Chap: 6 the chomosomal and genomic basis of disease Flashcards

1
Q

two chromosomes inherited from two identical sister chromatids

A

isodisomy

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2
Q

both homologues from both parents are present

A

heterodisomy

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3
Q

Heterodisomy indicates what type or error?

A

meiosis I error

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4
Q

Isodisomy indicates what type of error?

A

meiosis II error

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5
Q

Proximal iUPD (with crossing over) results from what type of error?

A

meiosis II error

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6
Q

Distal iUPD (with crossing over) results from what type of error?

A

meiosis I error

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7
Q

occurs from misalignment of and subsequent recombination between the flanking segmental duplications

A

non-allelic homologous recombination

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8
Q

7q11.23 deletion

A

Williams syndrome

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9
Q

15q11-13 deletion

A

Prader-Willi/Angelman Syndrome

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10
Q

Autism/DD

recurrent microdeletion syndrome

Macrocephaly is common

chiari malformation and cerebellar ectopia most frequent brain abnormalities

vertebral anomalies most common birth defect

A

16p11.2 deletion

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11
Q

17p11.2 deletion

A

Smith-Magenis Syndrome

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12
Q

feeding difficulties- infamts

prolonged napping-infants

upper body squeeze/hug

A

17q11.2 deletion

Smith-Magenis

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13
Q

Smith-Magenis Syndrome can also result from intrageneic pathogenic variants in

A

RAI1

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14
Q

Potlocki-Lupski Syndrome

A

17p11.2 duplication

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15
Q
  • preauricular pits and/or tag
  • anal atresia,
  • iris coloboma
  • heart defects
  • renal anomalies
A

Cat-eye-Syndrome

CES is usually associated with a supernumerary bisatellited marker chromosome containing material of chromosome 22 (idic(22)(pter→q11.2::q11.2→pter)), which results in partial tetrasomy 22.

22q11.2 duplication

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16
Q

3.5Mb deletion

Y chromosome

Oligozoospermia/Azoospermia/Infertility

17
Q

true/False: Most cases of cri du chat are sporatic

A

True

5p deletion

breakpoints are highly variable

18
Q

inv(9)(p11q12)

A

considered a normal variant

does not appear to have signifigant risk for miscarriage or unbalanced offspring

19
Q

inv(3)(p25q21)

A

carriers are normal

offspring with 3q21 duplication and 3p25 deletion = abnormal phenotype

offspring with opposite not viable.

40% eprirical risk of abnormal pregnancy outcome for carriers

20
Q

absence of paternally derived 15q11-q13

A

Prader-Willi Syndrome

infancy feeding difficalties

childhood hyperphagia and obesity

hypotonia

cognitive impairment

short stature

dysmorphism

21
Q

hypermethylation of one copy of SNRPN

A

Prader-Willi syndrome

22
Q

NIPTs noted for trisomy 15

Amniocentesis chromosomal analysis is normal

What condition would you be concerned about?

A

Prader-Willi syndrome

Maternal uniparental disomy via trisomy rescue

Loss of paternal chromosome 15 from conceptus with chromosome 15 trisomy secondary to maternal nondisjunction (meiosis II non-disjunction)

23
Q

which molecular case of Prader-Willi has the highest recurrance risk?

A

Imprinting center defects: as high as 50%

deletion and maternal UDP about 1%

parents with balanced translocation: up to 25%

24
Q

Majority of case of Beckwith-Weidmann Syndrome are secondary to what molecular defect

A

Loss of maternal methylation of IC 2: 50%

paternal UPD for 11p15: 20%

Gain of methylation in maternal IC 1: 5%

heterozygous maternally inherited variant: CDKN1C: 40% familial cases; 5-10 % in cases with no family history

25
Maternally inherited mutations in ____ account for about \_\_\_\_% of patients with Angelman Syndrome
*UBE3A* 10%
26
genetic recombination occuring outside the _______ of the sex chromosome. Result in XX males and XY females
pseudoautosomal regions
27
which of the following chromosomal inbalances may have greater clinical signifigance imbalances on Xp or imbalances in Xq
many more genes “escape” inactivation on distal Xp (as many as 50%) than on Xq (just a few percent) **_imbalance for genes on Xp may have greater clinical significance than imbalance for genes on Xq_**, where the effect is largely mitigated by X inactivation
28
most females with a XY karyotype have a normal ____ gene.
normal
29
The *DAX1* gene found on Xp21.3 is a transcription factor that has a ____________ role in gonadal sex development
dosage-sensative ## Footnote *duplications of DAX1 supresses the function of SRY leading to failure of testicular development; leading to ovarian development*
30
SOX9 mutations found on chromosome 17 are associated with this skeletal malformation, leading to complete gonadal dysgenesis.
camptomelic dysplasia 46,XY