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Reproductive Physiology, Endocrinology, and Infertility

Question
40 out of 56
 

A 17 yr-old-girl with presented with amenorrhoea, absent breasts, and small hypoplastic uterus. Which of the following would be the most likely diagnosis? (AIPG 2011)



A Turner’s Syndrome
B Kallman’s syndrome

C Gonadal dysgenesis
D Shehan’s syndrome

Ans. C

Gonadal dysgenesis

1. Pure Gonadal Dysgenesis

a. Pure gonadal dysgenesis refers to phenotypically female individuals who have sexual infantilism, primary amenorrhea with normal stature, and no chromosomal abnormalities (46,XX or 46,XY).

b. The gonads are usually streaks, but there may be some development of secondary sexual characteristics as well as a few episodes of uterine bleeding.

c. Mutations in the SRY (sex-determining region gene on the Y chromosome) have been identified in some XY females with gonadal dysgenesis.

2. Mixed Gonadal Dysgenesis (45, X/46, Xy)

a. Mixed gonadal dysgenesis typically results from 45,X/46,XY mosa- icism.

b. The phenotype of patients with this condition varies consider- ably.

c. Although some patients have a predominantly female phenotype with somatic features of TS, streak gonads, and müllerian structures, most 45,X/46,XY individuals have a male phenotype and testes, and the diagnosis is made incidentally after amniocentesis or during investigation of infertility.

d. In practice, most children referred for assessment

e. have ambiguous genitalia and variable somatic features.

f. A female sex- of-rearing is often chosen (60%) if phallic development is poor and uterine structures are present.

g. However, gonadectomy is indicated to prevent further androgen secretion and to prevent development of gonadoblastoma (up to 25%). Individuals raised as males may require reconstructive surgery for hypospadias and removal of dysgenetic gonads.

h. Scrotal testes can be preserved but need regular examination for tumor development.

i. Biopsy for carcinoma in situ is recommended in adolescence, and testosterone supplementation may be required for vi- rilization in puberty. Height potential is usually limited.

3. Kallmann Syndrome

a. This syndrome results from defective hypothalamic gonadotropin-releasing hormone (GnRH) synthesis and is associated with anosmia or hyposmia due to olfactory bulb agenesis or hypoplasia.

b. The syndrome may also be associated with color blindness, optic atrophy, nerve deafness, cleft palate, renal abnormalities, cryptorchidism, and neurologic abnormalities such as mirror movements.

c. Defects in the KAL gene, which maps to chromosome Xp22.3, prevent embryonic migration of GnRH neurons from the hypothalamic olfactory placode to the hypothalamus.

d. Genetic abnormalities, in addition to KAL mutations, can also cause isolated GnRH deficiency, as autosomal recessive (i.e., GPR54) and dominant (i.e., FGFR1) modes of transmission have been described.

e. GnRH deficiency prevents progression through puberty.

f. Males present with delayed puberty and pronounced hypogonadal features, including micropenis, probably the result of low testosterone levels during infancy.

g. Female patients present with primary amenorrhea and failure of secondary sexual development.

h. Kallmann syndrome and other causes of congenital GnRH deficiency are characterized by low LH and FSH levels and low concentrations of sex steroids (testosterone or estradiol).

i. In sporadic cases of isolated gonadotropin deficiency, the diagnosis is often one of exclusion after eliminating other causes of hypothalamic-pituitary dysfunction.

j. Re- petitive GnRH administration restores normal pituitary gonadotropin responses, pointing to a hypothalamic defect.

k. Long-term treatment of men with human chorionic gonadotropin (hCG) or testosterone restores pubertal development and secondary sex characteristics; women can be treated with cyclic estrogen and progestin.

l. Fertility may also be restored by the administration of gonadotropins or by using a portable infusion pump to deliver subcutaneous, pulsatile GnRH.

a. In Mayer- Rokitansky-Kuster-Hauster syndrome congenital absence of the uterus is usually associated with absent vaginA.

b. Presents with primary amenorrhoea, 46 XX karyotype and normal ovarian function and secondary sexual development. Differential diagnosis - androgen insensitivity syndrome.

4. Kallmann’s syndrome is an X-linked disorder characterized by hypogonadotropic hypogonadism, which is associated with anosmiA. This disorder more commonly affects men than women.

5. The McCune-Albright syndrome is characterized by patchy cutaneous hyperpigmentation, polyostotic fibrous dysplasia, and several endocrine disorders including toxic multinodular goiter.

6.

a. Testicular feminization syndrome, now more appropriately called the complete androgen insensitivity syndrome, is a genetic disorder that makes XY fetuses insensitive to androgens (male hormones).

b. Instead, they are born looking externally like normal girls. Internally, there is a short blind-pouch vagina and no uterus, fallopian tubes or ovaries. There are testes in the abdomen or the inguinal canal.

Reproductive Physiology, Endocrinology, and Infertility Flashcard List

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