A Case of X-Linked Adrenal Hypoplasia Congenital (AHC) Due to Large Deletion of () and Contiguous Gene.

X-linked adrenal hypoplasia congenita (AHC) is caused predominantly by mutations in the () gene. Among these, X-linked AHC due to a large deletion of is extremely rare. In Korea, the first case was reported in 2005, and there have been no further documented cases since then. Herein, we report a unique case of X-linked AHC caused by an entire gene deletion that includes the gene and seven other genes. A seven-day-old boy presented to a pediatric endocrine clinic with prolonged postnatal jaundice, skin hyperpigmentation, hyponatremia, and hyperkalemia, suggestive of an adrenal crisis. In genetic analysis, next-generation sequencing panel for congenital adrenal hyperplasia (CAH) showed no variants. However, chromosomal microarray results revealed large deletion of Xp21.2 (29,655,007_30,765,126) including eight protein-coding genes (). In cases of atypical adrenal insufficiency and genetically undiagnosed CAH, -related AHC should be suspected, as Xp21 deletion is very rare and not detected in NGS, making microarray the best option for genetic diagnosis.