Sex-Linked Disorders Flashcards
1
Q
sex-limited
A
- traits limited to expression in one sex, though genes are in both sexes
- milk production in females
- cryptorchidism in males
2
Q
sex-influenced
A
- expression of traits influenced by sex hormones
* male patterne baldness
3
Q
pseudoautosomal region
A
- X and Y chromosomes have regions at the telomeres that function like other autosomes
- genes here need biallelic expression (preventing males from having turner syndrome phenotype
- crossing over occurs at this region
4
Q
X-linked mutation for hypohidrotic ectodermal dysplasia
A
•females with the mutation may be missing a few teeth or have patches of anhidrosis
•males with the mutation have no teeth, anhidrosis, and sparse hair
anhidrosis=can’t sweat normally
5
Q
y chromosome
A
- SRY gene-> dev of male phenotype
* Yq genes -> spermatogenesis
6
Q
y chromosome can be used for
A
- trace male migration patterns in history
- forensics
- paternity testing
7
Q
key of x-linked dominant disorders
A
•more prevalent in females than males (often lethal to males -> pregnancies lost)
8
Q
key of x-linked recessive disorders
A
- almost exclusively seen in males
- female carriers can have milder symptoms
- rare for female to be homozygote
9
Q
Incontinentia pigmenti
A
- X-linked dominant
- skin redness and blisters -> thickened skin -> hyperpigmentation
- majority are neurologically normal (but can have DD and seizures)
- seen only in females
- NEMO gene
10
Q
x-linked recessive pedigree
A
- more males affected
- grandfather to grandson via female carrier
- no male-male transmission
11
Q
Hemophilia A
A
- x-linked recessive
- excessive bleeding via reduced factor VIII
- <1% factor VIII activity -> severe
- 6%+ -> mild
12
Q
Duchenne Muscular Dystrphy (DMD)
A
- x-linked recessive
- normal at birth
- progressive muscle weakness -> wheelchair by age 10 -> progression to death
- pseudohypertrophy
- respiratory insufficiency
13
Q
DMD gene
A
- Xp21, huge gene, encodes protein dystrophin
- mutations are primarily deletions
- 1/3 of cases are de novo, rest have famale carrier mother
- carrier woman clinically asymptomatic, but may have elevated creatine kinase levels
14
Q
muscle biopsy in DMD
A
- variation in fiber size
- proliferation of CT
- degeneration, necrosis, phagocytosis of muscle fibers
15
Q
cones in eye are maximally responsive to what colors
A
red, green, blue
