Glossary: Definition of Terms:
Ambiguous genitalia : anomalous development of the genitalia resulting in the situation in which the sex of the child cannot be immediately and confidently established.
Androgen Insensitivity Syndrome (AIS) : X-linked disorder associated with undermasculinization of the external genitalia at birth, abnormal sexual development at puberty, and infertility due to defective ability to respond to androgens. In complete forms, the external genitalia appear female and Müllerian structures are absent; over 95% of these individuals have mutations identified in the AR gene, encoding the androgen receptor.
Chimerism : the situation in which an individual arises from two separate embryos that may have different genetic compositions. Compare with mosaicism .
Chromosome-phenotype discordance : the situation in which the chromosomal sex and the phenotypic sex (appearance of the external genitalia) do not match. For example, infants identified as 45,X/46,XY prenatally and born with normal male genitalia, or adolescents with
46,XY karyotype and normal-appearing external female genitalia who have complete androgen insensitivity syndrome.
Congenital adrenal hyperplasia (CAH) : Autosomal recessive disorder characterized by impaired biosynthesis of cortisol from cholesterol in the adrenal cortex. Over 90% are due to defects in the 21-hydroxylase gene, resulting in excessive adrenal androgen biosynthesis and virilization, particularly in females, and salt wasting in many affected individuals that can be lifethreatening.
Disorders of Sex Development (DSD) : New preferred term to encompass a wide range of conditions, including congenital development of ambiguous genitalia, congenital discrepancy between internal and external sex anatomy, incomplete development of sexual anatomy (vaginal agenesis, gonadal agenesis), sex chromosome anomalies, and disorders of gonadal development
(Refs 4-6).
Gender identity : the gender that a person identifies with; i.e., a person’s sense of self as male or female (Ref 30).
Gender role/Gender-role behavior : the predominant sex-specific behavioral characteristics exhibited by a person (Ref 30).
Gonadal dysgenesis : the failure of proper differentiation of a gonad, often resulting in a streak gonad.
Hypogonadotropic hypogonadism : undervirilization of the male genitalia due to inadequate gonadotropin stimulation of the testes, with low serum concentrations of LH and FSH.
* Intersex disorders : any condition with genital ambiguity or chromosome-phenotype discordance. Blackless et al. (Ref 1) use intersex to refer to any deviation from the ideal male or

female with regard to sex chromosome composition, gonadal structure, hormone levels, or internal or external genitalia. Should be avoided because of highly variable usage and definition.
Disorders of sex development (DSD) is now preferred terminology (Refs 4-6).
Mixed gonadal dysgenesis : the presence of a streak gonad and a contralateral testis.
Mosaicism : the presence of two or more populations of cells with different chromosome compositions within a tissue or person. Compare with chimerism .
Müllerian inhibiting substance (MIS; AMH=Anti-Müllerian hormone)
: hormone produced by Sertoli cells of the fetal testes that causes regression of Müllerian structures.
Müllerian structures : internal female genitalia, i.e., uterus and fallopian tubes.
* Pseudohermaphroditism : variably defined in the medical literature. In general, a state in which the external genitalia are ambiguous. “Male pseudohermaphroditism” has been used to describe individuals with an XY chromosomal composition, male gonads, and external genital anomalies. This term is not recommended due to inconsistent usage and negative connotations, and “46,XY DSD” is now recommended (Refs 5,6).
Pure gonadal dysgenesis : the presence of two streak gonads.
* Sex reversal : in general, the phenomenon of the appearance of the genitalia being opposite that of the chromosomal sex; i.e., chromosome-phenotype discordance such as 46,XX male or 46,XY female.
*True hermaphroditism : the presence of both ovarian and testicular tissue in the same person; may be represented by separate testis and ovary or by presence of an ovotestis (or bilateral ovotestes). A histological definition that does not indicate etiology or gonadal karyotype. A new term, “Ovotesticular DSD” has been proposed as a replacement (Refs 5,6).
XX male syndrome : The situation in which an individual with 46,XX chromosome composition has male external genitalia, ranging from normal to ambiguous. In 80% of individuals, the SRY gene, encoding the sex-determining region of the Y chromosome, is present. In the other 20%, the cause is not known. Preferred term is “46,XX testicular DSD” (Refs 5,6).
*Terms to be avoided