Mosaic Trisomy 14 with Severe Short Stature: A Case Report

Mosaic trisomy 14 is a rare chromosomal anomaly with a broad phenotypic spectrum. We report a 10-year-3-month-old girl with severe short stature, developmental delay, and repaired patent ductus arteriosus. An incompletely documented combined insulin–clonidine stimulation test yielded a peak GH concentration of 6.85 ng/mL and was not considered sufficient to establish growth hormone deficiency. Karyotyping of 100 peripheral-blood metaphases showed 47,XX,+14[6]/46,XX[94]. Initial copy-number sequencing detected a 34.37 Mb mosaic 14q gain; repeat SNP-based chromosomal microarray analysis demonstrated an approximately 86.83 Mb 14q11.2-q32.33 mosaic gain at an array-estimated fraction of approximately 50%, compatible with the cytogenetic diagnosis. Targeted 14q32.2 analysis showed increased total and methylated-allele dosage, with methylated fractions of 48.6–62.3%, interpreted as dosage imbalance within the broader 14q gain rather than an independent epimutation. Four STR loci showed biparental inheritance. Quantitative peak-height and peak-area analysis at three informative, bias-correctable STR loci demonstrated excess paternal-allele dosage, providing independent support for, but not definitive proof of, paternal origin of the additional chromosome 14. rhGH was prescribed for SGA with persistent short stature at 0.22 mg/kg/week. At three months, height was 124.7 cm (+1.9 cm); no adverse events were reported. These observations do not establish treatment efficacy or safety.