Clinical, molecular and cytogenetic analysis of 46, XX testicular disorder of sex development with SRY-positive

Abstract

Background: To review the possible mechanisms proposed to explain the etiology of 46, XX sex reversal by investigating the clinical characteristics and their relationships with chromosomal karyotype and the SRY(sex-determining region Y)gene.

Methods: Five untreated 46, XX patients with SRY-positive were referred for infertility. Clinical data were collected, and Karyotype analysis of G-banding in lymphocytes and Fluorescence in situ hybridization (FISH) were performed. Genomic DNA from peripheral blood of the patients using QIAamp DNA Blood Kits was extracted. The three discrete regions, AZFa, AZFb and AZFc, located on the long arm of the Y chromosome, were performed by multiplex PCRs(Polymerase Chain Reaction) amplification. The set of PCR primers for the diagnosis of microdeletion of the AZFa, AZFb and AZFc region included: sY84, sY86, sY127, sY134, sY254, sY255, SRY and ZFX/ZFY.

Results: Our five patients had a lower body height. Physical examination revealed that their testes were small in volume, soft in texture and normal penis. Semen analyses showed azoospermia. All patients had a higher follicle-stimulating hormone(FSH), Luteinizing Hormone(LH) level, lower free testosterone, testosterone level and normal Estradiol, Prolactin level. Karyotype analysis of all patients confirmed 46, XX karyotype, and FISH analysis showed that SRY gene were positive and translocated to Xp. Molecular analysis revealed that the SRY gene were present, and the AZFa, AZFb and AZFc region were absent.

Conclusions: This study adds cases on the five new 46, XX male individuals with SRY-positive and further verifies the view that the presence of SRY gene and the absence of major regions in Y chromosome should lead to the expectance of a completely masculinised phenotype, abnormal hormone levels and infertility.

Figure 1

Fluorescent in situ hybridization (FISH) on metaphase chromosomes of second case with the LSI SRY(orange)/CEP X(green) probes. Metaphase spread showing a normal X chromosome (green signal for centromeric DXZ1 locus) and the SRY (orange) translocates to the distal end of short arm of chromosome X.

Figure 2

Result of multiplex polymerase chain reaction (PCR). Multiplex 1: ZFX/ZFY(690 bp), sY84 (320 bp), sY127 (274 bp); Multiplex 2: SRY (472 bp), sY86 (326 bp); Multiplex 3: sY254 (400 bp), sY134 (301 bp), sY255 (126 bp). M: DL1000 DNAMarker; W: a DNA sample from a woman as a negative control; N: a DNA sample fro-m a normal fertile man as a positive control; P: a DNA sample from the patient; B: a al-ank (water) control.