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Terminal deletions in the long arm of chromosome 4 are an uncommon event, with a worldwide incidence of approximately 0.001%. The majority of these deletions occur de novo. Terminal deletion cases are usually accompanied by clinical findings that include facial and cardiac anomalies, as well as intellectual disability. In this study, we describe the case of a 2-year-old girl, the fourth child born to consanguineous parents. While her karyotype was normal, a homozygous deletion was identified in the chromosome 4q35.2 region by subtelomeric FISH. A heterozygous deletion of the chromosome 4q35.2 region was observed in both parents. According to the literature, this is the first report of a case that has inherited a homozygous deletion of chromosome 4qter from carrier parents. Subsequent array-CGH analyses were performed on both the case and her parents. Whole-exome sequencing was also carried out to determine potential variants. We detected a NM_001111125.3:c.2329G>T (p.Glu777Ter) nonsense variant of the IQSEC2 gene in the girl, a variant that is related to X-linked intellectual disability.

Extrapontine myelinolysis is characterized by symmetric demyelination following rapid shifts in serum osmolality in the supratentorial compartment. Extrapontine myelinolysis in children is rare compared to adults. The most common underlying pathophysiology is rapid correction of hyponatremia. Only 2 cases were published after diabetic ketoacidosis without electrolyte imbalance in the English literature. This study presents an unusual and possibly the youngest case of extrapontine myelinolysis that occurred in the setting of diabetic ketoacidosis and complicated cerebral edema without electrolyte imbalance, along with a review of the literature.