DR Jai Prakash soni Curriculum Vitae
professor
Head unit IV
Dep Pediatrics Dr S N Medical , Jodhpur
Contact: +91-9828034098
E-mail: [email protected]
Education
• M.B.B.S in 1983 Dr S.N. Medical college, Jodhpur
• M.D. Pediatric 1987, Dr S. N. Medical college, Jodhpur
Major posts/responsibilities:
• Organizing secretary of Live Workshop on Fetal medicine and
interventional sonography in 2009 and 2010 at Jodhpur.
Thalassa – Gen 2012 at Jodhpur
Special training:
• Specialized training Pediatric cardiology
at AIIMS, Delhi
Twinty four publications in national journals
Pediatric cranial Sonography and fetal echocardiography – field of
special interest.
Speaker : First international congress on fetal medicine, New Dehli
Dr. Jai Prakash Soniprofessor
Unit head IV
Dr S N Medical collegejodhpur
Pedigree
Pedigree - “ pie de grue ” (Fr. crane’s foot)
It is a graphic depiction of relation
between family
members, that is
How they are
biologically/legally
related to
each other through generations.
Pedigree
chart
Serve as a
reference
of
social and
biological
relationships.
Pedigree is thesymbolic language
used for clinical genetic services
and
human genetic research.
To determine the
mode of
inheritance:
Autosomal Dominant
Autosomal Recessive
Partial dominance
Sex-linked
Mitochondrial
Help to
determine
the risk or
probability
of an
affected
offspring
for a given
cross. Determining genotypes for various
individuals
How different symbols are used
while drawing
Pedigree Chart ?
Pedigree Standardization Task Force
Organized by the National Society of Genetic Counselors
Recommendations for universal standards in human pedigree nomenclature
Had provided Guide lines
For drawing pedigree.
While drawing “Pedigree chart”
One should follow rule of thumb
Symbols used for drawing Pedigree chart are
Male family member is
represented by a square .
•American Journal of Human Genetics 56:745-752, 1995
Female family member is
represented by a Circle .
Gender not Specified
Other Symbols used in a Pedigree Chart are
X-linked – Carrier are depicted Central dot in a circle.
Autosomal carrier Represented by central vertical line.
Deceased/Death sib is represented with slash
Shaded circles or squares represents affected individuals.
Other Symbols used in a Pedigree Chart are
Other Symbols used in a Pedigree Chart are
Affected fetus
Representation of 2 or more conditions
Normal relation between couple is
demonstrated by straight line
Consanguineous mating is
demonstrated by two Parallel lines
Broken Relationship between couple
is demonstrated by broken line
Relationship Between Couple is
Depicted by connecting lines
Marriage line
Divorce
consanguineous
Relationships between
parent & offspring is depicted as
The pedigree of Biological parents
with one sib will be
Age Personally examined
Descent line
Family tree
•American Journal of Human Genetics 56:745-752, 1995
Relation ship between parent’s and sib is
demonstrated by Connecting line.
o Vertical line drawn
represents a child.
Horizontal line across sib will represent
total number of children in family(siblings).
Relationships between
parent & offspring is depicted as
The pedigree of Biological parents
with one sib will be
When child is Adopted From family Member
Pedigree will like as shown below
?If Biological parents not known the pedigree
Will be depicted as
When couple do not have children
Pedigree will be depicted as
[ ]
When child is Adopted out of the family Members
Pedigree will be depicted as
Symbols for Twin sib
Twins
Monozygotic
Dizygotic
Unknown
zygocity
?
D
P
P
P
D
Donor sperm
Donor ovum
S
P
Surrogate only
D
D
P
P
Surrogate ovum donor
Surrogate ovum donor
P
P
Planned adoption
D D
[ ]
Donor sperm and ovum
Rule of thumb while drawing a pedigree chart.
Tips for drawing
Male partner is drawn to the left of female.
Family member of each generation should be on the same plane
Tips for drawing
Siblings are drawn in birth order.
Each generation is identified by Roman numerals
I
II
III
IV
by Arabic numerals
I
II
III
IV
1 2 3 4 5
Individuals in each generation are
Numbered from the left
Pedigree chart
The affected individuals are denoted first by Generation then by their Arabic numbers
II3
IV2 and IV4
I
II
III
IV
1 2 3 4 5
Usually three generations pedigree is drawn for fruitful
conclusion.
Generations are extend back as far as possible if a significant health problem is identified.
How to draw a pedigree ? “Example”
Anita have two brothers and two sisters.
She married to Deepak.who is her maternal aunt’s son
(first cousins).How this pedigree will be drawn ?
Anita Sunil Meeta Anil SunitaDeepak
Reeta
Anita have two brothers and two sisters. She married to Deepak.who is her maternal aunt’s son
(first cousins)
Anita and Deepak are expecting their second child.
Their first child, Rahul has cystic fibrosis.
How Pedigree will be look like ?
P
Anita
Rahul
Deepak
cystic fibrosis second pregnancy
Anita has two brothers, Anil, Sunil and a sister Sunita.
How Pedigree will be look like ?
