Mixed gonadal dysgenesis
Encyclopedia
Mixed gonadal dysgenesis is a condition of unusual and asymmetrical gonadal development leading to an unassigned sex differentiation. A number of differences have been reported in the karyotype
, most commonly a mosaicism 45,X/ 46, XY. If Turner syndrome
is defined as a condition where one sex chromosome is absent or abnormal, mixed gonadal dysgenesis may be interpreted as a specific variation of Turner’s. The phenotypical expression may be ambiguous, intersex
, or male, or female pending the extent of the mosaicism.
It has been pointed out that the gonads may not be symmetrical, thus the development of the Müllerian duct
and Wolffian duct
may be asymmetrical, too. Because of the presence of dysgenetic gonadal tissue and Y chromosome material, there is a high risk of the development of a gonadoblastoma
, thus removal of the gonads is usually indicated.
Although similar in some ways to true hermaphroditism
, the conditions can be distinguished histologically.
Karyotype
A karyotype is the number and appearance of chromosomes in the nucleus of an eukaryotic cell. The term is also used for the complete set of chromosomes in a species, or an individual organism.p28...
, most commonly a mosaicism 45,X/ 46, XY. If Turner syndrome
Turner syndrome
Turner syndrome or Ullrich-Turner syndrome encompasses several conditions in human females, of which monosomy X is most common. It is a chromosomal abnormality in which all or part of one of the sex chromosomes is absent...
is defined as a condition where one sex chromosome is absent or abnormal, mixed gonadal dysgenesis may be interpreted as a specific variation of Turner’s. The phenotypical expression may be ambiguous, intersex
Intersex
Intersex, in humans and other animals, is the presence of intermediate or atypical combinations of physical features that usually distinguish female from male...
, or male, or female pending the extent of the mosaicism.
It has been pointed out that the gonads may not be symmetrical, thus the development of the Müllerian duct
Müllerian duct
Müllerian ducts are paired ducts of the embryo that run down the lateral sides of the urogenital ridge and terminate at the Müllerian eminence in the primitive urogenital sinus. In the female, they will develop to form the Fallopian tubes, uterus, cervix, and the upper two-third of the vagina; in...
and Wolffian duct
Wolffian duct
The mesonephric duct is a paired organ found in mammals including humans during embryogenesis....
may be asymmetrical, too. Because of the presence of dysgenetic gonadal tissue and Y chromosome material, there is a high risk of the development of a gonadoblastoma
Gonadoblastoma
A gonadoblastoma is a complex neoplasm composed of a mixture of gonadal elements, such as large primordial germ cells, immature Sertoli cells or granulosa cells of the sex cord, and gonadal stromal cells.-Associations:...
, thus removal of the gonads is usually indicated.
Although similar in some ways to true hermaphroditism
True hermaphroditism
True hermaphroditism is a medical term for an intersex condition in which an individual is born with ovarian and testicular tissue.There may be an ovary on one side and a testis on the other, but more commonly one or both gonads is an ovotestis containing both types of tissue.It is rare—so...
, the conditions can be distinguished histologically.