Pedigree.pdf by medicocloud team pediatrics

Pedigree make simplified

2. →Symbols used to pedigree chart


Male female marriage +ve consanguinity deceased female and male Twin
Affected male and female Carrier Unknown sex
Miscarriage
Identical twins
1.Determining if a trait is dominant or recessive:
If the gene is dominant ,every individual that have the triat must have a parent with the same trait
If the gene is recessive ,individuals may express without having parents with same trait
2.Determining if a trait is autosomal or X-linked:
If the gene is X-linked, mostly males will exhibit the trait
If the gene is X-linked, if the affected individual is a female her dad must also exhibit the trait

3. The child of 2 heterozygous parents has a
25% chance of being homozygous
A child of 1 affected parent has 50%
chance of being affected


•50% of a carrier mother’s sons will be
diseased
•50% of a carrier mother’s daughters will be
carrier

Trait often skips generation (hidden in
heterozygous carriers)
Trait is found in every generations
Affected individual transmit the trait
to about ½ of their children
(regardless of sex)

•Trait skips generation
•Affected fathers do not pass to their sons(
father’s x chromosome is inherited only to
daughters
Males and females affected with equal
frequency
Males & females affected with equal
frequency
Males are more often affected than females
Females are carriers (passed from mother to
son)

→Cystic fibrosis
→Thalassemia
→Sickle cell anemia
→Glycogen storage disease
→Phenylketonuria
→Tay-sachs diseases
→There are few autosomal dominant
human diseases,but some rare traits
have this inheritance pattern
→Achondroplasia
→Hereditary spherocytosis
→Huntington chorea

→G6PD deficiency
→Hemophilia A and B
→Duchenne muscular dystrophy
Usually horizontal ie ; affected individuals
are in the same generations
It tends to be vertical i.e.;there are
affected individuals in several
generations
It tends to be oblique ; the affected individual
usually are carriers’s mothers brothers and
sons
→Sex-linked dominant inheritance
→It is a rare pattern
→Its example is vit D-resistent rickets
→Carrier state is only in recessive disorders
→If both parents have recessive traits diseased all offspring
→If both parents have dominant traits diseased some and healthy the other

4. The pedigree above tracks the presence of attached earlobes through a family's generations. Having attached
earlobes is an autosomal recessive trait.
If individual III-6 married a man who was homozygous for unattached earlobes, what is most likely to be true
regarding their children?
a) All the female children will have unattached earlobes, and all the male children will have attached earlobes.
b) The children would all have partially attached earlobes.
c) All of their children would have unattached earlobes.
d) All of their children would have attached earlobes.

The pedigree above tracks the presence of attached earlobes through a family's generations. Having
attached earlobes is an autosomal recessive trait.
If individuals I-1 and I-2 had a fourth child, what is the chance that the child would have attached
earlobes? Choose 1 answer:
a) 50%
b) 0%
c) 75%
d) 100%

5. The pedigree above tracks the presence of attached earlobes through a family's generations. Having
attached earlobes is an autosomal recessive trait.
What is the genotype of individual I-1?
Choose 1 answer:
• ee
• EE
• Ee


The pedigree above tracks the presence of attached earlobes through a family's generations. Having
attached earlobes is an autosomal recessive trait.
What is the genotype of individual II-3?
Choose 1 answer:
• EE
• ee
• Ee


The pedigree above tracks Duchenne Muscular Dystrophy (DMD) through several generations. DMD
is an X-linked recessive trait.
If individuals I-1 and I-2 had another son, what is the chance that he would have DMD?
Choose 1 answer:
a) 25%
b) 50%
c) 100%
d) 0%

6. The pedigree above tracks Duchenne Muscular Dystrophy (DMD) through several generations. DMD
is an X-linked recessive trait.
Based on the pedigree, which of the following is true?
If individual III-1 marries an unaffected, non-carrier female, none of their offspring will have DMD.
If individuals II-4 and II-5 have a fourth child, there is a 50% chance that it will not have DMD.
Individual II-1 is a carrier for DMD.
Individual II-3 has a genotype of



The pedigree above tracks Duchenne Muscular Dystrophy (DMD) through several generations.
DMD is an X-linked recessive trait.
If individual II-3 has a child with a carrier woman, what is the percent chance that the child will
be a daughter with DMD?
a) 25%
b) 100%
c) 50%
d) 0%

7. The pedigree above tracks the presence of dimples through a family's generation. Having
dimples is an autosomal dominant trait.
If individuals II-1 and II-2 have a fourth child, what is the probability that the child will have
dimples?
a) 75%
b) 25%
c) 50%
d) 100%





The pedigree above tracks the presence of dimples through a family's generation. Having dimples is an
autosomal dominant trait.
What is the phenotype of individual III-4?
a) No dimples
b) Dimples
c) dd
d) DD

8. The pedigree above tracks the presence of dimples through a family's generation. Having dimples is an
autosomal dominant trait.
Which of the following individuals is correctly matched with its genotype?
a) II-2 → DD
b) III-2 → Dd
c) II-3 → dd
d) I-1 → Dd




The pedigree above tracks the presence of dimples through a family's generation. Having dimples is
an autosomal dominant trait.
If individuals II-1 and II-2 have a fourth child, what is the probability that the child will have
dimples?
a) 75%
b) 25%
c) 50%
d) 100%

9. The pedigree above tracks Duchenne Muscular Dystrophy (DMD) through several generations. DMD is an
X-linked recessive trait.
What is the genotype of individual II-2?
a) :
?
:
?

b) :
?
:
?

c) :
?
:
?

d) :
?
U



PEDIGREE 1: RED GREEN COLOR BLINDNESS
1. Is the trait controlled by a recessive or dominant allele? EXPLAIN using
specific examples
2. Is the trait autosomal or X-linked? EXPLAIN using specific examples
Write the genotype for each individual on the line beneath it
Use R and r to represent the dominant/recessive alleles

10. PEDIGREE 2 : MYOPIA (nearsightedness)
the following pedigree represents a family history with myopia.
We shall assume the trainsmitted by a single pair of gene
1.write the genotype for each individual on the line beneath it
2. mention mode of inheritance










PEDIGREE 3: POLYDACTYLY
The following pedigree represents a family history with polydactyly. We shall
assume the trait is transmitted by a single pair of genes.
1.Write the genotype for each individual on the line beneath
2.Use E and e to represent the dominant/recessive allel polydactyl
3. Is the trait controlled by a recessive or dominant allele? EXPLAIN using
specific examples
4. Is the trait autosomal or X-linked? EXPLAIN using specific examples