Inheritance of Disease Flashcards
What is the normal nomenclature to describe a normal male and female karyotype?
46, XY and 46, XX
What is the technique used in cytogenetics to visualise karyotype?
Giemsa banding
State the signs & symptoms of Trisomy 21 (Down’s syndrome)
Mental impairment Stunted growth Umbilical hernia Low muscle tone Flat head Brush-field spots in the iris Proportionally large tongue Slanted eyes
Give two examples of tests which could be used to diagnose Down’s syndrome
Amniocentesis
Chorionic villus sampling
Give an example of a monosomy condition
Turner Syndrome, aka “45, X”
In meiosis, one diploid cell generates how many haploid cells?
4
How many nuclear divisions occur in meiosis?
2
Using n = number of chromosomes, show how the n changes during meiotic division
n becomes 2n
Meiosis I = 2n / 2 = n
Meiosis II = n / 2 = 0.5n
Define non-dysjunction
It occurs during meiosis, whereby chromosomes fail to segregate properly. A NUMERICAL aberration
Whilst non-dysjunction is a numerical aberration, state the six STRUCTURAL chromosomal aberrations
Translocation Inversion Deletion (of a segment) Duplication (of a segment) Isochromosome Rings
What does the inheritance pattern look like in a pedigree for a disease which has Dominant Inheritance?
50% risk of disease per birth. Unbroken descent
Give two examples of diseases which have a Dominant Inheritance pattern
Neurofibromatosis I
Tuberous schlerosis
What is the difference between somatic and germline gene mutations?
Somatic - affects only that individual
Germline - in all cells of the body including germ cells. Thefore can be inherited and passed on
What is a “missense mutation”? Give one example of a condition which is underpinned by this type of mutation.
A change in a single Nitrogenous base pair. Results in the substitution of an amino acid.
Sickle cell disease
What is a “nonsense” mutation?
A single substitution of a base, which leads to a premature stop in protein synthesis
