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1. Forensic Serology & DNA Typing…
M.PHOOL BADSHAH

2. Lecture-12
Lineage Markers

3. Introduction
• Autosomal DNA markers, such as the 13 core short tandem repeat
(STR) loci, are shuffled with each generation because half of an
individual’s genetic information comes from his/her father and half
from his/her mother.
• However, the one represent ‘lineage markers’. They are passed
down from generation-to-generation without changing (except for
mutational events).
• Maternal lineages can be traced with mitochondrial DNA sequence
information while paternal lineages can be followed with Y
chromosome markers (Figure 9.1).

5. Types of Lineage Markers
1- mtDNA:
• Cellular components called mitochondria have their own DNA and are
inherited only from the mother. Maternal lineage transmits mtDNA intact
from one generation to the next, in contrast to nuclear DNA, which
recombinants. Because of this, mtDNA is helpful in determining maternal
lineage. When nuclear DNA is unavailable or degraded, mitochondrial
DNA analysis is frequently utilized.
2- Y-Chromosome: Since the Y chromosome is inherited from father to
son, paternal lineage can be traced using Y-DNA markers. When a male
DNA profile is acquired and researchers wish to look into a person's
paternal genealogy or locate male relatives, they frequently use this kind of
study.

6. Importance of Lineage Markers
• In forensic investigations, both mtDNA and Y-DNA analysis can be
useful techniques, especially when working with limited or
deteriorated DNA samples. It's crucial to remember that these
markers only reveal details about particular ancestral lines and do
not give a full picture of a person's whole genetic heritage.
• With lineage markers, the genetic information from each marker is
referred to as a Haplotype rather than a genotype because there is
only a single allele per individual.
• Because Y chromosome markers are linked on the same
chromosome and are not shuffled with each generation, the
statistical calculations for a random match probability cannot
involve the product rule.

7. • Therefore, haplotypes obtained from lineage markers can never be
as effective in differentiating between two individuals as genotypes
from autosomal markers that are unlinked and segregate separately
from generation to generation.
• However, as will be discussed in this chapter and the next one, Y
chromosome and mitochondrial DNA markers do have an important
role to play in forensic investigations.