Chpter 9 Normal and Abnormal Sexual Development

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Chpter 9 Normal and Abnormal Sexual Development
CLINICAL GYNECOLOIC ENDOCRINOLOGY AND INFERTILITY

• OBGY R1 Lee
  Eun Suk

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Normal Sex Differentiation

• Gender identity the result of the following
  determinants
• Genetic sex
• Gonadal sex
• Internal external genitalia
• The secondary sexual characteristics that appear
  at puberty
• The role assigned by society
• Four major steps which constitute normal sexual
  differentiation
• Fertilization and determination of genetic sex
• Formation of organs common to both sexes
• Gonadal differentiation
• Differentiation of the internal ducts and
  external genitalia

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Fertilization and Determination of Genetic Sex

• Step 1 in sex differentiationDetermination of
  genetic sex
• Egg (23,X) Sperm (23,X)46,XX genetic
  female
• OR
• Egg (23,X) Sperm (23, Y)46, XY genetic
  male karyotype

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Formation of Organs Common to Both Sexes

• The fertilized egg multiplies to form a large
  number of cells
• Differentiation of the sex organs in
  this development
• At that stage, both 46,XX 46,XY
  fetuses have similar sex
• organs, specifically
• Gonadal ridges
• Internal ducts
• External genitalia

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Internal reproductive organs
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Gonadal Differentiation

• The important event in gonadal differentiation is
  of the gonadal ridge to become either an ovary or
  a testis
• In males, the gonadal ridge develops into testes
  as a result of a product from a gene located on
  the Y chromosome
• Testis determining factor" (TDF)
• Gonadal medullary resion -gt Sertoli
  cell
• Sex determining region of the Y
  chromosome" (SRY)
• In females, the absence of SRY, due to the
  absence of a Y chromosome, permits the
  expression of other genes
• which will trigger the gonadal ridge to
  develop into ovaries

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Gonadal Differentiation

• Pseudoautosomal region
• The distal ends of the short arms of the X and Y
  chromosomes
• During meiosis the homologous distal short arms
  of the X and Y chromosomes pairs, and interchange
  of genetic material occurs in autosomes
• Gene deletions in this area of the X chromosome
  (Xp22.3) are associated with various conditions
  short stature , mental retardation, X-
  linked ichthyosis, Kallmanns sydrome

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Gonadal Differentiation

• Subsequent sexual differentiation requires
  direction by various genes with TDF
• SRY The Y chromosome sex determinants region
• SOX9 An autosomal testis-determining gene
• DAX1 A potential testis-suppressing gene on
  X-chromosome
• SF1 The link between SRY and the male
  development pathway
• WT1 necessary for normal renal and gonadal
  development
• WNT4 A potential ovary-determining gene on an
  autosome

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Gonadal Differentiation

• SRY
• Sex determining region of the Y chromosome
• Locate on the short arm of the Y chromosome
• Transcription factor contains HMG (high-mobility
  group) box
• - a DNA binding domain gt conrol of
  gene transcrition
• Investigations of the DNA-binding properties of
  the protein of SRY in the promoter P450 aromatase
  (conversion of testosterone to estradiol that is
  down-regulated in the embryo) anti-mullerian
  hormone (responsible for regression of the
  mullerian ducts)
• The expression of SRY in the tissue destined to
  become a gonad directs the cells of this gonadal
  primordium to differentiate as Sertoli cell

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Gonadal Differentiation

• SOX9 An autosomal testis-determining gene
• (SRY-like box) genes are similar
  in sequence to SRY
• an extra copy of SOX9 developes
  males, even if they have no
• SRY gene XX mice made
  transgenic for SOX9 develop testes
• SF1 Steroidogenic factor, necessary to make the
  bipotential gonad
• Collaboration with SOX9 ? elevate
  levels of AMH transcription
• Wnt4 Activate DAX1 expression
• Lack the Wnt4 gene
• ? Ovary fail to form properly,
  express testis specific markers

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Postulated cascades leading to the formation of
the sexual phenotypes
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Summary of key genetic events in early sex
determination

• Migration of primordial germ cells to the
  urogenital ridge
• Differentiation of the bipotential gonadal tissue
  under the direction of WT-1 and SF-1
• SRY activation of male-specific genes,
  especially SOX9, to produce the testes by cell
  proliferation, differentiation, migration and
  vascularization
• Ovarian differentiation by suppression of SOX9
  through the activity of DAX1 and Wnt4

