Genetics
Genes
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Coding: Exons ? 1.5% of Human genome
Non-Coding - INTRONS
Regulation of genes
- Centromeres
- Telomeres
- Trans beans (Jumping genes)
- Non-Coding RNAs
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- Micro RNA - miRNA - 21-30 oligonucleotide
- gene silencing RNA (post-Transcription)
- 15% of human genome
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- exogenous RNA (in vitro)
- To study gene function - knock down technique
- >200 nucleotide.
- associated with Barr-Body formation
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d) lnc-RNA - Noncoding RNA in Human genome
wi-Interacting
Genetic disorders
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Single gene (Mendelian)
Multigene
Classic
Unclassic
-multifactorial inheritance/
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Complex polygenic.
AR
1) gonadal mosaicism
(>2mutant genes + environmental factors)
AD
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XR
1) mitochondrial inheritance
eg- Diabetes
Cleft lip/palate
XD.
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iii) genomic imprinting - Congenital Heart disease.
1) Trinucleotide Repeat - Gout / HTN
-m/c pattern of inheritance - Autosomal dominant (Vertical)
- m/c pattern in inborn error of metabolism - AR - (Horizontal)
AR
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AD
Aa - Carrier
Aa- disease
aa - disease.
aa-disease (die in utero)
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AD
AD
?) Reduced Penetrance,
eg- Retinoblastoma
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ch-13q/14
Ro-Two Hit Hypothesis - Homozygous
Loss of Heterozygosity = LHO. LOH
1st Hit- germline Hit
Knudson's Two Hit
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2nd Hit- acquired Hit
LOH:
AD-PKD
Hirschsprung's disease
Wilm's Tumor
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Retino Blastoma.
11) Dominant Negative effect.
eg Mutant-protein/gene
affecting/ N genes / proteins
MT/C inherited Connective tissue disorder - Marfan's Syndrome
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Fibrillin gene C15q
Revised Ghents Criteria:
1) Family h/o Marfans
ii) Cardinal features
?) Fibrillin gene-Imutation
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M/C Aortic dissection.
1) Ehlers Danlos Syndrome - Rubberman Syndrome.
Hyperextensibility of joints + Skin Hyperextensibility
Collagen m/c collagen-?
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m/c Subtype of EDS-Type-?
? Rupture of colon/arteries - Type ? [Vascular type]
Worse prognosis - Type-?
I/?- Scarring affected. Cigarette paper Like Scarring
3) Osteogenesis imperfecta Collagen-I
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Pedigree analysis-
- x-linked Recessive Carrier - Divorce
-Proband /Index Case - Infertility.
- deceased /dead
- unknowngender
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- emotional attachment.
Hermaphrodite
extramarital affair
- miscarriage/abortion
Adopted child
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- No. of siblings.
-monozygotic.
- Dizygotic
Ledigree analysis
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- Both parents normal,
one/variable, child affected
undassic inheritance
Gonadal mosaicism - Variant of Autosomal dominant
mutation occur in zygote level
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eg. Osteogenesis Imperfecta, Tuberous Sclerosis
Achondroplasia
Mitochondrial inheritance (Maternal inheritance)
ovum - Rich in mitochondria
mtDNA
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Heteroplasmy
Normal
mutant
when mutant allele, normal ? disease cum
Sperms also contain mt-DNA - selectively degraded
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during fertilization
ubiquitin proteasome pathway
diseases through mitochondrial Prter
? Leber's Hereditary optic neuropathy- Prototype
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? NARP. - Neurogenic weakness
Ataxia
Retinitis Pigmentosa
Retinitis pigmentosa m/c/pattern of inheritance
60% Sporadic 40% Hereditary
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(AR(60%) 30-40%. AD Digeni
X-linked Recessive
? x-chromosome of father transmitted to daughter only
mostly males are affected
?Females also affected when Carrier mother + affects father
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Y-chromosome. Y linked Disorders
-only males are affected: Retinitis pigment
Fragile X Syndrome XLR (m/c)
? Hemophilia - A/B-XR Hemophilia-C/t AIR!.
