This is one of a large number of rare metabolic disorders resulting from a deficiency in an enzyme important in the synthesis of specialized types of proteins and fats. This results in a severe generalized disorder involving many parts of the body.
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 some type of tube feeding to maintain nutrition. The amount of brain involvement is variable but most have some degree of cognitive impairment. The nature and severity of clinical problems vary widely. Motor development is impaired in most patients and muscle wasting is sometimes seen. Heart disease in the form of cardiomyopathy is common and many individuals, especially infants, develop liver disease. The sex organs, both primary and secondary may develop abnormally. Severe infections are always a threat. Older patients may develop abnormal curvature of the spine (kyphoscoliosis) and may eventually be confined to a wheelchair.
Virtually all patients have reduced vision secondary to constant eye movements and inability to focus on targets. Crossing of the eyes (strabismus) is common and a few patients have cataracts and glaucoma. There is nearly always some abnormal pigmentation of the retina in the back of the eye which causes night blindness and additional vision loss.
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.
This is one of a large group of similar errors of metabolism in which a rare enzyme defect (secondary to a gene mutation) leads to a failure of certain sugar molecules to attach to specific proteins.
This disorder is rare but the diagnosis can be made at birth based on the presence of extensive neurological problems. The diagnosis may be made by a pediatric neurologist or pediatrician with confirmation by 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. Many infants (20%) with the most severe internal organ disease (liver, heart) do not survive beyond 1 year of age. Those with milder disease may live to adulthood but require orthopedic procedures and wheelchairs. Physical, occupational, and speech therapy can be helpful. Low vision aids in selected patients may improve adaptation.