ALG6-congenital disorder of glycosylation
ALG6-congenital disorder of glycosylation is an inherited condition that disrupts the essential process of glycosylation, affecting multiple body systems and hormone production.
Overview
ALG6-congenital disorder of glycosylation (ALG6-CDG), also known as congenital disorder of glycosylation type Ic, is an inherited condition that affects many parts of the body. Signs and symptoms vary widely and typically develop during infancy.
Symptoms
Common signs and symptoms include:
- Failure to thrive (difficulty gaining weight and growing at the expected rate)
- Weak muscle tone (hypotonia) and developmental delay
- Seizures
- Problems with coordination and balance (ataxia)
- Stroke-like episodes involving extreme lack of energy (lethargy) and temporary paralysis
- Blood clotting disorders
- Eye abnormalities, including eyes that do not look in the same direction (strabismus) and retinitis pigmentosa, which causes vision loss
- In females, hypergonadotropic hypogonadism, which affects sexual development and often prevents puberty
Causes
ALG6-CDG is caused by mutations in the ALG6 gene. This gene produces an enzyme necessary for glycosylation—the process of adding sugar molecules to proteins and fats to enable their proper function. Mutations result in an abnormal enzyme with reduced or no activity, leading to incomplete glycosylation. This impairment affects the function of organs and tissues, including the nervous system, liver, intestines, and the hormone-producing (endocrine) system.
Inheritance
This condition is inherited in an autosomal recessive pattern, meaning both copies of the gene in each cell contain mutations. Parents of an affected individual each carry one copy of the mutated gene but typically do not exhibit symptoms.