UCD.- Citrullinemia type II (CTLN2) Adult onset.
Incidence
It is an autosomal recessive disease. Most of the reports of the late-onset form appeared in Japanese journals.
Clinical Characteristics
Citrullinemia is an autosomal recessive disease caused by a deficiency of argininosuccinate synthetase and characterized primarily by elevated serum and urine citrulline levels. Citrullinemia type II (CTLN2) is caused by citrin deficiency resulting from mutations in SLC25A13 on chromosome 7q21.3, which encodes the mitochondrial solute carrier protein, citrin. Citrin deficiency leads to failure to shuttle aspartate and glutamate from and to the mitochondrion, leading to a mild hyperammonemia and citrullinemia. In Japan a distinct late-onset form of citrullinemia was reported. Significant clinical abnormality had onset in childhood or not until adulthood, age 48 years in 1 case. Symptoms included enuresis, delayed menarche, insomnia, sleep reversal, nocturnal sweats and terrors, recurrent vomiting (especially at night), diarrhea, tremors, episodes of confusion after meals, lethargy, convulsions, delusions, hallucinations, and brief episodes of coma. Delayed mental and physical development was shown by some patients. Most had a peculiar fondness for beans, peas, and peanuts from early childhood and a dislike for rice, other vegetables, and sweets. Since the preferred foods are high in arginine, the dietary predilection of these patients may reflect an arginine deficiency. As the patients get older, episodic disturbances become more frequent, and bizarre behavior, including manic episodes, echolalia, and frank psychosis, appears. Citrulline concentrations in the plasma were increased. The late-onset form is apparently autosomal recessive because sibs have been affected and some of the parents have been consanguineous. Most of the reports of the late-onset form appeared in Japanese journals. In the study of adult-onset type II citrullinemia in Japanese, Yasuda et al. (2000) found that the onset of serious and recurring symptoms in CTLN2 varied from age 11 to age 79, with a mean of 34.4 years. Almost all patients suffered from a sudden disturbance of consciousness associated with disorientation, restlessness, drowsiness, and coma, and most died mainly of cerebral edema within a few years of onset.
Precipitants
Meals rich in proteins usually precipitate episodes of confussion and disorientation, restlessness, drowsiness, and coma.
Provocation Tests
None bur protein ingestion increse abnormal lab results.