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Summary of the genetics of gonadal dysgenesis

• Gonadal streaks without germ cells in XX or XY
  (female phenotype)
• Deficiencies in WT-1 or SF-1
• Lack of testicular development in XY individuals
• pure gonadal dysgenesis (female phenotype)
  
• Deficiencies in SRY or SOX9
• Male phenotype in a 46,XX individual
• Presence of SRY
• Mixed gonadal dysgenesis in mosaics (varying
  phenotype)
• Excess DAX1

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Internal reproductive organs - Embryonic
development

• Urinary and genital tract
• Closely related, anatomically and embryologically
• Embryologic urinary system -gt important inductive
  influence on developing genital system
• Anomalies in one system are often mirrored by
  anomalies in another system
• Urinary system, internal reproductive organs
  external genitalia
• Develop synchronously at an early embryologic age
  

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Kidney, renal collecting system ureters from
nephrogenic cord
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Mesonephric (Wolffian) duct

• Singular importance for the following reasons
• Grows caudally in developing embryo to open an
  excretory channel into the primitive cloaca and
  outside world
• Serves as starting point for development of the
  metanephros which becomes definitive kidney
• Differentiates into the sexual duct system in
  male
• Although regressing in female fetuses, inductive
  role in development of the paramesonephric or
  mullerian duct

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Mullerian duct

• Paramesonephric or mullerian ducts - development
• Form lateral to mesonephric ducts
• Grow caudally and then medially to fuse in
  midline
• Contact urogenital sinus in region of the post.
  urethra at slight thickening known as sinusal
  tubercle

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Duct System Differentiation - Male

• TDF
• Results in degeneration of gonadal cortex and
  differentiation of the medullary region of the
  gonad into Sertoli cells
• Sertoli cells
• Secrete glycoprotein known as anti-mullerian
  hormone(AMH)
• Regression of paramesonephric duct system in male
  embryo
• Signal for differentiation of Leydig cells from
  the surrounding mesenchyme

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Duct System Differentiation - Female fetus

• In the absence of TDF, medulla regresses and
  cortical sex cords break up into isolated cell
  clusters (-gt primordial follicles)
• In the absence of AMH testosterone
• Mesonephric duct system degenerates
• Then, paramesonephric duct system develops
• Inf. fused portion
• Uterovaginal canal -gt uterus and upper vagina
• Cranial unfused portions
• Open into celomic cavity (future peritoneal
  cavity)
• Fallopian tubes

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Anti-Müllerian Hormone

• A member of the transforming growth factor-ß
  family
• Regression of Müllerian duct system in male
  embryo
• AMH has an inhibitory effect on oocyte meiosis
• Plays a role in the descent of the testes
• Inhibits surfactant accumulation in the lungs
• Proteolytic cleavage of AMH produces fragments
  that have the ability to inhibit growth of
  various tumor ( a potential therapeutic
  application)

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Duct System Differentiation

• Leydig cells
• Produce testosterone dihydrotestosterone with
  5a-reductase
• Testosterone
• Responsible for evolution of mesonephric duct
  system into vas deferens, epididymis, ejaculatory
  duct seminal vesicle
• At puberty, leads to spermatogenesis changes in
  primary and secondary sex characteristics
• DHT(dihydrotestosterone)
• Results in development of the male external
  genitalia , prostate and bulbourethral glands

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External Genitalia Differentiation

• In the female, absence of androgens permits the
  external genitalia to remain feminine
• The genital tubercle becomes the clitoris
• The labioscrotal swellings ? the labia majora
• The urogenital folds ? the labia minora
• In the male, fetal androgens from the testes
  masculinize the external genitalia
• The genital tubercle grows to become the penis
• The labioscrotal swellings fuse to form the
  scrotum

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External Genitalia
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Abnormal Sexual Development

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CLASSIFICATION OF INTERSEXUALITY
Disorders of fetal Endocrinology
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CLASSIFICATION OF INTERSEXUALITY
Primary gonadal defect Swyer syndrome
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How many children are born with intersex
conditions?

