A novel case of 16q22.3 duplication syndrome in a child with overgrowth: case report and literature review

Abstract

Background: Distal chromosome 16 duplication syndrome (also known as 16q partial trisomy) is a very rare genetic disorder recently described in few clinical reports. 16q trisomy is generally associated with a multisystemic phenotype including intrauterine growth restriction (IUGR), brain and cardiac defects, intellectual disability (ID) and an increased risk of both prenatal and postnatal lethality. Smaller copy number variants (CNV) within the 16q region create partial trisomies, which occur less frequently than full trisomy 16q.

Case presentation: We present the clinical case of a 12-years-old male with a 16q22.3q24.1 de novo heterozygous duplication whose phenotype was characterized by ID, facial dysmorphisms, stature and weight overgrowth. To date, only five other cases of this syndrome have been reported in scientific literature, and none of them comprised overgrowth.

Conclusions: Our case report highlights the great heterogeneity in clinical manifestations and provides new evidence for better defining the phenotypic picture for smaller 16q distal CNVs, suggesting unusual features.

Keywords: 16q22; CNV; Case report; Distal duplication of chromosome 16q; Intellectual disability; Obesity; Overgrowth.

Fig. 1

Photographs of our patient showing dysmorphic facial features, in particular: sparse eyebrows, epicanthus, hypertelorism, midface hypoplasia and thin lips. Absence of 5th finger clinodactyly in both hands

Fig. 2

Cytogenetic analyses results. A: Illumina SNParray showing copy gain in 16q22.3q24.1 by mean of Log R ratio (1) and B-Allele frequency (2). B: image of FISH on metaphases obtained by lymphocyte cultures with the arrow indicating the duplicated chromosomal region

Fig. 3

Chromosome schematic of the duplication in our patient (red box) referenced with the mentioned in the literature (blue boxes) to compare size and location