L27 Single Gene Disorders Flashcards
Define ‘consanguineous’.
People descended from the same ancestor.
A genetic study on a large consanguineous Pakistani family with a family history of Familial hypercholesterolemia (FH) identified what?
A common insertion mutation was identified in exon 17 of the LDLR gene.
c.2416_2417InsG
Familial Hypercholesterolemia is an example of what type of point mutation?
Insertion mutation
Cystic fibrosis is an example of what type of point mutation?
Deletion mutation
The majority of cystic fibrosis patients in Western Europe harbour a deletion mutation. What is this mutation?
Phenylalanine (F) is deleted from position 508 in the protein. UUU codon CFTR gene on chr 7.
What causes Duchenne Muscular Dystrophy?
A deletion mutation in an intron induces aberrant splicing of the DMD gene - causing Duchenne Muscular Dystrophy.
What is a homozygote?
An individual with 2 identical alleles for a specific trait.
What is a heterozygote?
An individual 2 different alleles for a specific trait.
Define ‘autosomal’.
Refers to the 44 non-sex chromosomes.
How can you tell whether or not an autosomal gene is dominant?
Look at the family tree: if all affected children have an affected parent then you know it is dominant. If not, it is recessive.
How can you tell whether or not an autosomal dominant gene is X-linked or not?
If affected males all have affected mothers, or affected females all have affected fathers then it is X-linked. Otherwise, it is not X-linked.
What is the chance of inheriting an autosomal dominant gene?
1 in 2
True or false: Recessive gene inheritance can produce an affected individual born to unaffected parents.
True
Why can’t males inherit X-linked mutations from their father?
Because males always receive the Y chromosome from their father.
In what type of mutation is the characteristic not manifested in a heterozygote?
Recessive mutations