• A conservative estimate is that 1 in 2000
  children born will be affected by an intersex
  condition
• 98 of affected babies are due to congenital
  adrenal hyperplasia

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FEMALE PSEUDOHERMAPHRODITISM

• EXCESS FETAL ANDROGENS
• Congenital adrenal hyperplasia
• 21 -hydrxylase deficiency
• 11-hydroxylase deficiency
• 3ß-hydroxysteroid
• dehydrogenase deficiency

• EXCESS MATERNAL ADROGEN
• Maternal androgen secreting tumours (ovary,
  adrenal)
• Maternal ingestion of androgenic drugs

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21-hydrxylase deficiencycongenital adrenal
hyperplasia
Cholesterol
Pituitary
Pregnenolone
ACTH
Progesterone
17-OH progesterone
Adrenal cortex
21-hydroxylase
?? Androgens
Cortisol
Androgens
Cortisol
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Masculinized females CONGENITAL ADRENAL
HYPERPLASIA

• There are several different forms of CAH, each
  related to one of the enzymes necessary to
  transform cholesterol to cortisol
  (hydrocortisone)
• StAR / 20,22-hydroxylase, 3 -hydroxysteroid-dehydr
  ogenase / 17-hydroxylase /
  21-hydroxylase and 11 -hydroxylase
• When one of these enzymes is deficient, this
  leads to a hyperfunction and increased size
  (hyperplasia) of the adrenals
• Among the various forms of CAH, the
  21-hydroxylase deficiency is by far the most
  frequent, representing more than 95 of all cases
• Defect in cortisol biosynthesis, with or without
  aldosterone def, androgen excess

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Masculinized females CONGENITAL ADRENAL
HYPERPLASIA - Biochemistry

• Steroid 21 hyrdoxylase is a cytochrome p-450
  enzyme located in ER
• Catalyzed the conversion of 17-hydoxyprogesterone
  to 11-hydroxycortisol
  precursor of cortisol
• Conversion of progesterone
  
  to deoxycortisterone precursor of aldosterone
  
• This enzyme deficiency -gt adrenal cortex is
  stimulated
• over
  production of cortisol precursor

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Pathways of steroid biosynthesis in the adrenal
cortex
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Hypothalamic pituitary adrenal axis
Renin-angiotensin-aldosterone axis
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Clinical menifestation

• Salt wasting type
• severe form with a concurrent defect in
  aldosterone synthesis
• Simple virilizing type normal aldosterone
  biosynthesis
• Both are together termed classic 21-hydroxylase
  deficiency
• There is also a mild,nonclassic form may be
  asymptomatic
• Classic 21-hydroxylase deficiency 1 in 16,000
  births

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CONGENITAL ADRENAL HYPERPLASIA - salt wasting

• 75 percent of patients with classic
  21-hydroxylase deficiency
• ? severely impaired 21-hydroxylation of
  progesterone
• ? cannot synthesis of aldosterone
• Elevated of 21-hydroxylase precursor aldosterone
  antagonist
• Aldosterone deficiency
• ? hypovolemia and hypereninemia, and
  hyperkalemia (esp. in infant)
• Cortisol deficiency
• ?poor cardiac contractility, poor vascular
  resp. to catecholamine, and
• GFR ? , antidiuretic H ?

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CONGENITAL ADRENAL HYPERPLASIA - salt wasting

• So together hyponatremic dehydration and shock
• Adrenal medulla depending on the glucocorticoid
  in part
• ? so salt wasting 21hyroxylase deficiency
• ? catecholamine deficiency
• ? exacerbating shock Identify e,
  aldosterone, plasma renin
• (hyperkalemia and low aldosterone and
  hyperreninemia)

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Ambiguous genitalia

• Girls with classic 21-hydroxylase deficiency
• exposed to high level of adrenal androgen
  level (GA 7 wks)
• Girls with ambiguous genitalia
• -a large clitoris
• -rugated and partially fused labia
  majora
• -uterus,fallopian tubes, and ovaries
  normal
• Boys
• -no overt signs of the disease
• except variable and subtle
  hyperpigmentation
• and penile en-largement

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Postnatal virilization

• Exposed to the high levels of sex steroids
• Rapid growth (usually androgen effect)
• Advanced bone age ? premature epiphyseal closure
  
