Extra information

Question 1

Haplotypes

Answer 1

• Haplotypes are used in Y STR Calculations as no recombination events occur with these chromosomes. Therefore all STRs on the Y chromosome are linked and the Y chromosome profile is then treated as a haplotype

Loci: A B
Alleles: A, O B, O
Haplotype: AB, AO OB, OO

Allelic frequencies of A and B:
A= AB + AO
B= OB + OO

Degree of linkage disequilibrium would be:
∆AB= ABOO - AOOB
(LD= non-random association of alleles at different loci)

• Haplotype frequency calculates how many times in the entire Y chromosome profile (haplotype) has been seen in an entire population
• Haplotype data on local populations, however small sample size, hence global Y chromosome databases

Question 2

Rapidly mutating Y-STRS

Answer 2

Normal autosomal Y-STRs are hard to discriminate between individuals due to the low mutation rate

Hence RM-YSTRs used to help discriminate between these paternally related males in paternity and forensic casework due to high mutation rates

Question 3

mtDNA analysis

Answer 3

mtDNA is sequenced using MPS of multiplex PCR-generated libraries

New approaches are looking at capture hybridisation and primer extension capture methods followed by MPS (able to target smaller amplicons)

mtDNA is good for DVI and human identification cases as due to maternal relatins holds less information than normal autosomal STR typing