NGLY1 deficiency (NORD)

NGLY1 deficiency is a rare genetic disorder affecting multiple parts of the body due to a deficiency of the enzyme N-glycanase.

Enzymes are proteins which help speed up chemical reactions in the body and N-glycanase speeds up the removal of sugar chains from proteins.

Without this process, proteins do not function normally and misshaped ones may accumulate. NGLY1 deficiency is a chronic condition that presents during infancy and early childhood.

NGLY1 deficiency has a number of characteristic symptoms, although the specific symptoms a patient experiences are often unique to the individual.

Most infants and children with NGLY1 deficiency do not grow or develop as expected. Symptoms may include low birthweight, a smaller than expected head circumference, and missing developmental milestones, such as walking or talking.

Intellectual disability is also common. Many affected individuals have motor problems including shaking and uncontrollable movements, which can range from slight tremors while trying to do fine motor skills like writing, to an uncontrolled sometimes painful jerky movement.

Skeletal abnormalities may also occur such as small hands or feet, frequently broken bones, uneven shoulders or hips, difficulty standing up straight, and dislocated joints.

Some patients develop seizures which can start as early as two months of age. Individuals with NGLY1 deficiency often will not produce tears when crying.

This in turn may cause other complications, such as scarring and ulcers in the eyes, painful or irritated eyes, and poor vision. Lastly, liver problems may arise in children with NGLY1 deficiency.

NGLY1 deficiency is caused by changes or mutations in the NGLY1 gene, and follows an autosomal recessive inheritance pattern.

This means that both copies of the NGLY1 gene must be mutated for an individual to have the disorder. The mutated NGLY1 gene causes the N-glycanase enzyme to be dysfunctional or be completely absent.

N-glycanase’s role is to speed up the process of removing sugar molecules from proteins. Removing sugar molecules from damaged proteins allows them to be recycled.