Constitutional Mosaic Trisomy 13 in Two Germ Cell Layers is Different from Patau Syndrome? A Case Report

Abstract

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.

A Case Study of Mosaic Trisomy 13 in a 2-year-old Filipino Child

“…The review reveals the wide variability of the clinical phenotype and lifespan. 6,[10][11][12][13][14] Two patients had fair to good developmental outcomes. Our patient (10% trisomy 13 in peripheral blood and 25% in array studies) had cognitive performance of 19 months at a chronological age of 24 months.…”

A Six-Year-Old Child With Mosaic Trisomy 13

“…However, non-disjunction of the maternal germ cell leads to 91% of the cases [4]. Mosaic trisomy 13 is reported in 6% of individuals with trisomy 13, and it is characterized by Robertsonian translocation [4][5]. In mosaicism, a combination of both trisomy 13 and euploid cells are present in variable percentages [5].…”

Mosaicismo de trisomía 13

“…La trisomía 13 fue identificada por Patau, et al en 1960 3,6,10,11 . No presenta predominio por sexo y se encuentra en el 1% de los abortos espontáneos (100 veces más que en los nacidos vivos) 3 .…”

“…En los estudios de laboratorio se encontró hipoglucemia, hiperbilirrubinemia (a expensas de la bilirrubina indirecta) e hipocalcemia. El estudio citogenético evidenció 46,XX[34]/47,XX [6] en 40 metafases estudiadas.…”

“…En los sobrevivientes, sin embargo, el retraso mental puede ser de severo a profundo 1,4 . Por su parte, los pacientes con mosaicismo de trisomía 13 presentan expresividad variable 4,6 , desde malformaciones graves y muerte temprana (fenotipo similar a la forma completa) hasta un desarrollo normal y pocos hallazgos dismórficos 2,3 .…”