Severe lysosomal storage disease of liver in del(1)(p36): a new presentation.

1p36 deletion is the most common terminal deletion syndrome with an estimated occurrence of 1:5000 live births. The deletion is of variable size. It usually involves less than 10 Mb in the 1pter-1p36.23 interval. Variability of the phenotype is partially related to the extent of the deletion. Some children with a 1p36 deletion were reported with obesity and hyperphagia, raising the question of possible phenotypic overlap with Prader-Willi syndrome. Correlation between presence of obesity and the size of the deletion has only been documented in one case. We report a 11-year-old girl with 1p36 deletion and the classical dysmorphological features. In late infancy, she developed an uncontrolled voracious appetite, overweight, truncal obesity and elevated serum transaminases. Liver biopsy disclosed severe steatosis. The hepatocytes contained accumulation of lipofuscins. Lipolysosomes were abnormally numerous and extremely enlarged. These features have not been previously reported in 1p36 deletion. Oligonucleotide-based microarray analysis showed a subtelomeric 2.2 Mb deletion at 1p36.33p36.32. This suggests that this chromosome segment is a critical region for obesity and hyperphagia. The accumulation in the liver with abnormal ultrastructure may be an additional feature of this form of syndromal obesity. 1p36 deletion syndrome should be considered in patients with obesity, hyperphagia and liver fat accumulation.