[Clinical and genetic investigation of 4 children with microdeletion KBG syndrome]

Objective: To analyze the genetic characteristics of clinical manifestations in children with KBG syndrome due to microdeletions. Methods: A retrospective case summary was conducted. Four children diagnosed with KBG syndrome due to 16q24.3 microdeletion at Children's Hospital of Zhengzhou University from July 2021 to April 2024 were enrolled.Their clinical manifestations, biochemical parameters, imaging data, whole-exome sequencing results, treatments and follow-up outcomes were reviewed. Results: The cohort included two males and two females (diagnosed at 81, 18, 26, and 56 months of age, respectively), from four unrelated families. All patients exhibited peculiar facial features (Cupid's bowed-shaped lips, prominent ears, thick eyebrows), skeletal abnormalities (brachydactyly, abnormal ribs, short stature, etc.), ocular anomalies (astigmatism, strabismus, amblyopia, etc.), intrauterine growth restriction, and developmental retardation. Case 2, 3, 4 had cranial imaging abnormalities, including thin anterior pituitary lobes with pineal cyst, left ventricular cyst, and abnormal pituitary stalk or lateral ventricles with sinusitis, respectively. Two children had intellectual disability, two had congenital heart disease, and one had delayed bone age and hair abnormalities. Whole exome genomic sequencing confirmed 16q24.3 microdeletions encompassing ANKRD11 gene in all four cases. Two children treated with recombinant human growth hormone achieved height increments of 1.5 s and 0.4 s, respectively. Conclusions: Typical features of 16q24.3 microdeletion-induced KBG syndrome include peculiar facial features, macrodontia, skeletal anomalies, neurological abnormalities, and ocular defects. Genetic testing is essential for definitive diagnosis. The treatment of KBG syndrome requires early diagnosis and multidisciplinary collaboration to implement individualized treatment for multisystem symptoms.