Anita has two brothers, Anil, Sunil and a sister Sunita.
P
Anita
Rahul
Deepak
P
Anitha Sunil Meeta Anil Sunitha
PinkyRahul
Deepak
Reeta
PP
Anitha Sunil Meeta Anil Sunitha
PinkyRahul
Deepak
Reeta
Sunita
Anil and Sunita are unmarried.
Sunil is married to an unrelated woman Meeta and has a two year old
daughter Pinky.
How Pedigree will be look like ?
P
Anita Sunil Meeta Anil Sunita
PinkyRahul
Deepak
Reeta
Anil and Sunita are unmarried. Sunil is married to an unrelated woman Meeta
and has a two year old daughter Pinky.
“Drawing A complete pedigree is often a work of great labour, and in its finished
form is frequently a work of art.”
Karl Pearson (1912)
Mother’s genes Father’s genes
Child’s genes
Under what circumstances interpretation of a pedigree
Is required ?
Interpretation of pedigree is required
for Various MENDELIAN inheritance
patterns ------ Autosomal dominant
e.g., Huntington’s Disease
Autosomal recessive
e.g., PKU, Tay-Sachs, albinism
X-linked recessive
e.g., color-blindness, hemophilia
X-linked dominant
e.g., hypophosphatemia
Y-linked -LERI WEIL DYSCHONDROSIS
Organelle - Mitochondrial disorders
HOW TO READ THESE VARIOUS MENDELIAN INHERITANCE
PATTERNS ON A PEDIGREE CHART ?
It is not magic to understand pedigree, But one require little practice to understand how to read pedigree ,
What type of inheritance is This ?
AUTOSOMAL DOMINANT PEDIGREE
1) Both sexes are involved
2) Generation not skipped
3) "Vertical" transmission
4)Spontaneous mutation
5)50% risk for affected child, if parent affected
Counseling The risk of passing an Autosomal disorder to
next generation from an affected Person is 50%,
but manifestation of disease is influenced by
1.Disease penetratnce – all & non phenomenon
2.Variable expression
3.Anticipation
4.pleiotropy – different mutation in same gene
cause different manifestation-
LMNA gene ( encode lamin A/C) & X filamin A
gene
Emery –dreifuss muscular dystrophy, limb girdle
muscular dystrophy, dilated cardiomyopathy,
Hutchinson Gilford progeria.
WHAT IS DOMINANCE?
Dominance & recessiveness are relative term and are used
Only when one allelle is compared with the other
On chromosome at each locus there can be many genes,
Which are known as “ALLELES”
Person with Genotype AA, Aa (Heterozygote) “ALLELES”
Phenotype will be similar, as A dominant over
Normal “a” ( wild type) allele.
Such manifestation of gene in heterozygote state are
known as “Dominant” gene.
Person with Genotype aa (Homozygote) “ALLELES”
Phenotype will be of Normal
Dominant
If both partners are affected & have an unaffectedchild, it must be a heterozygous dominant pedigree:
“A” is the dominant mutant allele and
“a” is the recessive wild type allele.
It means both parents are “Aa” and the normal childis “aa”.
If every child is affected than bot parents should behomozygous and will have “AA” dominantgenotype.
Manifestation of Dominant gene depends on –
Penetrance : though person carry mutant gene but either gene donot manifest or
disease manifetst at late age – Huntington chorea,
Myotoinic dystrophy
Spinocerebellar ataxia
Thus risk of having clinically affect offspring is < 50%.
Variable expressivity: The severity of diseases may very in affected person of a
family. One can have all features while other may have only
one feature – Neurofibromatosis.
This is because of interaction between causative “Gene” and modifier “Gene” and
environment. It means single gene disorder are not truly govern by
one gene but real senesce they are oligogenic.
Manifestation of Dominant gene depends on –
Anticipation : If the severity of disease increases as it is passed
down the generation.
Myotonic dystrophy –
Grand parents at old age – cataract and muscular weakness
Mother - mild muscle weakness
Offspring - severe hypotonia during neonatal period.
AUTOSOMAL DOMINANT diseases• HUNTINGTON DISEASE
• NEUROFIBROMATOSIS
• MYOTONIC DYSTROPHY
• TUBEROUS SCLEROSIS
• POLYCYSTIC KIDNEY
• HEREDITARY SPHEROCYTOSIS
• VON WILLEBRAND DISEASE
• MARFAN SYNDROME
• EHLERS-DANLOS SYNDROMES(some)
• OSTEOGENESIS IMPERFECTA
• ACHONDROPLASIA
• FAMILIAL HYPERCHOLESTEROLEMIA
• ACUTE INTERMITTENT PORPHYRIA
Pseudo dominance
What type of inheritance is This ?
AUTOSOMAL RECESSIVE PEDIGREE
1) Both sexes are involved
2) "Horizontal" transmission
3) Parents are heterozygous for trait
4) For affected child risk is 25% risk
with each pregnancy.
WHAT IS RECESSIVENESS?
Dominance & recessiveness are relative term and are used
Only when one allelle is compared with the other.
