OTHER TYPES OF INHERITANCE Flashcards
alterations in the number/structure of chromosomes
Cytogenetic Disorders
46XX or 46XY
Normal
an exact multiple of the haploid number (23)
Euploidy
not an exact multiple of 23
Caused by nondisjunction or anaphase lag
Aneuploidy
occurs in gametogenesis; leads to an extra chromosome or loss of a chromosome
Nondisjunction
results in loss of too much genetic materal to have a live birth
Monosomy
mitotic errors early in development which give rise to two or more populations of cells in the same individual
In sex chromosomes is common; autosomal mosaicism not so much
Mosaicism
one segment of a chromosome is transferred to another; 2 types
Translocation
Balanced Reciprocal
Robertsonian
name the translocation
single breaks in two chromosomes w/ exchange of material
Balanced Reciprocal
name the translocation
(aka centric fusion) translocation between two acrocentric chromosomes
Robertsonian
rearrangement involving 2 breaks w/in a single chromosome w/ inverted
reinsertion of the segment
Inversion
terminal ends of chromosome are lost & remaining chromosome circularizes
Ring Chromosome
one arm is missing and the other arm is duplicated
Isochromosome
trisomy 21
Most common chromosomal disorder
95% - from meiotic nondisjunction
Maternal age has a strong influence (>35)
Down’s Syndrome
trisomy 13
meiotic nondisjunction
-Associated w/ increased maternal age
Patau’s Syndrome
trisomy 18
Edward’s Syndrome
5p deletion
- Severe mental retardation
- Cat-like cry
- Congenital heart disease
- Hypertelorism
- Epicanthus
- Retrognathia
Cri-du-Chat Syndrome
an extra X chromosome in a male (47, XXY)/ (48, XXXY)
Most common form of genetic disease involving sex chromosomes
Klinefelter Syndrome
tall and thin; phenotypically normal
XYY Syndrome
complete or partial monosomy of the X-chromosome; (45, X); (46, X,i(Xq))
Turner Syndrome
defect in synthesis of fibrillar collagen
Ehlers-Danlos Syndrome
46XY female
Androgen Insensitivity Syndrome
name this Triple Repeat Mutations
multiple tandem repeats of CGG due to a mutation in the FMR1 gene
29 repeats
50-200 repeats
200-4000 repeats
Fragile X Syndrome
Normal
Premutations of Fragile X
Full Mutations of Fragile X
The conversion of premutation to full mutation occurs
during oogenesis
Clinical signs of fragile X syndrome
- Severe mental retardation
- 2 most common genetic cause
- Most common inherited cause
- Enlarged testes
- Elongated face
- Large everted ears
unique features of fragile X syndrome?
clinically and cytogenetically normal; transmit
disease to grandchildren through daughters
Carrier males
unique features of fragile X syndrome?
30-50% of carrier females are affected
Affected females
