Infertility and Imprinting

Question 1

infertility

Answer 1

inability of achieving conception or inability to sustain a pregnancy through to live birth

Question 2

which chromosomal abnormalities are associated with infertility

Answer 2

45,X
47,XXY
X chromosome abnormalities
Y chromosome microdeletions
translocation - reciprocal and robertsonian

Question 3

genomic imprinting

Answer 3

differential modification of the maternal and paternal genetic contribution to the zygote

some genes are expressed preferentially in either the maternal or paternal genotype

resets during gametogenesis

Question 4

what are things regulated by epigenetic mechanisms

Answer 4

extrinsic changes in primary nucleotide sequence

DNA methylation

histone modification

non-coding RNAs

Question 5

uniparental disomy definition

Answer 5

the inheritance of a pair of chromosomes from one parent with no copy of that chromosome from the other parent

Question 6

types of uniparental disomy

Answer 6

isodisomy = two copies of the same homolog from one parent

heterodisomy = one copy of each homolog from the same parent

segmental = a segment of a chromosome is present from the same parent

Question 7

causes of uniparental disomy

Answer 7

trisomy rescue

monosomy rescue

gametic complementation

somatic crossing over

Robertsonian translocation

Question 8

Prader-Willi Syndrome (PWS)

Answer 8

uniparental disomy example

neonatal hypotonia, intellectual impairment, short stature, hypogonadism, obesity

FACE = narrow bifrontal diameter, short upturned nose, triangular mouth, almond shaped eyes

ETIOLOGY = loss of function of a group of genes normally expressed on the paternal chromosome 15

Question 9

types of prader willi syndrome

Answer 9

70% = deletion of paternal 15

25% = maternal disomy for chromosome 15

~5% = imprinting center defect

Question 10

Angelman Synrome (AS)

Answer 10

example of uniparental disomy

severe intellectual impairment, seizures, ataxic movements, absent speech, wide mout with protruding tongue, widley spaced teeth

disruption in UBE3A gene

Question 11

types of angelman syndrome

Answer 11

65-75% = deletion of maternal chromosome 15

3-7% = paternal UPD for chromosome 15

3% = imprinting defect

5-11% UBE3A mutation

**all of these affect the UBE3A gene in some way