Complex small supernumerary marker chromosome with a 15q/16p duplication: clinical implications

Abstract

BackgroundComplex small supernumerary marker chromosomes (sSMCs) consist of chromosomal material derived from more than one chromosome and have been implicated in reproductive problems such as recurrent pregnancy loss. They may also be associated with congenital abnormalities in the offspring of carriers. Due to its genomic architecture, chromosome 15 is frequently associated with rearrangements and the formation of sSMCs. Recently, several different CNVs have been described at 16p11.2, suggesting that this region is prone to rearrangements.ResultsWe detected the concomitant occurrence of partial trisomy 15q and 16p, due to a complex sSMC, in a 6-year-old girl with clinical phenotypic. The karyotype was analyzed by G and C banding, NOR staining, FISH and SNP array and defined as 47,XX,+der(15)t(15;16)(q13;p13.2)mat. The array assay revealed an unexpected complex sSMC containing material from chromosomes 15 and 16, due to an inherited maternal translocation (passed along over several generations). The patient’s phenotype included microsomia, intellectual disability, speech delay, hearing impairment, dysphagia and other minor alterations.DiscussionThis is the first report on the concomitant occurrence of partial trisomy 15q and 16p. The wide range of phenotypes associated with complex sSMCs represents a challenge for genotype-phenotype correlation studies, accurate clinical assessment of patients and genetic counseling.

Distal Partial Trisomy 15q26 and Partial Monosomy 16p13.3 in a 36-Year-Old Male with Clinical Features of Both Chromosomal Abnormalities

“…The break-points for the duplication of 15q may vary, but the general phenotype remains similar, including pre- and post-natal overgrowth and mild to profound intellectual disability [Jones, 2006; Su et al, 2010; Chen et al, 2011], downslanting palpebral fissures and elongated face, a broad nasal bridge and long philtrum, a high-arched palate, micrognathia, joint defects with slender fingers/toes, and hypotonia [Christofolini et al, 2014]. Tall stature and long fingers have also been reported in individuals with tetrasomy 15q [Blennow et al, 1994; Rowe et al, 2000].…”

Investigação clínica e citogenética molecular em pacientes com atraso de desenvolvimento neuropsicomotor associado à malformação congênita

“…Da mesma forma, o estudo completo de uma família portadora de um desequilíbrio genômico transgeracional, foi possível graças a uma estratégia combinada, utilizando técnicas de citogenética clássica e molecular (Christofolini et al, 2014).…”