Topic 11 Clinical Genetics Flashcards by ryan seed

If genes have a low penetrance, what does this mean

small infleunce in determining disease susceptibility

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Mendelian disorders are mutations in what genes

single genes

affecting proteins/receptors

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In multifactorial genetic diseases, how many organ systems are affected

one organ system

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if multiple organ systems are affected, what category of genetic disease is it

chromosomal disorder

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if a choroid plexus cyst is found in the brain, what may this indicate

downs

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microdeletion of

22q 11.2

DiGeorges Syndrome

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DiGeorges syndrome 3 symptoms

small mouth
prominent nose
congenital heart defects

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microdeletion

7q 11.23

Williams Beuren Syndrome

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Wide mouth
Upturned nose
Long philtrum
Flattened nasal bridge
Heart defects

Williams Beuren Syndrome

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lack of dystrophin and disorganisation of fibres

X-linked Duchenne muscular dystrophy

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Name 4 autosomal dominant diseases

Adult polycystic kidneys dis

Huntingtons disease

Neurofibromatosis

polyposis coli

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Name 4 autosomal recessive

phenylketonuria

spinal muscular atrophy

congenitial adrenal hyperplasia

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Leber Hereditary Optic Neuropathy

mitochondria mutation

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what is the most common form of cancer

sporadic cancer

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Sporadic cancer is inherited how?

inherited dominantly

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Chorea is what?

What is it found in

Involuntary jerking / twitching

Huntingtons Disease

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CAG trinucleotide repeated passed down from generation to generation leading to earlier onset on symptoms.

what is this phenomenon called

anticipation

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in phenylketonuria, what is absent

Phenylalanine Hydroxylase (PAH)

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Pegvaliaase (Palynziq) is a PEGylated phenylalanine ammonia lyase (PAL) designed for what

reducing phenylalanine in phenylketonuria

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Alkaptonuria has what absent?

Homogentisate dioxygenase

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Neonatal screening is done via what

Tandem mass spectrometry

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the most common inherited metabolic disease

what sort of mutation is it

Familial Hypercholesteraemia

autosomal mutation in LDLR

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Tendinous Xanthomas on hands / heels is a sign of what

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Xanthelasmata + Arcus Cornealis is a sign of what

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Tay Sachs Disease is a disorder of what

lysosomal storage disorder

Tay Sachs Disease what is absent | what does this lead to

Hexosaminadase A deficient accumulation of GM2 in brain death due to pneumonia

where is Tay Sachs Disease prevalent in

jewish population

in the G1 phase, what is duplicated and whats not

cellular contents duplicated chromosomes not

in S phase, what is duplicated

chromosomes 46

What is done in the G2 phase

cell checks for errors | makes repairs

G0 phase

cell cycle arrest

Stages of cell division in order

Prophase Metaphase Anaphase Telophase

"Chromatin condenses into chromosomes "

prophase

"Nuclear envelope disappears | Chromosomes align at equatorial plate"

Metaphase

"Sister chromatids separate | Centromeres divide"

Anaphase

"Chromatin expands | Cytoplasm divides"

Telophase

where does Chiasma form

meiosis

In G banding, what stain is used

Giesma

P arm is what

short arm

Light bands are rich in what? they replicate early in what phase

GC rich (less condensed chromatin) S phase

Dark bands are rich in what? They replicate when

AT rich (condensed chromatin) Replicates late

what phase is the only time when chromosomes are visible

metaphase

in trisomies, by how much is produced extra

1.5x

in deletions/monosomies how much is produced less

0.5x

Tetraploidy = how many chromosomes

in triploidy = how many chromsoomes

Name 5 numerical chromosome abnormalities

``` Edwards (tri18) Patau (tri13) Down (tri21) Turner (45x) Klinefelter (47XXY) ```

for every 16 days from puberty, what forms

4 spermatozoa form

2 Secondary spermacytes form what

4 spermatids

Marfan disease is what disorder? What is the mutation rate relative to

CT disorder relative to older age

Achondroplasia disease is what What is the mutation rate relative to

Disproportionate dwarfism relative to older age

22 mitotic cell division by 5 months of gestation produces how many oocytes

2,600,000 oocytes

how many polar bodies are formed in ovulation and fertilisation

in non disjunction in meiosis 1, what 2 type of cells are formed

2x Disomic gametes 2x Nullsomic gametes

in non disjunction in meiosis 2, what cells are formed

Disomic Nullisomic monosomic 2x normal 2x abnormal

what causes mosaicism

embryo undergoes abnormal seperation of chromosomes in one of its cells normal fertilization

what does mosaicism lead to? what affects the phenotypic expression of it

2 population of cells depends on how early the non-disjunction event was

mosaicism is found in down syndrome.... what % parental origin is it?

92% paternal

mosaicism is found in Edwards syndrome.... what % parental origin is it?

90% maternal

clenched hands and overlapping fingers are found in what syndrome

Edwards Syndrome

Affects midline structures Incomplete lobation of brain Cleft lip Congenital heart disease are found in what syndrome

Patau syndrome

patau syndrome is what % parental origin

85% maternal

Infertility Poor secondary characteristics Tall Gynecomastia is found in what syndrome what is its karotype

klinefelters syndrome XXY

what parental origin is klinefelters syndrome

55% maternal

``` Short stature Primary amenorrhoea Congenital heart disease Low hairline / narrow hip development Hyperconvex nails ``` is found in what syndrome what is its karotype

Turners Syndrome 45, x

in Robertsonian translocation, what happens

fusion of 2 chromosomes from breaking of 2 acrocentric chromosomes close to centromeres

what chromosomes are found in robertsonian translocation

13 / 14 / 15 / 21 / 22

what is lost in robertsonian translocation? what is fused

short arm lost long arm fusion

breaking of 2 non-homologous chromosome is what sort of translocation?

reciprocal

Genetic change associated with neoplastic / cancer disease process is what

Acquired Cytogenetic abnormalities

Acquired Cytogenetic abnormalities example

Chromosome 9 --> 22 Philly gene (CML 90%)

In neoplasm follicular lymphoma, what is translocated?

Bcl-2 oncogene (18-->14)

what happens in neoplasm follicular lymphoma

Neoplastic proliferation of B-lymphocytes as Bcl-2 gene is constantly activated which suppresses cell death

* BM * Lymph nodes * Solid tumours * Chorionic Villi (CVS) are contain what type of cells

Spontaneously proliferating cells

How many days culturing does blood lymphocytes need? How many days culturing does amniotic fluid samples need?

3 days 10 days

name an example of heteroploidy

Neoplasm follicular lymphoma

FISH

Fluorescence in situ hybridization

FISH is done on what 2 cell division phases

metaphase interphase

Comparative genome hybridization can show what

loss/gain of chromosomes regions

name the procedure of DNA PCR and temperatures

Denaturation (94) Annealing of primers (55) Primer extension (72) Amplification (72)

Primers in PCR are what length?

15-30

optimum temperature for DNA polymerase is what

75*

what is used in the termination of a DNA strand why is it used

ddTTTP no 3' hydroxyl group cant form next phosphodiester bond

MEGF10 mutation is found in what

muscular dystrophy

In Oligonucleotide Ligation Assay (OLA), if ligation fails what does this indicate

Missmatch point mutation

what results in point mutation

2 mutant alleles