OMIM ID:
Congenital Disorder of Glycosylation, Type Ij
Alternate Names
Defective Genes
Clinical Characteristics
Ocular Features
Bilateral cataracts are present at birth. Nystagmus, strabismus, and long eyelashes have been reported.
Systemic Features
This is a disorder of glycosylation important to the formation of glycoproteins and glycolipids. Neurological signs such as tremor, clonus, and muscle fasiculations may be seen soon after birth. Other neurological abnormalities eventually include psychomotor retardation, seizures, mental retardation, hyperexcitabilty, and ataxia. Failure to thrive and feeding difficulties are evident early. Progressive microcephaly is a feature. Liver dysfunction can lead to coagulopathy and hypoproteinemia with hepatomegaly is sometimes present. Some patients have facial anomalies, inverted nipples, and subcutaneous fat pads. The MRI may show areas of brain atrophy, ischemia, and focal necrosis.
Longevity is limited with 2 of 3 reported patients dying within 2 years of life.
Genetics
Inheritance
This is a rare autosomal recessive disorder resulting from mutations in DPAGT1 (11q23.3) resulting in defective N-glycosylation. There are numerous other types of glycosylation defects with variations in the clinical manifestations.
Pedigree
Autosomal recessive
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.