Term
| chromosomal sex is determined at ___________ |
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Definition
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Term
| Other aspects of sex (gonads and external genitalia) depend on the interaction of genes and environmental factors, especially ___________ |
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Definition
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Term
| The chromosomal sex of an individual (XX or XY) can differ from the ___________ sex |
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Definition
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Term
| Sex of an individual is defined at three levels, what are they? |
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Definition
-chromosomal sex
-gonadal sex
-phenotypic sex |
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Term
| For the first 7 or 8 weeks, the embryos is neither male nor female, why? When does sexual differentiation begin? |
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Definition
-two undifferentiated gonads
-both male and female reproductive duct systems develop
-sex differentiation begins at week 8 |
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Term
| ___________ cause gonads to develop as testes or ovaries, establishing gonadal sex |
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Definition
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Term
| What is the SRY gene? Where is it located? What is its job? |
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Definition
-sex-determining region of the Y chromosome
-located near the end of the short arm of the Y chromosome
-Plays a major role in causing the undifferentiated gonad to develop into a testis |
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Term
| What the is a male sex hormone, a steroid hormone produced by the testis? What does it stimulate the development of? |
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Definition
-Testosterone
-Mesonephric ducts (formerly known as the Wolffian ducts) in the embryo; the male ducts |
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Term
| What is the job of Anti-Mullerian Hormone (AMH)? |
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Definition
| It is a hormone produced in the developing testis that causes the breakdown of the paramesonephric ducts (formerly known as the Mullerian ducts) in the embryo; the female ducts |
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Term
| In the absence of testosterone and the absence of AMH, what happens in female development? |
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Definition
-the mesonephric (Wolffian) duct system degenerates
-the paramesonephric (Mullerian) duct system forms female reproductive system |
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Term
| The genetic sex of an embryo is established at ___________ |
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Definition
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Term
| What is the term for an individual with both ovarian and testicular tissue? |
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Definition
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Term
| What is the term for an individual with a 46,XX karyotype and normal ovarian tissue, but with ambiguous or male external genitalia? |
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Definition
| Female pseudohermaphrodite |
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Term
| What is the term for an individual with a 46,XY karyotype and normal testicular tissue, but with ambiguous or female external genitalia ? |
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Definition
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Term
| In patients with ambiguous development of the external genitalia, a __________ is important for determining the sex chromosome constitution of the patient and to identify chromosome abnormalities frequently associated with dysgenic gonads. |
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Definition
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Term
| What is the term used to describe hermaphroditism and pseudohermaphroditism? |
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Definition
| Disorders of sex development (DSD) |
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Term
| Female pseudohermaphroditism is usually do to what? WHat type of inherited disorder is this? |
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Definition
-Congenital adrenal hyperplasia (CAH)
-inherited autosomal recessive disorder of hormone synthesis by the adrenal glands |
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Term
| Patients with CAH have a mutation in what gene? This causes a lack of which enzymes? And this leads to...? |
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Definition
-CYP21A2 gene
-lack of 21-Hydroxylase
-needed by the adrenal gland to produce the hormones cortisol and aldosterone. Without these hormones the body produces more androgen, resulting in masculinized external genitalia of female infants |
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Term
| In male pseudohermaphroditism, the gonads are exclusively __________, but the genital ducts and/or external genitalia are __________/__________ |
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Definition
testes
incompletely masculinized |
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Term
| Male pseudohermaphroditism can be caused by what 4 thing? |
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Definition
-disorder of the testis development during embryogenesis
-abnormalities of the gonadotropins
-inherited disorders of testosterone biosynthesis and metabolism
-abnormalities of androgen target cells |
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Term
| What is the name for the syndrome that consists of a mutation in the X-linked androgen receptor (AR) gene that causes XY males to become phenotypic females? |
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Definition
| Androgen insensitivity syndrome |
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Term
| In androgen insensitivity syndrome, the gonads develop into testes and produce testosterone, DHT and AMH. which of these can the body respond to and to which can it not? |
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Definition
-the body still responds to AMH, causing the female duct system to degenerate
-The body cannot respond to testosterone and DHT because the AR gene is defective, so the male duct system degenerates and the genitalia develop as female structures |
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Term
| What is dosage compensation? |
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Definition
A mechanism that regulates the expression of sex-linked gene products.
