The heterogeneous phenotype of known syndromes is a clinical challenge, and 
harmonized description using globally accepted ontology is desirable. This 
report attempts phenotypic analysis in a patient of constitutional mosaic 
trisomy 13 in mesoderm and ectoderm to make globally comparable clinical 
description. Phenotypic features (minor/major abnormalities) were recorded and 
matched with the Human Phenotype Ontology terms that were used to query 
web-based tool Phenomizer. We report here a case of 24-year-old girl born to non 
consanguineous parents with history of one abortion. Her phenotypic evaluation 
included short columella, low-set ears, seizures, enlarged naris, bifid tongue, 
infra-orbital fold, smooth philtrum, microtia, microcephaly, carious teeth, 
downslanted palpebral fissures, proportionate short stature, high palate, thin 
upper lip vermilion, small for gestational age, broad fingertip, broad hallux, 
mandibular prognathia and dental malocclusion. Karyotype and interphase FISH 
(Fluorescence in situ hybridization) was done in blood cells. Interphase FISH 
was also performed on buccal epithelial cells. Cytogenetic analysis demonstrated 
trisomy 13 mosaicism in 25% cells i.e. 47, XX,+13(9)/46,XX(27). The interphase 
FISH in blood cells showed trisomy 13 in 15%, whereas in buccal mucosa cells 
showed nearly 6%. Mosaic aneuploidy in constitutional karyotype can be 
responsible for variation in clinical and morphological presentation of patient 
with genetic disorder.