Objective: We present a postnatal diagnosis of 17q12 micro-duplication with no obvious phenotypic abnormality.
Case review: A female newborn weighing 2058 g was delivered NVD at 34+5 weeks of gestation to a Gravida 3 Para 2 23 year old mother, who had an antenatal history of significant maternal polyhydraminos. The baby was born flat and cyanosed with an APGAR score of 3.
Discussion: The chromosomal microarray analysis revealed a copy number gain (4 copies) of “unknown significance” of the long arm of chromosome 17 at 17q12 of size 431 kbp and encompassing 7 OMIM genes. The result also showed stretches of LOH (loss of hetrozygosity) on several chromosomes. The mitochondrial genome analysis identified a heterozygous likely pathogenic variant in the ANKRD11 gene. This result is consistent with the genetic diagnosis of autosomal dominant KBG syndrome. Physical examination revealed edema and ascites. The baby had no major dysmorphic features.
Conclusion: The 17q12 microduplication can demonstrate distinctive phenotypes, including no abnormal presentation. Nevertheless, the patient should be monitored and assessed through childhood and adulthood for any neuropsychiatric problems.