Term
|
Definition
- 47, XXY
•Physically normal until puberty
•Tall, long limbs, variably feminine habitus, gynecomastia in 30%
•Verbal comprehension and ability are below normal; reading difficulties
•Poor body image, language difficultiesà shyness, unassertiveness, immaturity
|
|
|
Term
|
Definition
•Not dysmorphic; normal fertility
•XYY males are tall and have an increased risk for educational and behavioral problems
- language delays, spelling problems
- half of XYY boys have lowered IQ, 10-15 pts
- hyperactivity, ADD, impulsiveness; but not
marked by aggression or psychopathology
|
|
|
Term
|
Definition
- 45, X: lyphedema in legs, feet at birth. Webbed neck(remnant of cystic hygroma), low hairline
•Usually average or above average in intelligence
•Deficiencies in spatial perception, perceptual motor organization, and fine motor skills
•Nonverbal IQ lower than verbal
•Need help in mathematics
•Elevated risk of impaired social adjustment
•Hormone therapy for growth, secondary sex characteristics
|
|
|
Term
How do 45 X, fetuses survive to term? |
|
Definition
|
•One possibility: they are not simply 45,X, but are mosaics, including a 46,XX line.
•Another possibility: they are nourished by chromosomally normal (46,XX) placentas. Mosaic variation of placental and embryonic tissue is known to occur.
|
|
|
Term
|
Definition
-due to translocation of the SRY gene to the X chromosome in his father’s meiosis.
|
|
|
Term
|
Definition
-SRY has been translocated out of the Y chromosome she inherited
|
|
|
Term
What do chromosomes look like microscopically in the chromosomal instability syndromes? |
|
Definition
•They show breaks and gaps, involving one or both chromatids
•Sister chromatid exchanges can be apparent in high numbers
•Remarkable radial configurations of conjoined chromosomes look almost like synapsed chromosomes
•Increased rearrangements (deletions, translocations, etc.)
|
|
|
Term
Indications for Cytogenetic Testing..... |
|
Definition
•Spontaneous abortion, stillbirth, neonatal death
•Ambiguous genitalia
•Multiple congenital anomalies
•Failure to thrive (FTT), developmental delay (DD), MR
•Short stature, primary amenorrhea
•Infertility, multiple spontaneous abortions (MSA)
•Previous birth with chromosome anomaly
•Possible balanced translocation in a parent
•Advanced maternal age (AMA)
•Neoplasia, e.g., leukemia (these are acquired chromosomal abnormalities)
|
|
|
Term
Other Reason for Karyotype: 46, XY
female
|
|
Definition
Androgen insensitivity syndrome
(testicular feminization) X-linked
Apparently normal female
external genitalia
Blind vagina
No uterus or uterine tubes
Sparse axillary and pubic hair
Cause: mutation of X-linked androgen receptor gene
|
|
|
