Pallister-Killian syndrome (PKS) is a dysmorphic condition involving most organ systems, but is also characterized by a tissue-limited mosaicism; most fibroblasts have 47 chromosomes with an extra small metacentric chromosome, whereas the karyotype of lymphocytes is normal. The extra metacentric chromosome is an isochromosome for part of the short arm of chromosome 12: i(12)(p10) (Peltomaki et al., 1987; Warburton et al., 1987).

Mayer-Rokitansky-Kuster-Hauser syndrome (MRKH) is characterized by uterovaginal atresia in an otherwise phenotypically normal female with a normal 46,XX karyotype. Anomalies of the genital tract range from upper vaginal atresia to total mullerian agenesis with urinary tract abnormalities. It has an incidence of approximately 1 in 5,000 newborn girls (Cheroki et al., 2006). The abnormality of sexual development in MRKH syndrome is the same as that in the MURCS association (601076), in which cervicothoracic somite anomalies, unilateral renal agenesis, and conductive deafness are also seen. Mullerian aplasia and hyperandrogenism (158330) is caused by mutation in the WNT4 gene (603490). Familial cases of unilateral or bilateral renal agenesis in combination with mullerian anomalies have also been reported (see urogenital adysplasia, 191830).