  (androgens extragonatal aromatization of
  estrogen)
• Pubic and axillary hair early develop
• Girl clitorial growth
• Young Boys penile growth
• Long term stimulation central precocious puberty

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Linear growth

• A meta-analysis of data from 18 centers showed
• 1.4 SD below the population mean
• Both undertreatment and overtreatment risk for
  short stature
• Undertreatment causing premature epiphyseal
  closure induced
• by high levels of sex
  steroids
• Overtreatment glucocorticoid-induced inhibition
  of the growth

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Reproductive function

• Girls problem at the reproductive system
• -oligomenorrhea, amenorrhea
• -prenatal androgen exposure effect to
  sex-role behavior
• Boys fewer problems

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CONGENITAL ADRENAL HYPERPLASIA - Diagnosis
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CONGENITAL ADRENAL HYPERPLASIA

• Normal infant 100ng/dl (17 hydroxyprogesterone)
• Affected infants10000ng/dl ?
• New born -gt screening test
• 10 (severe affected infant) 17
  hydroxyprogesterone level ?
• Preterm or sick infants -gt 17 hydroxyprogesterone
  level ??
• The severity of hormonal abnormalities depends
  on the type of 21-hydroxylase def
• Salt wasting 17-hydroxyprogesterone
  100000ng/dl

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CONGENITAL ADRENAL HYPERPLASIA

• Random 17-hydroxyprogesterone(17-Ohpro) gt80 ug/L
  or 242 nmol/L (nl lt2.95 ug/L or 9 nmol/L)
• Salt losing gt nonsalt loser
• -gt corticotropin stimulation test unneeded
• Genetic analysis -gt prenatal testing
• Nonclassic CAH random 17-OHpro nl
• -gt Screening
• early morning basal 17-OHpro level
  gt1.5 ug/L (4.5 nmol/L) in children
• gt2.0 ug/L(6nmol/L) in women during
  follicular phase of menstrual cycle
• -gt Corticotropin ST(250ug of
  tetracosactide(cosyntropin) )
• any time during the day gt positive
  17-OHpro gt15.0 ug/L(45nmol/L)

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CONGENITAL ADRENAL HYPERPLASIA

• Heterozygote carrier
• mild elevation, 17-OHpro lt10 ug/L(30nmol/L)
  following CST
• Carrier symptoms or signs of the disease
• Premature adrenarche 1/3 heterozygote carriers
  of 21-OH def (recent)
• 17-OHpro 10-15 ug/L
• -gt DDx of heterozygote carrier or homozygote
  affected Pt
• -gt Genetic analysis

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CONGENITAL ADRENAL HYPERPLASIA Management

• According to the clinical course hormonal level
• Purpose
• normal growth, B.Wt, pubertal development,
  optimal adult height
• Growth velocity, body Wt velocity, bone age
  maturation F/U
• Classic 21-OH def
• -gt glucocorticoid adrenal androgen
  secretion ?
• -gt mineralocorticoid electrolytes plasma
  renin activity normalization

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Treatment Problems

• Hypercortisolism (iatrogenic Cushings syndrome)
  - Sn Sx
• obesity, growth failure, adult short
  stature, striae,
• osteoporosis, hyperlipidemia
• Symptoms of hyperandrogenism
• virilism, infertility of female, precocious
  virilisation of male,
• early puberty, adult short stature

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Glucocorticoid and mineralocorticoid therapy

• Hydrocortisone of physiologic dose
• -gt corticotropin androgen production
  suppression (?) 6 mg/m2/day
• Hydrocortisone 12-15mg/m2/day -gt sufficient
  androgen suppression
• 20 mg/m2/day (neonatal period)
• 25 mg/m2/day -gt do not use
• Dose variability factor
• Indivudual variation in the metabolism and
  sensitivity
• Previous degree of hypothalamic-pituitary-adrenal
  axis suppression
• High dose glucocorticoid short course therapy

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Glucocorticoid and mineralocorticoid therapy

• Mineralocorticoid (fludrocortisone)
• plasma renin activity -gtmid normal range
• Dose 100-200 ug/day
• Nonsalt losing elevated plasam renin activity
• Infant with salt losing NaCl supply -gt1-2
  g/day
• 17mEq Na/NaCl 1g

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CONGENITAL ADRENAL HYPERPLASIA Monitoring
therapy

