This document discusses various patterns of inheritance including Mendelian patterns like autosomal dominant, autosomal recessive, X-linked, and Y-linked inheritance. It also covers non-Mendelian inheritance patterns such as mitochondrial, genomic imprinting, unstable repeat expansions, uniparental disomy, mosaicism, and multigenic inheritance. For each pattern of inheritance, the key features are defined.

1. PEDIGREE ANALYSIS
AND
PATTERNS OF
INHERITANCE
Mrs. Jennifer Lawrence Tellis
Institute of Science, Nirma University

2. PEDIGREE

3. BASICS OF PEDIGREE

5. PATTERNS OF INHERITANCE
Mendelian
Autosomal
dominant
Autosomal
recessive
X-linked
Y-linked
Non-Mendelian
Mitochondrial
inheritance
Genomic
imprinting
Unstable repeat
expansions
Uniparental disomy
Mosaicism
Multigenic
inheritance

7. AUTOSOMAL DOMINANT INHERITANCE

8. FEATURES:
1. Vertical transmission
2. Affected males equivalent
to affected females
3. Male to male transmission

9. 1. Vertical transmission
2. Affected males equivalent to
affected females
3. Male to male transmission
4. Pleiotropy
FEATURES:

10. FEATURES:
1. Vertical transmission
2. Affected males equivalent to
affected females
3. Male to male transmission
4. Pleiotropy
5. Variable expressivity

11. FEATURES:
1. Vertical transmission
2. Affected males equivalent to
affected females
3. Male to male transmission
4. Pleiotropy
5. Variable expressivity
6. Decreased penetrance

12. FEATURES:
1. Vertical transmission
2. Affected males equivalent to
affected females
3. Male to male transmission
4. Pleiotropy
5. Variable expressivity
6. Decreased penetrance
7. Recurrence risk

13. AUTOSOMAL RECESSIVE INHERITANCE

14. FEATURES:
1. Horizontal transmission
2. Affected males equivalent
to affected females
3. Consanguinity

15. FEATURES:
1. Horizontal transmission
2. Affected males equivalent to affected
females
3. Consanguinity
4. Recurrence risk

16. X- LINKED INHERITANCE
• Dominant / recessive will depend on the phenotype in heterozygous
females
• Considered a spectrum of disorders instead of dominant or recessive

17. FEATURES:
1. Dominant or Recessive?

18. FEATURES:
1. X-linked recessive
inheritance
2. Male to male transmission
is not seen; variant is
inherited from one male
to another via a female
carrier

19. FEATURES:
1. X-linked recessive inheritance
2. Male to male transmission is not seen;
variant is inherited from one male to
another via a female carrier
3. Affected females in
special cases: Turner
syndrome, X-autosome
translocation, etc.

20. FEATURES:
1. X-linked recessive inheritance
2. Male to male transmission is not seen;
variant is inherited from one male to
another via a female carrier
3. Affected females in special cases: Turner
syndrome, X-autosome translocation,
etc.
4. Recurrence risk

21. FEATURES:
1. X-linked dominant
inheritance
2. Similar to autosomal
dominant pedigree,
except, male to male
transmission is not seen

22. Y-LINKED INHERITANCE:
phenotype transmitted from father to son

23. MITOCHONDRIAL INHERITANCE
• Maternal inheritance: mutated mitochondria transmitted from mother to
offspring

24. FEATURES OF MITOCHONDRIAL INHERITANCE
1. Maternal inheritance
2. Replicative segregation
3. Homoplasmy
4. Heteroplasmy
5. Threshold expression
6. Genetic bottleneck

25. UNSTABLE REPEAT EXPANSIONS
• Unstable expansion of repeating units of three or more nucleotides in
tandem
• Features:
1. Anticipation
• Examples:
1. Fragile X syndrome: CGG
2. Huntington disease: CAG

26. GENOMIC IMPRINTING
• Phenotypic expression of alleles depends on the parent of origin
• Epigenetic phenomenon
• Examples: Angelman syndrome, Prader- Willi syndrome

27. UNIPARENTAL DISOMY
Inheritance of
both homologous
chromosomes
from the same
parent

28. MOSAICISM
• Presence of more than one cell type
• Error in mitosis after conception
• Somatic cells/ germline cells
• Variable severity of clinical features

29. MULTIGENIC INHERITANCE
• This is a result of combined
effect of more than one gene
• Complex traits are a result of
environmental factors and
multiple genes