-Human females have random inactivation of one X chromosome in all somatic cells to balance the expression of X-linked genes in males and females |
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Term
| WHat is the first step of the two step process of x chromosome inactivation? |
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Definition
| counting the number of x chromosomes present by pairing x chromosomes |
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Term
| In the second step of x chromosome inactivation, what is the purpose of the XIST gene? Where is it located? |
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Definition
-the inactivated chromosome is coated with XIST RNA
-THe XIST gene is located in a region of the X chromosome called the X inactivation center (Xic)
-XIST is only expressed from the inactive X chromosome and it serves to silence most (but not all) genes on the inactive X |
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Term
| What sex has barr bodies? What are they? |
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Definition
-XY males have no inactive X chromosomes, so no Barr bodies
-they are a densely staining mass in the somatic nuclei of mammalian females
-an inactivated X chromosome, tightly coiled |
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Term
| In females, some cells express the mother's X chromosome and some cells express the father's X chromosome, this can be described as a __________ |
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Definition
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Term
| Is inactivation permanent? |
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Definition
| Yes, all descendants of a particular cell have the same X inactivated |
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Term
| sex chromosome abnormalities, like abnormalities of the autosomes, can be either __________ or __________ and can be present in all cells or __________ form |
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Definition
numerical
structural
mosaic |
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Term
| What are 4 clinical indications that raise the possibility of a sex chromosome abnormality and the need for cytogenetic and molecular analyses? |
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Definition
-delayed onset of puberty
-amenorrhea
-infertility
-ambiguous genitalia |
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Term
| What are the most common sex chromosome defects in liveborn infants? What is second |
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Definition
trisomies (XXY, XYY, XXX)
monosomy for the X |
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Term
| Why are phenotypes associated with sex chromosomes, in general, less severe than those associated with comparable autosomal disorders? |
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Definition
| bc of x chromosome inactivation and the low gene content of the Y |
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Term
| Between the X and Y chromosomes, which is required at least one copy for development and which is not necessary for survival? |
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Definition
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Term
| What is the inheritance, genetic etiology, and frequency of Klinefelter Syndrome (47, XXY)? |
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Definition
-inhertiance: chromosomal
-GE: 47, XXY karyotype due to nondisjunction in maternal or paternal meiosis I; some have additional X chromosomes
F: 1 in 500-1,000 male live births |
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Term
| Individuals with Klinefelter syndrome have a __________ phenotype but may fail to develop __________/__________ characteristics |
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Definition
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Term
| Give some physical characteristics of a pt with klinefelter syndrome |
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Definition
-tall and thin with long limbs
-small testes and produce few or no sperm
-some degree of breast development
-learning disabilities |
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Term
| What is management for a pt with klinefelter syndrome? |
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Definition
-treatment with testosterone to promote male secondary sexual development
-counseling regarding probable infertility
-early intervention manage learning disabilities |
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Term
| What is the inheritance, genetic etiology, and frequency of 47, XYY syndrome? |
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Definition
-I: chromosomal
-GE: 47, XYY karyotype due to nondisjunction in paternal meiosis II
-F: approx 1 in 1,000 male live births |
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Term
| Individuals with XYY have a __________ phenotype and are fertile. They tend to have __________ disabilities and __________ problems. May have a relatively __________ stature |
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Definition
male
learning
behavioral
tall |
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Term
| What is the management for 47, XYY syndrome? |
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Definition
anticipatory guidance and support for learning disabilities
recurrence is rare and can be detected by prenatal chromosomal analysis |
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Term
| What is the I, GE, and F for trisomy X (47, XXX) |
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Definition
-I: chromosomal
-GE: karyotype due to nondisjunction in maternal meiosis I
-F: approx 1 in 1,000 female live births |
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Term
| What is the phenotype in trisomy X? Are they fertile? how tall are they? learning problems? |
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Definition
-female
-yes
-slightly above average, but not abnormal phenotypically
-70% have some learning problems |
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Term
| what is the management for trisomy x? |
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Definition
anticipatory guidance and support for developmental impairment
-recurrence is rare and can be detected by chromosomal analysis |
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Term
| What is the I, GE, and F of turner syndrome (45, X and other variants) |
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Definition
-I: chromosomal
-GE: 45, X karyotype due to nondisjunction or loss of a structurally abnormal X or Y chr
-70-80% of pts conceived from sperm lacking a sex chromosome
-many are mosaics, with a cell line containing 46 chromosomes with a structurally abnormal X or Y
-F: 1 in 3,000-4,000 female live births |
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Term
| Pts with turner syndrome have what phenotype? What may they fail to develop? |
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Definition
-female
-seconday sex characteristics (pubic and axillary hair) |
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Term
| Describe the stature of pts with turner syndrome? Are they fertile? What cardiac anomaly is common? Renal? |
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Definition
-short
-primary amenorrhea and infertile
-coarctation of the aorta
-renal anomalies |
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Term
| What causes the webbing of the neck seen in pt's with Turner Syndrome? |
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Definition
| lymphedema and redundant nuchal skin |
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Term
| Do turner syndrome pts have learning disabilities? |
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Definition
-yes, esp visual-spatial perceptual problems
-intelligence is normal |
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Term
| What is the management for Turner syndrome? |
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Definition
| -treatment with hormones to promote secondary sexual development; surgical correction of congenital heart defects; anticipatory guidance and early intervention to overcome learning disabilities; GH therapy for stature |
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