Pallister-Killian Syndrome: Undetected by Percutaneous Umbilical Blood Karyotyping and Neonatal Blood Microarray Comparative Genomic Hybridization

Pallister-Killian Syndrome (PKS) is a rare sporadic genetic disorder and tissue-limited characteristics of i(12p) mosaicism. We report a boy who is diagnosed with PKS until the age of 2 years and 3 months. Amniocentesis at 18 weeks of gestation due to advanced maternal age revealed a mosaic supernumerary marker chromosome (47,XY,+mar[30]/46,XY[28]) which was suspected to be an isochromosome 21q. At 21 weeks of gestation, subsequent fetal blood sampling done in another clinic disclosed a normal male karyotype (46,XY). Therefore, the mother chose to continue pregnancy. A conventional chromosome analysis complements the Fluorescence In-Situ Hybridization (FISH) and array Comparative Genomic Hybridization (aCGH) were done from patient’s skin fibroblast culture.The karyotype was confirmed to be mos47,XY,+mar.ish i(12p)[110]/46,XY[11], and array CGH revealed a fourfold increment in 12p. Amniocentesis and conventional chromosomal analysis complements the FISH and array CGH is the optimal method in prenatal diagnosis of PKS. However fetal blood sampling chromosome analysis and peripheral blood array CGH are not recommended because of tissue-limited mosaicism of i(12p) is the characteristic cytogenetic feature of PKS and the extra-chromosome can rarely be identified in blood lymphocyte either prenatally or postnatally.