This document discusses different modes of inheritance in genetics. It defines mode of inheritance as how a genetic trait is passed from one generation to the next. The main modes discussed are autosomal dominant, autosomal recessive, X-linked dominant, X-linked recessive, and mitochondrial inheritance. Autosomal inheritance involves traits determined by autosomal genes, while X-linked involves traits determined by genes on the X chromosome. The document provides examples and descriptions of each mode of inheritance.

1. AMOUD UNIVERSITY
SCHOOL OF DENTISTRY
1ST YEAR STUDENTS
Course Title: DNS6116
Course Code: Genetics
Lecturer: Harun Ismail Warsame(BSc/MPH)

2. Chapter 5: Modes of Inheritance
Lesson 1
Learning Objectives
1. Define modes of inheritance.
2. Discuss the modes of inheritance.

3. Mode of Inheritance
Mode of Inheritance is the
manner in which a genetic
trait or disorder is passed
from one generation to the
next.

4. Categories of modes of
inheritance
Mode of Inheritance includes:
1. Autosomal dominant
2. autosomal recessive
3. X-linked dominant
4. X-linked recessive, and
5. mitochondrial inheritance are
examples.
Each mode of inheritance results in
a characteristic pattern of affected
and unaffected family members.

5. Autosomal vs X-linked
 Autosomal and X-linked are two types of
inheritance patterns that describe the inheritance
of a particular genetic trait from one generation to
the next.
 The main difference between autosomal and X-
linked is that autosomal inheritance is the
inheritance of traits that are determined by
the genes in the autosome whereas X-linked
inheritance is the inheritance of traits
determined by the genes in one of the sex
chromosomes.

6. Autosomal Dominant
Autosomal dominant
inheritance is refers to
genetic conditions that occur
when a variant is present in
one copy of a given gene (i.e.,
the person is heterozygous).

8. Autosomal Recessive
 Autosomal recessive inheritance
refers to genetic conditions that occur
only when variants are present in
both copies of a given gene (i.e., the
person is homozygous for a variant,
or carries two different variants of the
same gene, a state referred to as
compound heterozygosity)

10. Mitochondrial
 Mitochondria make most of the
energy for the cell and have their own
genetic material that is different from
the genetic material found in the
nucleus.
 Mitochondrial DNA is the small
circular chromosome found inside
mitochondria.
 The mitochondria, and thus
mitochondrial DNA, are passed from

12. X-Linked Dominant
 X-linked dominant inheritance refers to
genetic conditions associated with
variants in genes on the X chromosome.
 Example: A single copy of the variant is
enough to cause the disease in both
males (who have one X chromosome) and
females (who have two X chromosomes).
 In some conditions, the absence of a
functional gene results in the death of
affected males.

13. X-Linked Recessive
 X-linked recessive inheritance refers
to genetic conditions associated with
variants in genes on the X
chromosome.
 Example: A male carrying such a
variant will be affected, because he
carries only one X chromosome. A
female carrying a variant in one gene,
with a normal gene on the other X

14. Pedigree
The pedigree shows the
relationships between family
members and indicates which
individuals express or silently
carry the trait in question.