Genetics Flashcards
Numerical
Aneuploidy /loss or gain chromosome
Structural chromosome abnormalities
Translocations / deletions / insertions
Mosaicism
Mutations in embryo not in sex cell
Present in 60% spontaneous misscarriages
Aneuploidy
Numerical abnormality in loss/gain chromosome
Monosomy
Loss of single chromosome (halves protein)
Trisomy
Gain of one chromosome
Downs syndrome (21)
Edwards (18)
Pataus (13)
33%increase protein
Tetrasomy
Gain of two chromosomes
Tolerated
Robertsonian translocation
Only have Q arm
Acrocentric
Cause of Downs Syndrome
90%maternal origin
Non disjunction in meiosis 1 (75%)
Non disjunction in meiosis 2 (25%)
Chromosomal microdeletion disorder
Prader willi syndrome
Deletion of paternal chromosome 15q11-13
Mutation
Heritable change in DNA sequence
Causes monogenic diseases
Polymorphisms
> 1% frequency in each population
Contribute towards complex diseases
Missense mutation
Incorrect replacement of AA
Nonsense mutation
Incorrect sequencing
Insertion mutation
Insertion of Single nucleotide which equates to an incorrect amino acid sequence
Deletion mutation
Malfunctioning protein formed
Huntingtons disease
Autosomal dominant
Vertical transmission
HTT gene affected
27 to >35 glutamine repeats
Genetic anticipation
Age of onset of disease decreases and severity increases
Cystic fibrosis
Autosomal recessive
Delta F508 mutation
X-linked recessive
Haemophillia
Males affected not females
Haemophillia A
F8 —> coagulation factor VIII
Occurs on chromosome X
Haemophillia B
F9 mutation —> coagulation IX
Occurs on X chromosome
Penetrance
Frequency with which symptoms are present
Variable expressivity
Degree of severity
Phenocopy
Same disease /different underlying cause
Prader Willi /Obesity
Epistasis
Interaction between gene mutations and other modifier genes which affect phenotype
Dominant
Gene mutations that results in toxic protein
Recessive
Caused by absence of working protein
Multifactorial disease
Diabetes Mellitus
Genetics / environment
SNP
1 in every 1000 base pairs
> 3.2 million different SNPs between unrelated people
Affect health/ appearance
TCF7L2
SNP increases risk of T2D
Germline mutation
Mutation occurs in the egg/sperm
Genes affect are DNA repair/regulation
BRACA1 /BRACA2
Somatic mutation
Mutations occurring in body cells
Chronic Myelogenous leukaemia
TKinase always active
Cells divide uncontrollably
Pharmacogenetics
Difference between individuals in response to drugs