Congenital Disorder of Glycosylation, Type Iq

Background and History: 

This is one of several rare metabolic disorders resulting from a deficiency in an enzyme important in the synthesis of specialized types of proteins and fats.  The result can be a severe generalized disorder involving many parts of the body.     

Clinical Correlations: 

The major manifestations of this condition result from abnormalities in the brain, eye, and nervous system.  Infants are noted to be floppy at birth and as they grow they fail to achieve normal milestones.  Feeding problems are common and many children require tube feeding to maintain nutrition.  The amount of brain involvement is variable but most have some degree of cognitive impairment.  Other signs are thickening of the skin with excessive hair on the arms and legs.  The face is often elongated, the bridge of the nose is depressed, the ears are low and may be malformed, lips are thin, and the mouth appears large.  There is often redundant skin around the neck and face.

Often children are noted to have a defect in the iris (colored part of the eye that forms the pupil) which may extend inside the eye and even involve the optic nerve.  Sometimes the optic nerve is abnormally small.  Vision is variable and may be normal but where the optic nerve is involved, vision can be poor. 


This condition is caused by a gene mutation which must be present in both genes to result in disease.  Parents with only one copy are clinically normal but each of their children has a 25% risk of inheriting this disorder when they inherit the mutation from each parent.

Diagnosis and Prognosis: 

This disorder is rare.  The diagnosis may be made by a pediatric neurologist with the aid of gene testing.  Symptoms are highly variable and can sometimes be managed by careful adjustment of food and calorie intake.  Tube feeding may be required to achieve this.  Longevity is highly variable and ranges from infancy to adulthood.

Additional Information
Autosomal recessive