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46,XY pure gonadal dysgenesis

Saturday 9 October 2010

Digital cases

- Case 271 : 46,XY Pure gonadal dysgenesis. Streak gonad.

Definition : The 46,XY pure gonadal dysgenesis is more common than the 46,XX pure gonadal dysgenesis.

Etiology

- DHH germline mutations

  • DHH-asssociated gonadal dysgenesis (MIM.233420)

The syndrome of 46,XY pure gonadal dysgenesis may be sporadic or familial with either X-linked recessive or autosomal recessive patterns of inheritance.

Some patients have a 45,X/46,XY mosaicism and are close to mixed gonadal dysgenesis with 45,X/46,XY mosaicism.

The 46,XY pure gonadal dysgenesis may also involve deletion of the SRY gene, a mutated inactive SRY gene or a defective promoter cofactor.

One gene believed crucial for regulating the SRY gene is DAX located on the X chromosomal short arm. The gene is unusual in that only one copy, which is normal, is insufficient to negate the effects of the SRY gene.

A double dosage, i.e., the presence of two active copies in tandem, results in sex reversal from male to female. (It seems that the DAX locus is normally subject to X inactivation as patients with Klinefelter syndrome have two copies of the affected X chromosome locus.)

In one series of 14 XY females with pure gonadal dysgenesis, patients who had normal SRY had gonads composed of undifferentiated stroma in which were tubules or a rete structure suggesting some differentiation towards testis.

In those cases where there were mutations in SRY-orf (SRY-opening reading frames), no tubules were observed; the gonads were composed exclusively of ovarianlike stroma with sclerohyaline nodules in some areas. These data also suggested that SRY may play a role in rete testis formation.

See also

- gonadal dysgenesis

References

- Moltz, L., Schwartz, U., Pickartz, H., Hammerstein, J., Wolf, U. XY gonadal dysgenesis: aberrant testicular differentiation in the presence of H-Y antigen. Obstet. Gynec. 58: 17-25, 1981. [PubMed: 7195530]

- Moreira-Filho, C. A., Frota-Pessoa, O., Vianna-Morgante, A. M., Chu, T. H., Bisi, H., Gollop, T. R. H-Y antigen generating and receptor systems in abnormal sexual development. Am. J. Med. Genet. 13: 401-411, 1982. [PubMed: 7158639]

- Wachtel, S. S., Koo, G. C., de la Chapelle, A., Kallio, H., Heyman, J. M., Miller, O. J. H-Y antigen in 46,XY gonadal dysgenesis. Hum. Genet. 54: 25-30, 1980. [PubMed: 7390478]

- Haseltine, F. P., Ohno, S. Mechanisms of gonadal differentiation. Science 211: 1272-1278, 1981. [PubMed: 7010601]

- Moreira-Filho, C. A., Toledo, S. P. A., Bagnolli, V. R., Frota-Pessoa, O., Bisi, H., Wajntal, A. H-Y antigen in Swyer syndrome and the genetics of XY gonadal dysgenesis. Hum. Genet. 53: 51-56, 1979. [PubMed: 535902]