title: Trisomy 18 mosaicism: report of two cases.
abstract: BACKGROUND
  Mosaic trisomy 18 has a wide phenotypic spectrum ranging from near normal to early death. We report two cases that add to our knowledge of the disease.
  
  
  METHODS
  Patient 1 was a girl with a tracheoesophageal fistula, horse-shoe kidneys and a ventricular septal defect. Karyotyping of her lymphocytes showed complete trisomy 18. Due to her milder phenotypes, skin fibroblasts were karyotyped. Patient 2 was a boy with biventricular hypertrophic cardiomyopathy, patent ductus arteriosus, ventricular and atrial septal defects and significant feeding problems.
  
  
  RESULTS
  Karyotyping of the skin and lymphocytes in patients 1 and 2 respectively revealed trisomy 18 mosaicism. Both children had only mild learning problems and were generally healthy with satisfactory growth. Patient 1 illustrates the possibility of significant discrepancy between the levels of trisomic cells in skin fibroblasts and lymphocytes leading to misdiagnosis. This finding has significant implications in medical management and counselling. Hypertrophic cardiomyopathy in patient 2 is recognized as a novel finding for this condition.
  
  
  CONCLUSIONS
  There is the possibility of good outcome for patients with mosaic trisomy 18, even in the presence of multiple congenital anomalies.
authors: Academic Unit of Medical Genetics, St. Mary's Hospital, Manchester, UK. Siddharth.Banka@manchester.ac.uk
authors: Siddharth
authors: S
authors: Banka
authors: Kay
authors: K
authors: Metcalfe
authors: Jill
authors: J
authors: Clayton-Smith
mesh_terms: D002887:Chromosomes, Human, Pair 18 / Q000235:genetics; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007621:Karyotyping; D008297:Male; D009030:Mosaicism; D010641:Phenotype; D014314:Trisomy / Q000235:genetics*; D000073842:Trisomy 18 Syndrome