Genetics Test 2

Mutations on the same locus but on 2 different alleles

2 different diseases on 2 different genes are similar- genes on different loci. Ex. Retinitis pigmentosa

Different mutations in the same gene can sometimes give rise to different phenotypes

Marriage within family. Ex. 2nd cousins. Diseases said to be 25% higher if consanguinty is present.

People with religious or geographical preferances who marry within. A limited # of people are marrying so this promts inbreeding

Small groups in which the frequency of a certain rare recessive gene is greater than that in the general population

Rr*Rr--> RR+2Rr+rr so every birth= 25% chance of child with disease Rr*rr--> Rr+rr so every birth =50% chance rr*rr--> 100% rr so all diseased

- Rare but possible. A spontaneous mutation is when suddenly disease pops up with no past history. Usually occur in somatic cells so does not pass along to children- de nova mutation

DD*dd--> 100% Dd so all have disease Dd*Dd--> 75% D_ + 25% dd so 75% have disease

Homozygous die before results can occur No DD Usually die in utero or early infancy Ex. Achondroplasia: those who survive are Dd

Generally in autosomal dominant only one sex gets the disease Ex. male limited preccocious puberty