Expanding the Clinical Spectrum of KIDAR Syndrome: A Case of Multisystemic Involvement in a Palestinian Child with AP1B1 Deficiency.

KIDAR syndrome (AP1B1-deficiency syndrome) is an ultra-rare autosomal recessive disorder characterized by ichthyosis, sensorineural deafness, and developmental delay, with fewer than 15 molecularly confirmed cases reported worldwide. We describe a 2.5-year-old Palestinian boy with a homozygous frameshift variant in AP1B1 (p.Leu166TrpfsTer38) who presented with the classic phenotype in addition to persistent vomiting and severe enteropathy, hyperparathyroidism, subclinical hypothyroidism, and progressive elevations in hepatic transaminases. His presentation overlaps with previously reported cases while further illustrating the persistence and complexity of gastrointestinal and endocrine involvement in KIDAR syndrome. This case underscores the importance of early genetic confirmation, coordinated multidisciplinary care, and continued case aggregation to refine the phenotype and guide management of this ultra-rare disorder.