Three-Year Follow-Up of a Prenatally Ascertained Apparently Non-Mosaic sSMC(10): Delineation of a Non-Critical Region

Abstract

Small supernumerary marker chromosomes (sSMC) originating from chromosome 10 are rare and usually found in mosaic form. We present a de novo apparently non-mosaic sSMC(10) prenatally diagnosed in amniotic fluid and postnatally confirmed in peripheral blood. Characterization by array-CGH showed a pericentromeric duplication of 7.1 Mb of chromosome 10. The fetus did not show ultrasound abnormalities, and a normal female phenotype was observed during a 3-year postnatal follow-up. The absence of phenotypic abnormalities in the present case provides evidence of a non-critical pericentromeric region in 10p11.21q11.1 (hg19 35,355,570-42,448,569) associated with a duplication.

Prenatal diagnosis and genetic counseling of a 10p11.23q11.21 duplication associated with normal phenotype

“…According to the literature [ 1 , 8 – 12 ] yet only several cases/ families with partial trisomies of chromosome 10 within the pericentromeric region are reported, which did not show any or minimal clinical signs. Different from trisomy 10p syndrome, the pericentromeric region of chromosome 10 is proposed [ 11 ] to be a triplo-insensitive pericentromeric region.…”

“…Predicting the phenotypic outcome of prenatally diagnosed de novo partial dup(10) remains challenging. Important efforts have been devoted to define chromosome non-critical pericentromeric regions that tolerate duplication without phenotypic effects, a key issue in genetic counseling [ 8 ]. Unfortunately, most defined non-critical regions remain speculative at present, because available information is scarce.…”