1. Disorders of Sexual Differentiation
A Amirhakimi, MD Pediatric Endocrinologist
Shiraz University of Medical Sciences

2. Development of Reproductive Systems
Begins at 4 to 5 weeks’ gestation
May be considered complete with the development of secondary sexual characteristics and fertility (i.e., production of viable gametes) after puberty

3. Sex Determination and Sex Differentiation
Sex determination: the bipotential gonad develops into a testis or an ovary.
Sex differentiation: the developing gonad functions appropriately to produce peptide hormones and steroids.

4. Determination
Differentiation

5. Sex Development Three major components:
Chromosomal sex: the karyotype (46,XX, 46,XY, or variants).
Gonadal sex: the presence of a testis or ovary after the process of sex determination.
Phenotypic (anatomic) sex: the appearance of the external genitalia and internal structures after the process of sex differentiation.
Psychosexual development (“brain sex”): an unpredictable outcome of several biologic factors, as well as environmental and social influences.

6. Chromosomal Sex Determined at the time of fertilization
A single Y chromosome:
usually is sufficient to drive testis development, even in the presence of multiple copies of chromosome X.
Contains 2% of the DNA genome
X chromosome:
Contains 5% of the DNA genome

7. Gonadal Sex
The bipotential gonad remains indifferent until 42 d (6wks)
The internal & external genitalia are formed between 9 &13 wks of gestation.

8. Phenotypic or Anatomic Sex

9. Male Sexual Differentiation (a more active developmental process)
Regression of Müllerian structures (uterus, fallopian tubes, and the upper one third of the vagina)
Stabilization of Wolffian structures (seminal vesicles, vasa deferentia, and epididymides)
Androgenization of the external genitalia (penis and scrotum)
Descent of the testes from their origin in the urogenital ridge to their final position in the scrotum

10. Male Sexual Differentiation
Sertoli Cells → AMH (7th wk) → Regression of mullerian structures (9-12th wk)
Fetal Leydig Cells and Steroidogenesis
Androgen production (8-9th wk, LH & hCG independent)
LH/hCG receptor (10-12th wk):
first 2 trimesters: hCG
after 20th wk: LH
Massive leydig cell expansion (14-18th wk) → marked testosterone secretion (16th wk)

11. Male Sexual Differentiation
Local production of testosterone → stabilization of Wolffian structures
DHT → androgenization of the external genitalia and urogenital sinus
urogenital sinus → prostate and prostatic urethra
genital tubercle → glans penis
urogenital (urethral) folds → shaft of the penis
urogenital (labioscrotal) swellings → scrotum
Testis Descent (from 8th wk to mid 3rd trimester)
Transabdominal stage (8-15th wk)
Transinguinal (inguinoscrotal) stage (25-35th wk)
Subsequent Testicular Development (2nd & 3rd trimester)

12. Female Sexual Differentiation
Ovary is steroidogenically quiescent until the time of puberty (estrogen synthesis → breast and uterine development and follicular development → regular menstrual cycles)
Specific complement of genes are implicated in ovarian development and integrity, some of which may actively antagonize testis differentiation.

13. Female Sexual Differentiation
Mullerian structures persist
Uterine development
Lack of local testosterone → Wolffian degeneration
External Genitalia:
urogenital sinus → urethra and lower portion of the vagina
genital tubercle → clitoris
urogenital (urethral) folds → labia minora
urogenital (labioscrotal) swellings → labia majora

14. Normal Sexual DevelopmentXY
Testes
AMH Testosterone
Mullerian Testicular Wolffian DHT
Regression Descent Stabilization
Development of Male External Genitalia

16. Psychosexual Development
Gender identity: a person's self-representation or identification as male or female (established at m/o)
Gender role (sex-typical behaviors): expression of psychological characteristics that are sexually dimorphic within the general population (toy preferences, physical aggression, …)
Sexual orientation: choice of sexual partner (e.g., heterosexual, bisexual, homosexual)

18. Case 1 The most likely diagnosis? Further work ups?
A 15y/o girl with short stature and primary amenorrhea.
Hx of recurrent ear infections, has quit school
Physical exam: ht:142cm, webbed neck, low hair line, abnormal nails
Lab data: FBS: 140mg/dl, increased FSH & LH, low estradiol
The most likely diagnosis?
Further work ups?

