Tissue specificity and stability of mosaicism in Pallister-Killian +i(12p) syndrome: relevance for prenatal diagnosis.
We ascertained +i(12p) mosaicism during third trimester in a case of polyhydramnios and diaphragmatic hernia. Primary cultures of amniocytes had colonies with +i(12p), colonies without +i(12p), and mixed colonies with 46/47,+i(12p). The likely explanation was instability and loss of i(12p) during somatic divisions of amniocytes. Fetal blood in third trimester retained +i(12p) in 13% of cells. A review of mosaicism in published cases indicates that factors influencing the presence of +i(12p) include tissue type and in vitro and in vivo age. In blood, amniocyte, and probably bone marrow cultures, +i(12p) is less stable than in fibroblast-like cultures derived from skin and other tissues. Young cultures at early passage are more likely to have +i(12p) than old cultures. Cultures from young (especially fetal) donors are more likely to retain +i(12p) than cultures from adult donors. These rules will be important in determining appropriate tissues for diagnosis and interpretation of mosaicism in this disorder.
Priest
J H
JH
Department of Medical Genetics, Shodair Hospital, Helena, Montana.
Rust
J M
JM
Fernhoff
P M
PM
D000328:Adult; D000653:Amniotic Fluid; D002478:Cells, Cultured; D002869:Chromosome Aberrations / Q000000981:diagnostic imaging / Q000235:genetics*; D025063:Chromosome Disorders; D002881:Chromosomes, Human, Pair 12; D005260:Female; D006801:Humans; D008214:Lymphocytes / Q000378:metabolism / Q000473:pathology*; D009030:Mosaicism; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D013577:Syndrome; D016216:Ultrasonography, Prenatal