Two new reported cases of 16q22.3q23.3 duplication syndrome

Two new reported cases of 16q22.3q23.3 duplication syndrome and intrafamilial variability.

The authors report a 15-year-old male with developmental delay, attention deficit disorder, autism, dysmorphic features (midface hypoplasia, prognathism), absence seizures, leg discrepancy (left leg being shorter than the right one) leading to scoliosis, and polymicrogyria. As a child he had surgeries for hydrocephalus, heart defect (patent ductus arteriosus) and inguinal hernia. Cytogenetic examination showed a duplication of an 8.85 Mb segment of the long arm of chromosome 16 (16q22.3q23.3). This abnormality was caused by an insertion ins(5;16)(p15.3;q22.3q23.3) in his mother. Similar manifestations were reported in several other patients with a duplication of this segment of 16q. The patient has an older sister with exactly the same karyotype, but she is intellectually normal and does not have any physical abnormalities (although she suffers from anxiety). The reasons for drastically different manifestations in siblings having exactly the same abnormality are unknown. The authors believe that this discrepancy may be related to the patients’ sex, where males are more severely affected. The third child in this family with intellectual disability, genitourinary abnormalities and gastro-esophageal reflux has a deletion of this segment 16q22.3q23.3.

Gunther K. et al. “Two new reported cases of 16q22.3q23.3 duplication syndrome highlight intrafamilial variability and potential sex expression differences within a rare duplication syndrome”. “Clinical Case Reports” 2021, v. 9 (3), 1629-1633.

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