19. Case 2 Most likely diagnosis and the most important work up?
A 15y/o girl with primary amenorrhea.
Hx of inguinal hernia repair in infancy, episodes of weakness and paralysis.
Physical exam: BP:160/100, Ht: 170cm, breast stage: I.
Lab: K:2.5, Testosterone: low, FSH & LH: high, bone age: 11y/o
Most likely diagnosis and the most important work up?

20. DSDs (Disorders of Sexual Differentiation)
Defined as “congenital conditions in which development of chromosomal, gonadal, or anatomic sex is atypical”
The most common cause of ambiguous genitalia of the newborn, CAH, is classified as 46,XX DSD
The next most common cause, PAIS, is classified as 46,XY DSD

21. Revised Nomenclature DSDs = Intersex 46,XY DSD = 46,XX DSD =
Male pseudohermaphrodite
Undervirilization of an XY male
Undermasculinization of an XY male
46,XX DSD =
Female pseudohermaphrodite
Overvirilization of an XX female
Masculinization of an XX female
True hermaphrodite = Ovotesticular DSD
XX male or XX sex reversal = 46,XX testicular DSD
XY sex reversal = 46,XY complete gonadal dysgenesis

22. Ambigous Genitalia Ambigous genitalia at birth: 1/4000
Sex assignment is based on the birth phenotype, simultaneously accompanied by gender assignment and sex of rearing as male or female.
Reaching a final decision may be delayed by the nature and complexity of the investigations and assessments required.

23. Virilization of the 46XX Female (46XX DSD)
Presence of excessive androgens during wks of gestation
Magnitude of changes: mild clitoral enlargement → male phallus with a penile urethra and fused scrotum with raphe
Isolated clitoromegaly occurs from later androgen exposure.

24. Causes of Virilization in the Female
Additional Features
Condition
Salt loss in some
21-Hydroxylase Deficiency
Salt loss
3β-Hydroxysteroid Dehydrogenase Deficiency
Salt retention/ HTN
11β-Hydroxylase Deficiency
Between 9 & 12 wks of gestation
Androgenic Drug Exposure
Karyotype: 46XY/ 45X
Mixed Gonadal Dysgenesis
Testicular and ovarian tissue present
True Hermaphrodite
Rare, Positive history
Maternal Virilizing Adrenal or Ovarian Tumor

25. Inadequate Masculinization of the 46XY Male (46XY DSD)
Small penis + variable degrees of hypospadias & associated chordee or ventral binding of the phallus + unilateral or bilateral cryptorchidism
Microphallus without ambigous genitalia as a result of congenital gonadotropin deficiency is often combined with GH & ACTH deficiencies (neonatal hypoglycemia).

26. Causes of Inadequate Masculinization of the Male
Condition
Additional Features
StAR Deficiency
Salt loss
3β-Hydroxysteroid Dehydrogenase Deficiency
17-Hydroxylase Deficiency
Salt retention/ hypokalemia/HTN
17-Hydroxysteroid Oxidoreductase Deficiency
Adrenal function: normal
Dysgenetic Testes
Possible abnormal karyotype
Leydig Cell Hypoplasia
Rare
CAIS or Testicular Feminization
Female external genitalia, absence of mullerian structures
PAIS
As above with ambigous external genitalia
5α-Reductase Deficiency
Autosomal recessive, virilization at puberty

27. Approach to the Infant with Genital Ambiguity
Rapid identification of any life-threatening condition (CAH).
Prenatal androgen exposure causes a tendency toward a male gender identity & male gender role.
Feasibility of genital reconstruction & potential fertility are more important.
Extensive open discussion with parents.
Individualized treatment by a team of experts.

28. Diagnosis Inguinal gonads:
Testes
Ovaries
Ovotestes
Absent female internal genitalia: presence of AMH secreted by fetal testes
Karyotype
Most virilized females → CAH( 21-hydroxylase def) → 17-hydroxyprogestrone & androstendione
Diagnosis is more difficult in undervirilized males.
Abnormalities of sex chromosomes may be associated with dysgenetic gonads or persistent mullerian structures.

29. Treatment Hormone replacement
Steroids in CAH
Testosterone
Surgical reconstruction(by 2 y/o / ?later)
Psychological support (whole family)
Removal of discordant gonad or internal organs
Risk of gonadoblastoma or dysgerminoma in dysgenetic gonads with Y-genetic material.
Possibility of later change of gender