TY  - JOUR
AU  - Bisba, Maria
AU  - Louizou, Eirini
AU  - Tzanakis, Konstantinos
AU  - Liehr, Thomas
AU  - Vittas, Spiros
PY  - 2026
DA  - 2026/08/21
TI  - Prenatal Diagnosis of a Low-Level Mosaic Small Supernumerary Marker Chromosome (sSMC): Early Postnatal Clinical Follow-Up
JO  - OBM Genetics
SP  - 353
VL  - 10
IS  - 03
AB  - Small supernumerary marker chromosomes (sSMCs) are rare chromosomal abnormalities with diverse outcomes and variable effects that can be detected prenatally. The clinical significance of low-level mosaic sSMCs is often uncertain, and postnatal follow-up is essential to assess phenotypic outcomes. A fetus in whom a low-level mosaic sSMC (8%) was detected during prenatal testing is reported. The sSMC was found in 12 out of 150 metaphases examined by conventional karyotype, followed by molecular cytogenetic analyses (chromosomal microarray analysis (CMA) and fluorescence in situ hybridization (FISH)). Detailed ultrasound examination during the whole pregnancy revealed no structural abnormalities or other fetal complications and the child was born at term. Postnatal clinical investigation was conducted to evaluate the phenotypic impact of the sSMC and demonstrated normal early growth and neurodevelopment during the first nine months of life. Prenatal testing revealed a de novo sSMC in a low-level mosaic state. Evaluation of the sSMC revealed that the origin is in the pericentromeric region of chromosome 8, consisting predominantly of heterochromatic but also of euchromatic material. Integrating prenatal detection, molecular characterization, and postnatal clinical evaluation is crucial for managing cases with low-level prenatal mosaic sSMCs. Comprehensive follow-up is essential for better prognostic counseling and management in affected children.
SN  - 2577-5790
UR  - https://doi.org/10.21926/obm.genet.2603353
DO  - 10.21926/obm.genet.2603353
ID  - Bisba2026
ER  -