The cytogenetic analyses revealed a 45,X non mosaic karyotype in 50%, isochromosomes in 25%, proximal long or short arm deletions in 7.5%, markers in 7.5%, mos 45,X/ 46XY in 5% and other karyotypes in 5% of the patients (Table 1). The SRY gene was detected only in two patients who had the mos 45,X/46XY karyotype, whereas all other patients were SRY negative (Table 1). The presence of an endometrial adenocarcinoma in a 21-year-old patient with 45,X karyotype and a negative SRY gene in both peripheral blood leucocytes and an ovarian sample raised high suspicions of unidentified Y chromosome sequences. However, a search for three additional loci in the AZF region on Yq (AZFb, AZFa and AZFc) was negative, thereby excluding the possibility of an unidentified Y chromosomal mosaicism (data not shown).

  We found an incidence of SRY-gene-positive results of 5% in Turner syndrome patients (Table 1). Figure 2 shows electrophoresis of PCR amplification products of a 270 bp SRY-gene-specific fragment using primers SRY 1F/SRY 2R. Figure 3 shows electrophoresis of PCR amplification products of a 609 bp SRY-gene-specific fragment using primers XES7/XES2.