance is X-linked recessive, so it typically affects boys. However, in some cases, MCAHS2 is not inherited from a parent and is the result of a new mutation occurring for the first time in a person with MCAHS2 (a de novo mutation).

Signs and symptoms

This condition is characterized by distinctive facial features, low muscle tone (hypotonia) at birth, myoclonic seizures (which cause jerks or twitches of the upper body, arms, or legs), and various other problems involving the central nervous system, heart, and urinary system. Specific symptoms (especially those not involving the nervous system) and severity vary from person to person, but most children develop severe developmental delay and intellectual disability.

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. 5%-29% of people have these symptoms

• Cirrhosis(Scar tissue replaces healthy tissue in the liver)
• Duplicated collecting system
• Elevated alkaline phosphatase(Greatly elevated alkaline phosphatase)
• Hepatomegaly(Enlarged liver)
• Ichthyosis
• Polyhydramnios(High levels of amniotic fluid)
• Seborrheic dermatitis
• Vesicoureteral reflux

1%-4% of people have these symptoms

• Atrial septal defect(An opening in the wall separating the top two chambers of the heart)

Diagnosis

Molecular Genetics Tests

• Sequence analysis of the entire coding region
• Targeted variant analysis
• Deletion/duplication analysis
• Detection of homozygosity
• Sequence analysis of select exons

Treatment

Treatment depends on the symptoms present and aims to control symptoms and increase quality of life. The long-term outlook and life expectancy varies depending on severity. Some children with MCAHS2 do not survive beyond infancy.

NIH genetic and rare disease info

• NIH info on Multiple congenital anomalies-hypotonia-seizures syndrome type 2

Multiple congenital anomalies-hypotonia-seizures syndrome type 2 is a rare disease.

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