Topic 20 Flashcards
What is monogenic inheritance?
Inheritance of one gene
What are the four types of Mendelian/monogenic inheritance?
Autosomal recessive (hetero carriers); dominant; X-linked dominant and recessive; complex inheritance (e.g. manx cat)
Types of inheritance
Complete (Manx cat?), Co-dominant (Merle colour in dog associated with deafness), Recessive (typical)
What is polygenic inheritance?
Inheritance of several genes
Main causes of genetic diseases and defects?
Point mutations; Trinucleotide expansion and insertion mutations, Chromosomal abbreviations and abnormalities
What are point mutations?
Frequent and typical; Mis sense; Non sense; Same sense;
Mis sense point mutation
A nucleotide is substituted for another: BLAD e.g. Canine haemophilia
Non sense point mutation
results in a premature stop codon of mRNA - non functional protein
Same sense mutation
“Silent mutation”; no amino acid change
Trinucleotide expansion and insertion mutations
Subsets of unstable microsatellites inserted or doubled in abnormal ways
Chromosomal abbreviations and abnormalities
Leads to genome mutation; caused by mistakes during mitosis, meiosis, fertilization; change in number of chromosomes; Turner’s syndrome
Chromosomal abbreviations and abnormalities in cattle:
BLAD: Bovine Leucocyte Adhesion Deficiency hinders neutrophil function and animals often die of infections of respiratory tract
Chromosomal abbreviations and abnormalities in horse
Lethal white foal syndrome (LWFS); Isoleucine to Leucine; Malformation of the nervous system and bowels; homozygous carrier foals; white foals; occurs in American Paint Horses
Chromosomal abbreviations and abnormalities in sheep
Spider Lamb Syndrome (SLS); callypige to muscular dystrophy
Chromosomal abbreviations and abnormalities in dogs
Urate urolithiasis to defective purine metabolism
Urate urolithiasis to defective purine metabolism
