MCG diseases

Question 1

what is CML - chronic mylegenous leukemia

Answer 1

chromsomes 9 and 22 affected - caused by translocation

Question 2

what is Cri du chat syndrome

Answer 2

limited mental and physical development - caused by deletion of chromosome 5

Question 3

what is trisomy 13

Answer 3

patau syndrome - chromosomal disease - 47 XX +13 or 47 XY +13
Common abnormalities:
include heart defects
incomplete brain development
mean survival ~130 days

Question 4

what is trisomy 18

Answer 4

Edward’s syndrome - chromosomal disease - 47 XX +18 or 47 XY +18
Very rare live birth (95% die in utero) numerous
abnormalities: heart and intestinal development
10% survive for 12 months

Question 5

what is trisomy 21

Answer 5

Down syndrome - chromosomal disease - 47 XX +21 or 47 XY +21
abnormalities:
growth and development delay
cardiac abnormalities
increased risk of acute leukaemia

Question 6

what is huntingtons disease

Answer 6

Caused by mutations at HD locus
Mutant HD gene has MORE THAN 36 repeats of CAG sequence instead of ~28 on exon 1 ofIT15 (Huntingtin)
A patient who is a heterozygote with a single mutant allele (Hh) develops the disease
Mutant huntingtin protein with the pathologically expanded polyglutamine region also causes the normal protein to aggregate leading to neurotoxicity
This is a gain of negative function

Question 7

what is haemophilia A

Answer 7

x-linked recessive disease - blot clotting disorder - mutation in the factor VIII (8) gene on X chromosome

Question 8

what is klinfelters syndrome

Answer 8

47 XXY
^ remember the K looks like an X, therefore has 2 X’s = XXy
can appear normal
causes small testes + limited development of secondary sexual characteristics = infertility

Question 9

what is turners syndrome

Answer 9

45 X
- diagnosis during adult life
- no adolescent growth spurt, no periods = infertility

Question 10

what is XXY syndrome

Answer 10

47 XYY - super male syndrome
because of the extra Y so have more male characteristics
asymptomatic = no symptoms
increased growth - above average height

Question 11

what are 2 mendelian diseases

Answer 11

Cystic fibrosis, Huntington disease
(^ remember they can be autosomal dominant, recessive, or x-linked)

Question 12

what are 2 multifactorial diseases

Answer 12

psoriasis, Chron’s disease.

Question 13

what is an example of a mitochondrial disease

Answer 13

mitochondrial myopathy

Question 14

what is psoriasis

Answer 14

excessive keratinocyte proliferation, and immune cells activation

Question 15

what is fragile x syndrome

Answer 15

genetic mutation in FMR1 is inherited as X-linked dominant
over 200 repeats of the trinucleotide CGG inFMR1, while normal people have 6 to 50 repeats.
Too many CGGs cause the CpG islands at the promoter region of theFMR1gene to become hypermethylated
Hypermethylation turns the gene off, stopping theFMR1gene from producing fragile X mental retardation protein 1.
Loss of this specific protein causes a build-up of toxic proteins and fragile X syndrome.

Question 16

what 2 diseases caused by tandem repeat polymorphism

Answer 16

Huntington’s disease and Friedreich’s Ataxia

Question 17

what is Friedreich’s ataxia

Answer 17

Trinucleotide GAA repeat in intron 1 ofFXN (Frataxin) Autosomal recessive
Repeat diminishes expression of Frataxin
Frataxin - mitochondria, binds iron, required for mitochondrial function
therefore its a type of MITOCHONDRIAL DISORDER

Question 18

what is Charcot-Marie Tooth

Answer 18

first disease system to be related to structural variation in the genome

Question 19

what is sickle cell disease

Answer 19

Recessive disease caused by a SNP in Haemoglobin Beta gene (HBB) - GAG to GTG recoding glutamate to valine β6Glu→Val on translation results in HbS (α2βs2)