On chromosome at each locus there can be many genes,
Which are known as “ALLELES”
Person with Genotype Aa (Heterozygote) “ALLELES”
Phenotype will not have manifestation of
Normal “a” ( wild type) allele.
Only when Person’s Genotype is “aa” (Homozygote)
“ALLELES” or compound Hetreozygocity.
Phenotype will have manifestation of
Normal “a” ( wild type) allele.
aa
aa
Aa
Aa
Aa
Only a recessive trait can skip a generation
If neither of these events occurs in
a pedigree then trait could be dominant.
AUTOSOMAL RECESSIVE
CF PKU GALACTOSEMIA HOMOCYSTINURIA LYSOSOMAL STORAGE Α-1 ANTITRYPSIN WILSON DISEASE HEMOCHROMATOSIS GLYCOGEN STORAGE
DISEASES
Hgb STHALASSAEMIASCONG. ADRENAL HYPERPLASIAEHLERS-DANLOS (some)ALKAPTONURIANEUROGENIC MUSC. ATROPHIESFRIEDREICH ATAXIASPINAL MUSCULAR ATROPHY
Recessive
If two unaffected people have an affectedchild, it is a recessive pedigree:
“R” is the dominant wild type allele and
“ r” is the recessive mutant allele.
Both parents are Rr and the affected child is rr.
What type of inheritance is This ?
SEX LINKED PEDIGREE
1) Only Males are affected
2) Generation skipping does not matter.
SEX (“X”) LINKED
If only male partner is affected then all his sons will be normal and daughters will be carrier.
The “Y” chromosome is not homologous to the “X” that’s why the concept of
dominant / recessive has no meaning here.
Heterozygous females have no phenotypic expression (carriers)….usually, this means autosomal “recessive”, right ?
Pedigree of an X-linked recessive disorder
Son not
affected
Daugther
carrier
1/2
grandsons
affected
Father affected
SEX (“X”) LINKED
DUCHENNE MUSCULAR DYSTROPHY
HEMOPHILIA , A and B
G6PD DEFICIENCY
AGAMMAGLOBULINEMIA
WISKOTT-ALDRICH SYNDROME
DIABETES INSIPIDUS
LESCH-NYHAN SYNDROME
FRAGILE-X SYNDROME
What type of inheritance is This ?
are characterized by the following pedigree
pattern:
(1) Affected males transmit the disease to all
their daughters but none of their sons.
unlike dominant autosomal disorders where
daughters and sons have an equal probability
to inherit the disease.
X-linked dominant disorders
(2) Affected females are mostly heterozygous.
When married to unaffected males, they transmit
the disease to 50%(1/2 )of their sons and (1/2) of
their daughters (same pattern as for autosomal
dominant disorder).
X-linked dominant disorders
Note: X-linked dominant disorder are rare
traits in human . Ex: Hypophosphatemia:
low levels of inorganic phosphate in the
blood.)
Diagnosis is complicated by the process of
X inactivation in females.
What type of inheritance is This ?
Y-Linked Inheritance
Traits on the Y chromosome are only found in males, never
in females.
The father’s traits are passed to all sons.
Dominance is irrelevant: there is
only 1 copy of each Y-linked gene .
LERI WEIL DYSCHONDROSIS
What type of inheritance is This ?
Mitochondrial Genes
Mitochondria are only inherited from the mother.
If a female has a mitochondrial trait, all of her (male and females ) offspring inherit it.
If a male has a mitochondrial trait, none of his offspring inherit it ; as sperm Head do not have mitochondria. .
Note that only one allele is present in each individual,
so dominance is not an issue.
MULTIFACTORIAL INHERITANCE
Multi-”FACTORIAL”, not just multi-GENIC
“SOIL” theory
Common phenotypic expressions governed by “multifactorial” inheritance
Hair color
Eye color
Skin color
Height
Intelligence
Diabetes, type II
Features of Multifactorial inheritance
Expression determined by NUMBER of genes
Overall chance of transmission is 5% if 1st degreerelatives is affected.
This risk of transmission will increased (>5%) ifmore than one child is affected.
“MULTIFACTORIAL” DISORDERS
Cleft lip, palate
Congenital heart disease
Coronary heart disease
Hypertension
Gout
Diabetes
Pyloric stenosis
MANY, MANY, MANY, MANY MORE
The Punnett square
The Punnett square is a tabular summary of every
possible combination of one maternal allele with one
paternal allele for each gene being studied.
It is named after Reginald C. Punnett, who devised the
approach.
It is used by biologists to determine the probability of an
offspring's having a particular genotype.
The Punnett square
It is used to simulate segregation of alleles into
gametes by meiosis and recombination of new
genotypes fertilization.
It predicts the genotypes and phenotypes of the
offspring of any two parents (when all possible
sperm are given an equal chance to fertilize all
possible eggs).
Summary
Pedigrees are family trees that explain your genetic history.
Pedigrees are used to find out the probability of a child having a disorder in a particular family.
To interpret a pedigree, it is essential to determine - the disease condition is
autosomal or X-linked
And
dominant or recessive.