FOLLOWING PATTERNS

OF INHERITANC

E

GENETIC TESTS

Types of Genetic Tests

a) Karyotype

b) Fluorescence in situ hybridization

c) Gene testing

d) Biochemical testing

GENETIC TESTS

a) KARYOTYPE

- Analysis of chromosome structure and number

GENETIC TESTS

b) FLUORESCENCE IN SITU HYBRIDIZATION (FISH)

- Analysis of details of chromosomal abnormalities

- Using fluorescence to visualize a targeted region of a chromosome

GENETIC TESTS

b) FLUORESCENCE IN SITU HYBRIDIZATION (FISH)

GENETIC TESTS

c) GENE TESTING

- Analysis of mutations in the DNA sequence of a gene

GENETIC TESTS

c) GENE TESTING

GENETIC TESTS

d) BIOCHEMICAL TESTING

- Analysis of abnormal enzymes and other proteins

GENETIC TESTS

CYSTIC FIBROSIS

- Discovery of the gene: 1989, Hospital for Sick Children in Toronto, Lab of Lap-Chee Tsui

- Gene on chromosome 7, mutation of CFTR gene (over 1600 different mutations)

- Genetic test: 85-90% effective

- Affects 1/3600 Canadian children; Carrier 1/25 Canadians

GENETIC TESTS

HUNTINGTON DISEASE

- Gene Huntingtin; first human disease mapped to a chromosome

- Gene on chromosome 4, determined by CAG repeats (greater than 35 is affected)

GENETIC COUNSELLING

GENETIC COUNSELLOR: health care professional specializing in medical genetics and counseling

- Often uses a pedigree to discuss probabilities

- Can also counsel on genetic disorders that are not inherited

GENETIC COUNSELLING

GENE THERAPY: treating genetic disorders by introducing the correct form of the defective gene into a patient’s genome

- Obstacles: type of vector, poor integration of gene into

chromosomes, results are short lived

GENETIC COUNSELLING

GENE THERAPY

1. Normal gene is inserted into a vector (usually DNA of a virus but some elicit immune responses)

2. Vector enters human cells and delivers normal gene

3. Correct protein is made from the new gene

GENETIC COUNSELLING

GENE THERAPY