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X Linked dominant
Father
all daughters
Sons spared.
from affected daughters
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Sons Daughters
Alports - 85% X linked Dominant
m/c
Autosomal Recessive-
Affected-0%
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Carrier-50%
Galactosemia AR
Uniparental Disomy - one parent giving both genes.
Not Carrier Normal
mechanism
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Affected-1
imprinting-inactivation
? Functional gene inherited from parent only
Chromosome-15q
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Prader-Willi Angelman
-Obesity -Ataxia
-Hypogonadism -Laughter
Ghrelinexogenic Happy Puppet
m/c i) deletion
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?) uniparental disomy.
maternal Paternal
gene gene Angelman
Prader-Willi
UDPassociations. ?) Angelman
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?) Prader-Willi
?) Russel - Silver
iv) Bloom - Ruare (m/c-AR)
v) Beckwith-Weidman (UPD of WT-11p11
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Sinucleotide Repeat
Codons-normally, Triplets - Repeat normally
Times-29 (6-55)
55-200- Premutation - asymptomatic
>200 Repeats - Disease
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No. of Repeats correlate with severity of disorder.
No. of Repeats Severity
Dynamic mutation - No. of Repeats - gain of mutation
Oogenesis Spermatogenesis
affecting Noncoding Coding areas
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areas- exons
eg-1) Fragile-x-Syndrome 1) Huntington's chorea
2) Friedreich's ataxia 2) Spino Cerebellar ataxia
3) Myotonic Dystrophy
Huntington's Disease Father ? 300 Repeats
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Anticipation Son - Repeats
Severity, (earlier age); Severity.
years- earlier next generation - earlier onset
? X-Chromosome shows fragile site when grown
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on folate deficient medium
Large Testis (macio Orchidism) > NTR [Hallmark]
Large face Small / Normal-nose
mandible
everted ears
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KARYOTYPING
?Study of chromosome
? paired chromosome
length.
Sample-?) Amniotic fluid - shedding of epithelium
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(skin, UGGT, GIT, RCT)
ii) Chorionic villi Biopsy
iii) Fetal tumor Sample. m/c-fetal tumor - Teratoma.
iv) Cordocentesis-umblical Cord Blood
1) Peripheral blood - lymphocyte
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other cells reversed - dont pudifuate
In Test tube
Fixative of choice
Cornoy's Fluid
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Karyotyping - Methanol + glacial acetic acid
3parts + 1part
Histopathology - 10/- neutral buffered Formalin
Colectron microscopy glutaraldehyde Best
Osmium Tetraoxide
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Cytology 95% Cothanol (cytology)-pap Smear
Hematopoietic cells mercuric Chloride - Zanker's fluid
Preic acid - Bouin's fluid Glycogen/Lipid storage
disorders
Testicular biopsy Bouin's fluid-ideal (preserves and
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Routine Karyotyping neutral buffer formalin - universal
Cells
Proliferate in Test
metaphase arrest Colchicine
Resolution - 800 bands/ Haploid set
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To increase Resolution prophase arrest of
Resolution - 1500 bands
Routine Cytogenetic analysis Light micro Reduction 5ml
of chromosome
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P(shat)
P-petit
Types of chromosomes
i) Metacentric p q. Rest all chromosomes metacentric
ii) Sub-MATA centric - X-chromosome
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iii) Acro-centric - Y-chromosome
i) associated with pathogenesis
Down Syndrome - Robertsonian Translocation
t 21 13
14
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All aw Acrocentric chromosomes
Auccentric group - 21/13,14,15, 22/7
iv) Telocentric -not-seen in Humans
normal division vertical
Irto normal axis- Horizontal plane
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Isochromosome (i)
m/c Isochromosome - Xq-xlong arm
m/c in Human Cancer - 17q, (i)
ovary Testis
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917q - m/c cytogenetics in Medulloblastoma
Posprognosis
Uses of Karyotyping
1) Numerical disorders
Jouploid - 23x
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Aneuploidy-odd
m/c Chaomosomal disorder - Trisomy 16 (But die in utero)
m/c chromosoma disorder Down Syndrome
Limitations - ?) microdeletion
?) Amplification cannot be
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(iii) Complex Translocation seen
FISH can overcome this
Best for brown gene FISH - Limitation-Cannot
detect Small genes.
