What is it? And Classification Genetic Syndrome
Its effect on animal reproduction and Production Effects on Animal Breeding
Detection of Chromosomal Abnormality Detection of chromosomal abnormality
Genetic SyndromeSyndrome- set of signs and symptoms
characterized by malformations or malfunctions in any of the body’s systems
3 Groups of genetic diseases
1. Disorders with multifactorial inheritance (polygenic)
2. Monogenic (mendelian) disorders
3. Chromosomal aberrations
How abnormality happen?Typically occur when there is an error in cell
division following meiosis or mitosisMistake in egg cell or sperm
Anomaly present in every cell of body
Some anomaly after conceptionMosaicism
Disorders with multifactorial inheritance (polygenic)influence of multiple genes +
environmental factorsrelatively frequentEx.
Diabetes mellitus Hypertension Gout Schizophrenia Congenital heart disease - certain forms Some types of cancer (ovarian, breast, colon)
Monogenic (mendelian) disorders
mutation of 1 gene, mendelian type of inheritances
1. Autosomal dominant
2. Autosomal recessive
3. X-linked
Autosomal dominant disordersboth homozygotes and heterozygotes are
affected
usually heterozygotes (inherited from one parent)
both males and females are affected
transmission from one generation to the other
50% of children are affected
Ex.
Familial hypercholesterolemia Marfan syndrome Ehlers-Danlos syndrome
Autosomal recessiveonly homozygotes are affected, heterozygotes
(parents) are only carriers
25% of descendants are affected
if the mutant gene occurs with low frequency - high
probability in consanguineous marriagesonset of symptoms often in childhood
frequently enzymatic defect
testing of parents and amnial cells
Ex.
Cystic fibrosis Phenylketonuria (PKU) Galactosemia Glycogen storage diseases (glycogenoses) Lysosomal storage diseases Gaucher disease
X-linked diseasestransmitted by heterozygous mother to sons
daughters - 50% carriers, 50% healthy
sons - 50% diseased, 50% healthy
Children of diseased father - sons are healthy, all daughters are carriers
Hemophilia A (defect of Factor VIII) Hemophilia B (defect of Factor IX) Muscle dystrophy (Duchen disease)
Types of Chromosomal aberrations
Numerical AbnormalityNormal- Two copies (2n) of the same
genome in somatic cell
Aberration- deviation from diploid (2n )
Types
Aneuploidy
Term Chromosomes DescriptionAneuploidy 2n+/- few One or few chromosome extra or
missingTrisomy 2n+1 One extra chromosomeDouble trisomy
2n+1+1 Two non-homologous chromosome extra
Tetrasomic 2n+2 One chromosome pair extraMonosomic 2n-1 One chromosome missingDouble monosomic
2n-1-1 Two non-homologous chromosome missing
Nullisomy 2n-2 One pair of homologous chromosome missing
Syndrome
Karyotype Main clinical features
Down Trisomy 21 Short, broad hands with single palmar crease, decreased muscle tone, mentalretardation, broad head with characteristic features, open mouth with large tongue,up-slanting eyes
Edwards Trisomy 18 Multiple congenital malformations of many organs, low-set malformed ears, recedingmandible, small eyes, mouth and nose with general elfin appearance, severe mentaldeficiency, congenital heart defects, horseshoe or double kidney, short sternum,posterior heel prominence
Patau Trisomy 13 Severe mental deficiency, small eyes, cleft lip and/or palate, extra fingers and toes,cardiac anomalies, midline brain anomalies, genitourinary abnormalities
Turner 45,X Female with retarded sexual development, usually sterile, short stature, webbing of skinin neck region, cardiovascular abnormalities, hearing impairment, normal intelligence
Klinefelter
47,XXY Male, infertile with small testes, may have some breast development, tall, mild mentaldeficiency, long limbs, at risk for educational problems
Triple X 47,XXX Female with normal genitalia and fertility, at risk for educational and emotionalproblems, early menopause
XYY 47,XYY Tall male with normal physical/sexual development, normal intelligence, increasedtendency for behavioural and psychological problems
EuploidyTerm Chromosom
eDescription
EuploidMonoploid X Only one genome presentHaploid n Gametic chromosome number of the
concerned species presentPolyploid More than two copies of genomeAutopolyploid More than two copies of the same
genome presentAutotriploid 3X Three copies of the same genome
presentAutotetraploid
4X Four copies of the same genome present
Allopolyploid Two or more distinct genome; generally each genome has two copies
allotetraploid 2X1+2X2 Two distinct genomes; generally each genome has two copies
Structural abnormality
Chromosome BreakageCause – not definitely knownPossible factor-cosmic radiation, nutritional
deficiency, environmental condition
type
Deficiency or deletion
Loss of chromosome segment
Loss of chromosome segment has a deleterious effect and larger deletion may be lethal
Ex. Cri du chat syndrome
Cry of the cat in French deletion of short arm of chromosome 5 Baby make high pitch cries Wide set eyes, small head and jaw, mentally retarded
Duplication or Repeat(presence of additional chromosome segment)
Not produce as drastic effect as deletion in term of phenotype and survival
Syndrome Chromosome region duplicated
Main clinical features
Beckwith–Wiedemann
11p15.5 Large tongue, tissue and organ overgrowth, mild mental retardation
Charcot–Marie–Toothdisease type 1A
17p11.2-p12 Decreased reflexes, progressive distal muscular wasting, decreasedmuscle tone, sensory neuropathy
Cat-eye 22pter-q11.2 Eye defects, absence of anal opening, skin tags in front of ears,characteristic facies, renal, skeletal and genital anomalies, mentalretardation
Inversion
Inversion suppresses genetic recombinations.
