DSDs-Turners, Klinefelters

Question 1

Turners- genotype/origin

Answer 1

X-“null”

• nondisjunction in meiosis I or II (inherit X from one parent, but null-gamete from other parent, usually due to paternal)
• partial monosomy of X chromosome (ie loss of p arm)
• isochromosome of X with two q arms
• no pseudoautosomal regions due to lack of Y and imprinting of Xs
• 67-90% are mosaic

Question 2

Turners-phenotype

Answer 2

-short female with webbed neck, low-set ears, no menstrual periods, limited breast development, infertility, (streak gonads),normal intelligence but sometimes have learning disabilities related to spatial orientation, external genitalia can look normal but secondary sex characteristics (arise from puberty) will be muted

Question 3

Turners-treatment

Answer 3

-human growth hormone, estrogen replacement therapy

Question 4

Turners- prevalence

Answer 4

1:2000-1:5000

Question 5

Klinefelters-genotype and origin

Answer 5

47, XXY due to paternal or maternal meiosis I nondisjunction, or maternal meiosis II nondisjunction (while extra X is inactivated via imprinting, its pseudoautosomal regions escape imprinting and are therefore expressed)

Question 6

Klinefelters-phenotype

Answer 6

“feminized male,” sterility, physical phenotype is subtle but can include wider hips, gynecomastia, tall stature, less body hair, weaker muscles, poor coordination, smaller testes

Question 7

Klinefelters-prevalence

Answer 7

1:500-1:1000 live male births

Question 8

Klinefelters-treatment

Answer 8

testosterone replacement