For point mutation - PCR Limitation - Cannot
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detect lager genes.
NTLPA- Multiplex Ligation Associated Probe Amplified
- overcome limitations of both PCR FISH
- Both Small & lauge genes
- Best for Cystic fibrosis detection
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Mech-i) Meiotic-Non-disjunction
95%
trisomies, except for. Edward Syndrome - Meiosis ?
Rocker Bottom feet - more Edward Syndrome
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extrachromosome in Down's Maternal in origin
ii) Robertsonian - 4% No Relation with advanced maternal age
iii) Mosaicism - 1%
Robertsonian Mosaicism
t 21 13,14,15;22. Normal + abnormal no. of
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t (21;21) -100% chance stransit-chromosomes.
of 2nd Baby
ALL- m/c leukemia associated with Down's
ANTLITY - Acute Megabaujocytic. m/c leukemia in children
>40 years - Alzheimer's -100/
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<3 years.
m/c Cardiac defect - endocardial cushion defect >VSD >ASD
Turner's Syndrome ?) 45 XO m/c
?) 46 X(Y) (Ring chromosome)
iii) 46 EXP
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ovarian Tissue
Histology Breast Tissue, Normal
m/c Cardiac. Bicuspid aortic valve
Tumors 9) Colon Ca AML - Downs
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?) AML. Tunes
Klinefelter Syndrome.
Trisomies. 22x and ly
47xxy -meiotic nondisjunction (meiotic 7
Associated with both Advanced Maternal Paternalay
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Testosterone ; 17SH, oestrogen.
gynaecomastia
m/c Cancer Breast Cancer
m/c germ cell tumor - Extragonadal > gonadal
Teratoma
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m/c site -m edrastimum
m/c Site EGCT in Brain - pineal gland
variation among individuals
15-million Base pairs
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- polymorphic genes /mauku genes can detect
multifactorial Junknown gene mutation,
1) always dose to disease causing allele.
?) disease
Polymorphic genes always stably transmitted to next generation.
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Linkage - Disequilibrium
motype of polymorphic gene - SNP-Single nucleotide Polymorph
- inucleotide difference /1000 base pairs
?) Repeat length polymorphism
a) microsatellite Madosaledlite
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Q(2-6) Base 15-70 Base Q
Pair repeats. Pair repeats
Uses
Single gene
multifactorial
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Direct Sequencing Polymorphic genes
with PCR/FISH -Indirect Sequencing
study of polymorphic gene
for a disease in family
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Large Population : GIWAS (genome wide Analytical Study)
To detect Same chromosome - Tumor gene/Normal gene
T gene Normal gene
Patient Control (entire chromosome)
gene
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Fluorochrome. Red Green
Hybridization
Fluorochrome Red Signal-Duplication (guin)
Scanner Green Signal - Deletion (Loss)
Computer Normal chromosome - Yellow/Black
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Yellow/Black. NTPoroarray Analysis
NTPoro Array based Comparative, genomic
Hybridization CGH
Breast Cancer
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ERT; PRtve; Her. neu
- gene expression profiling
- molecular classification of Cancer
? Molecular classification of Breast Ca based on gene
expression profiling
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FISH Congenital malformation-metaphase
Oncological Specimens. Inbsphase chromosome)
2 variants) 1) Chromosomal painting Centire human genome
on same chromosome) Hist
fluorochrome pointed on entire genome of
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one chromosome
2) Multicoloured FISH: entire genome on all gen chromosome
Spectral Karyotyping, simultaneously
Spectacularly to fluorochromes Computer generalized
Immunology
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Immunity
Innate Acquired
- Birth/1st line of defence -memory
-Nomemory -Specific
-Non-Specific
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This download link is referred from the post: NEET PG Last 15 Years 2012-2025 Previous Question Papers with Answers (Solved Question Papers)
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