Helpful in maintaining hetrogygosity and balanced lethal system
The most common inversion seen in humans is on chromosome 9, at inv(9)(p12q13)
Translocation(a segment from one chromosome is detached and
reattached to a different – non homologous
chromosome)Gene from one chromosome is transferred to
another
Simple Translocation - One sided translocation
Reciprocal Translocation- mutual exchange of segment
Ring FormationA portion of a chromosome has broken off
and form a circle or ringCan happen with or without loss of genetic
material
Detection of chromosomal abnormalityBy Karyotyping Chromosome Banding- G, Q, C, R banding
etc.FISH (fluorescent in situ hybridization)Comparative genome hybridization (CGH)SNP (single nucleotide polymorphism)
microarraysComparative genome hybridization (CGH)
Effects on Animal Breeding
Disorder of sex development (DSD)
Impaired fertililty
Disorder of sex development cytogenetic analysis focuses on the
identification of sex chromosomesXX/XY chimerism-
Freemartinism, observed in females originating from heterosexual pregnancies, Infertile
Sex chromosome aneuploidiesdeleterious effects on sex developmentsterility
Mutation The most common clinical features
Effects on fertility
Decreasing incidence in different species
X monosomy
Usually normal external genitalia; abnormal oestrus or no clinical signs of oestrus; small or hypoplastic ovaries
Sterility Horse > cat and dog > cattle and pig
XXX trisomy
Normal external genitalia; usually lack of clinical signs, sometimes irregular oestrus
Infertility Dog, horse
XXY trisomy
Small and hypoplastic testes; abnormal spermatogenesis (oligospermia or azoospermia)
Sterility Cat and cattle > dog and horse > pig
XYY trisomy Usually normal phenotype; small testes
Infertility Cattle
Decreased fertility in carriers of balanced chromosome aberrations
Balanced structural rearrangements Robertsonian translocation ,tandem fusions, reciprocal translocations inversions
are inheritable mutationsNo visible alteration of sex development
Genetically abnormal animalsGenetically abnormal animals
Partial Hypotrichosis Complete Hypotrichosis
congenital alopecia and anaemia presence of marked wrinkling of the skin
AIChromosomally abnormal bull
Use of chromosomally
abnormal semenInfertility, repeat breeding, genetic
disorder
Huge disaster
Dead and live sperm, sperm motility, semen
volume
SolutionGenetic
testing of animal
MATING WITHOUT TESTING
NS WITH CARRIER BULL
AFTER GENETIC TESTING
AFETR GENETIC TESTINGAFETR GENETIC TESTING
GENETICALLY CLEAN POPULATION
Consequences
BLAD (Bovine Leukocyte Adhesion Deficiency). It was estimated that 16,000 calves were born with BLAD each year. Hence, the average economic loss per calf was roughly 300 US dollors.
Prevalence of BLAD in Indian HF crossbred cattle population is an alarming situation due to consistent reports from 1999 to 2013.
Factor XI deficiency (FXID) is responsible for repeat breeding in carriers leading to the financial losses . In Turkey (Akyuz et al., 2012) reported an extra $ 324 financial loss compared with a normally fertile cow due to this syndrome.
CVM ( Complex Vertebral Malformation ) carriers in India and worldwide much more higher than other four disorders i.e. BLAD, DUMPS, Citrullinemia and Factor XI
In 2012 in New Zealand Livestock Improvement Corporation (LIC) , a farmer cooperative that sells bull semen was been warned for supplying defective semen to farmers who produced 1500 defective calves with genetic defect leading to excessive hairiness and intolerance to heat ultimately reducing milk producing ability.
1;29 CFT in Jersey cross cow in Chennai (Thiagarajan et al., 1990)1;29 CFT in Jersey cross bull in MS used through AI for 9 years (Chauhan
et al.2009) 7;16 CFT in HF cross bull under use through AI in KDC Mumbai
( Biotech lab report 1999-2000)7;16 CFT in HF cross bull before use through AI in MS (Patel,1999)1;9 CFTs in Gir bull in Gujarat State ( Paderi et al., 2011b)16;20 CFT in Deoni bull calf in 16;20 in Karanataka State ( Paderi et al.,
2011a)8;29 CFT in one Gaolao Bull and it’s 12 progeny in MS ( Umrikar et al.,
2013)
CFT- Centric Fusion Translocation (Robertsonian Translocation)
References https://www.britannica.com/science/chromosomal-disorderhttps://www.genome.gov/11508982/Gene VGenetic by Dr Vijay KumarChromosome Abnormalities in Domestic Animals as Causes of
Disorders of Sex Development or Impaired Fertility http://dx.doi.org/10.5772/62053
Gholap P.N., Genetic Diseases in Cattle: A Review, Research Journal of Animal, Veterinary and Fishery Sciences Vol. 2(2), 24-33, February (2014)
Arcangelo Gentile, Inherited disorder of Cattle; A selected review, Slov Vet Res 2006;43(1)17-29
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