Small supernumerary marker chromosome originating from chromosome 10 associated with an apparently normal phenotype

Abstract

Small supernumerary marker chromosomes (sSMC) originating from chromosome 10 are rare. Only seven cases have been documented, and among those three cases were diagnosed prenatally. We reported on another prenatal diagnosis of a de novo mosaic sSMC in an apparently normal female fetus whose mother had conceived with assisted reproductive technology (ART) procedures. G-banding analysis of amniotic cells was performed. Spectral karyotyping (SKY) and fluorescence in situ hybridization (FISH) studies with chromosome 10-specific alphoid satellite DNA probe were used to identify the chromosome 10 origin of the sSMC. Further FISH study with telomeric sequence probes showed that the sSMC lacked a hybridization signal, suggesting that the marker could be a ring chromosome. FISH studies using BAC clone probes specific for the regions within 10p11.2, 10q11.1, and 10q11.2 showed that the short arm breakpoint was located between 29.8 and 30.7 Mb from the 10p telomere, and that the long arm breakpoint was located less than 43.6 Mb from the 10p telomere. The karyotype of the fetus was 47,XX,+mar. ish der(10)(SKY+ CEP 10+, CTD-2130I7+, RP11-89J23-)/46,XX. Oligonucleotide microarray-based copy number variations (CNV) analysis was also performed and showed a 6.7 Mb duplication from 10p11.2 to 10q11.2 (36.2-42.9 Mb) with Affymetrix SNP-array 6.0 genotype: arr cgh. 10p11.2q11.2(CN_519687 --> CN_541524) X 3. At the 1-year follow-up, the baby did not have any findings of the trisomy 10p syndrome. This observation provided further credence to the concept that additional chromosome material of proximal 10p11.2 may not contribute to the trisomy 10p syndrome phenotype.

Molecular characterization of 39 de novosSMC: contribution to prognosis and genetic counselling, a prospective study

“…Array-CGH and SNP array are powerful tools for delineating chromosomal imbalances. However, there have been no large series reporting the application of this technology to sSMC in a postnatal (14)(15)(16)(17)(18)(19)(20)(21)(22) or prenatal context (23)(24)(25)(26)(27)(28)(29), or both (30,31). Genotype-phenotype correlations should be extended, and SNP array also offers the possibility to detect uniparental disomy (UPD), in particular, for sSMC derived from chromosome 6, 7, 11 and 20 (32,33).…”

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

“…Only one apparently non-mosaic case of sSMC(10) was described in a phenotypically normal fetus but without postnatal follow-up. In this case the trisomic region ranged from 36.19 to 42.99 Mb (UCSC hg19, 2009) [Sung et al, 2009].…”

An Improved Method to Extract DNA from 1 ml of Uncultured Amniotic Fluid from Patients at Less than 16 Weeks’ Gestation

“…Larrabee et al [1] were the first to test the array-CGH technique to analyze fetal DNA extracted from AF cffDNA and to compare the results obtained by array-CGH with those obtained with conventional karyotyping. In the literature, in a prenatal context, array-CGH analysis of cultured AF has been applied to marker or apparently balanced translocations, and has allowed genetic counseling [27], [28].…”