Abstract for presentation at 11th International Congress of Human Genetics

Prenatal Diagnosis of Pallister-Killian Syndrome

  • Pauline McGrath, Queensland Clinical Genetics Service, Australia
  • Ms Aurelia Citraro, Cytogenetics Division, Department of Pathology, Mater Health Services, Australia
  • Ms Jenny Bryan, Cytogenetics Division, Department of Pathology, Mater Health Services, Australia
  • Dr Kate Gibson, Queensland Clinical Genetics Service, Australia
  • Dr Glenn Gardener, Department of Maternal Fetal Medicine, Mater Mother's Hospital, Australia

    • Pallister-Killian (PK) syndrome or tetrasomy 12p is a rare condition characterised by multiple congenital abnormalities including facial dysmorphism, intellectual disability and seizures, rhizomelic limb shortening, diaphragmatic hernia and fetal overgrowth. Prenatal cytogenetic and sonographic diagnosis remain difficult.PK is a tissue specific syndrome and the percentage of abnormal cells can vary greatly between tissue types and ultrasound anomalies can be inconsistent or absent. We report on two cases of PK diagnosed during pregnancy. In the first case a G1P0 19 year old female presented for tertiary scanning after shortened long bones and 13mm ventriculomegaly were noted on an ultrasound scan at 22 weeks gestation. Amniocentesis was performed and showed a mosaic karyotype 47,XX+i(12)(p10)/46,XX.This pregnancy was terminated at 23 weeks gestation and no post mortem examination occurred.In the second case a G4P1T1MC1 34 year old female presented for chorionic villus sampling after ultrasound findings of an increased nuchal translucency (4.3mm).The maternal age related risk for Down syndrome was adjusted from 1:306 to a risk of 1 in 7.Short term culture results showed a karyotype of 47,XX,+mar in all metaphases examined.The marker was identified by Fluorescent in Situ Hybridisation as consistent with an isochromosome of 12p suggesting Pallister-Killian syndrome.Long term cultures were mosaic with the majority of cells being 46,XX. The 47,XX,+i(12)(p10) cell line was observed in only a very small percentage of metaphases.Subsequent ultrasounds showed a thickened nuchal fold with the only other anomalies being short femur and humerus and reduced crown rump length.Amniocentesis was performed at 15 weeks gestation and confirmed the CVS findings.Cultured and uncultured amniocytes showed a mosaic pattern with varying level of the isochromosome 12p observed.This pregnancy was terminated after 16 weeks gestation and no post mortem examination occurred.

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