Background: Pallister-Killian syndrome is a rare sporadic genetic disorder with a tissue-specific mosaic distribution of an additional isochromosome 12p [i(12p)]. Due to the low risk of recurrence, prenatal diagnosis of this syndrome is important for the genetic counseling.
Objective: To report the first prenatal diagnosis case of Pallister-Killian syndrome in Mexico (lethal neonatal presentation associated with hypoplastic left heart).
Methods/results: We admitted to our hospital a third-trimester, 31-year-old-pregnant woman; the level II sonographic examination showed: polyhydramnios, micromelia, hypoplastic left heart and a fetal facial profile characterized by small nose, thin upper lip and protruding lower lip. We confirmed the diagnosis with cultured amniotic cells. Standard G banding techniques showed a male karyotype with an extra chromosome i(12p) in the 100% of metaphase cells: 47,XY, + i(12p).