A Complex Case of Koolen-De Vries Syndrome Associated with Hypopituitarism and Type 1 Diabetes Mellitus.

Complex diseases arise from the interplay of genetic and environmental factors. We present a case where complex diseases seem to coexist. A 12-month-old girl was referred for short stature and hypotonia. Initial evaluation revealed central hypothyroidism, growth hormone deficiency and a small pituitary gland with ectopic neurohypophysis. Replacement therapy improved growth, but developmental delay and strabismus ensued. At age 10, she experienced a first seizure treated with levetiracetam. At age 12, she presented diabetic ketoacidosis and functional insulin therapy was started; positive autoantibodies confirmed autoimmune etiology. Initial genetic testing performed by microarray analysis retrieved normal results, but exome sequencing revealed a heterozygous pathogenic variant in KANSL1 gene, allowing for the diagnosis of Koolen-de Vries syndrome. In this patient, Koolen-de Vries syndrome presented initially as hypopituitarism and only later epilepsy. Afterwards, type 1 diabetes mellitus ensued, highlighting the complexity of intertwined conditions.