| Sex development in human is determined by lots of genes on sex chromosomes and autosome. It can be divided into two stages: sex determination and sex differentiation. If Y chromosome is present, the gonad developed into testes. Aberration of Y chromosome can result in different disorders, such as gonadal dysgenesis, hermaphrodites and other abnormalities. Isodicentric chromosomes are the most commonlt reported Y chromosome aberrations. Most reported patients with isodicentric Y are chromosomal mosaics. The resulting phenotype varies due to the structure of the abnormal Y and the proportion of each cell line and vary from male to individual with ambiguous or abnormal female. Sex-determining region Y (SRY) is the key gene that initiates male sex development. X chromosome inactivation is the epigenetic mechanism for female cells (XX) to achieve gene dosage compensation with male (XY). The X structural imbalances in females may lead to duplication of X chromosome, which result in variable phenotype.3 patients with ambiguous genitalia were reported. The karyotype and molecular features of patients were determined by G-banding, DAPI-banding, fluorescence in situ hybridization and molecular analysis. Case 1 is a 2-month old infant with hypospadias, cryptorchidism. Small uterus presence was showed by CT. The karyotype is 45,X(40%)/46,X,idic(Y)(p11.3)(58%)/47,XY,idic(Y)(p11.3)(2%) mosaic. PCR amplification of SRY and AZF genes is positive. Case 2 is a 19 years old female with short statue and amenorrhea. A few of primordial follicles were found in ovaries. The karyotype is 45,X(75%)/46,X,dic(Y)(p11.3)(25%), the SRY gene of the patient is normal. Patient 3 is a 15 years old female with amenorrhea, the secondary sexual characteristics were underdeveloped. A small uterus and ovaries were showed by CT. Her karyotype is 46,X,t(3;6)(3p14;6p23);t(X;9)(q21;p23). Mechanisms of the sex chromosome aberration causing abnomal sex development were discussed. |
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