• Commonly, serum 17-hydroxyprogesterone
  androstenedione level
• Testosterone level in female and prepubertal male
  
• Test time early morning(800 AM)
• Target level of 17-OHpro 4-12 ug/L (12-36
  nmol/L)

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CONGENITAL ADRENAL HYPERPLASIA Prenatal therapy

• Classic CAH fetus pregnant women
• Dexamethasone-gt fetal pituitary adrenal
  axis inhibition
• affected females genital ambiguity?
• Risk mother father - carrier
• -gt classic CAH females 1/8
• Masculinisation of external genitalia
• 6weeks gestation -gt start Tx
• Chorionic villi sampling or amniocentesis
• -gt male or unaffected female -gt Tx stop
• Affected female -gt70 normal birth or sl
  virilization

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Incompletely Masculized Males
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What is AIS?

• A genetic condition where affected people have
  male chromosomes male gonads with complete or
  partial feminization of the external genitals
• An inherited X-linked recessive disease with a
  mutation in the Androgen Receptor (AR) gene
  resulting in
• Functioning Y sex chromosome
• Abnormality on X sex chromosome
• Types
• CAIS (completely insensitive to AR
  gene)-External female genitalia -Lacking female
  internal organs
• PAIS (partially sensitive-varying
  degrees)-External genitalia appearance on a
  spectrum (male to female)
• MAIS (mildly sensitive, rare)-Impaired sperm
  development and/or impaired masculinization
• Also called Testicular Feminization

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Androgen Receptor Gene

• AIS results from mutations in the androgen
  receptor gene, located on the long arm of the X
  chromosome (Xq11-q12)
• The AR gene provides instructions to make the
  protein called androgen receptor, which allows
  cells to respond to androgens, such as
  testosterone, and directs male sexual
  development
• Androgens also regulate hair growth and sex drive
• Mutations include complete or partial gene
  deletions, point mutations and small insertions
  or deletions

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The Process of Sexual Development

• In AIS the chromosome sex and gonad sex do not
  agree with the phenotypic sex
• Phenotypic sex results from secretions of
  hormones from the testicles
• The two main hormones secreted from the testicles
  are testosterone and mullerian duct inhibitor
• Testosterone is converted into dyhydrotestosterone
  
• Mullerian duct inhibitor suppresses the mullerian
  ducts and prevents the development of internal
  female sex organs in males
• Wolffian ducts help develop the rest of the
  internal male reproductive system and suppress
  the Mullerian ducts
• Defective androgen receptors cause the wolffian
  ducts genitals to be unable to respond to the
  androgens testosterone and dihydrotestosterone

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AIS Fetus Development

• Each fetus has non-specific genitalia for the
  first 8 weeks after conception
• When a Y-bearing sperm fertilizes an egg an XY
  embryo is produced and the male reproductive
  system begins to develop
• Normally the testes will develop first and the
  Mullerian ducts will be suppressed and
  testosterone will be produced
• Due to the inefficient AR gene cells do not
  respond to testosterone and female genitalia
  begin to form
• The amount of external feminization depends on
  the severity of the androgen receptor defect
• CAIS complete female external genitalia
• PAIS partial female external genitalia
• MAIS Mild female external genitalia, essentially
  male

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5-alpha reductase deficiency

• Normal internal genitalia
• testes secrete T, MIH causes Mullerian
  ducts to degenerate
• Lack of DHT leads to inadequate masculinization
  of external genitalia at birth
• Testes in labia or inguinal canal
• Urogenital sinus urethra blind vagina
• Prostate gland small or absent
• At puberty, lots of T
• ? testes descend, scrotum darkens, phallus
  enlarges, muscular
• deep voice

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Testing for AIS

• Tests
• During Pregnancy
• Chorionic Villus Sampling (9-12 weeks)
• Ultrasound and Amniocentesis (after 16 weeks)
• After Birth
• Presence of XY Chromosomes
• Buccal Mouth Smear
• Blood Test
• Pelvic Ultrasound
• Histological Examination of Testes

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Treatments

• Surgery
• Orchidectomy or gonadectomy
• Removal of the testes
• Vaginal lengthening
• Genital plastic surgery
• Reconstructive surgery on the female genitalia if
  masculinization occurs
• Phalloplasty
• Vaginoplasty
• Pressure dilation
• Clitorectomy