Genetics

1. Patient with B thalassemia major has what type of mutation?

*Non-sense>Premature termination of protein synthesis>No Bglobin chain thus HemA(a2B2) is decreased>Increase in Hem A2(a2D2) and HemF(A2Y2)

Frameshift mutation > Insertion or deletion of nucleotides leading to altered reading frame > Abnormal HemA(a2B2) production

Missense mutation > Alteration in amino acid sequence of Bglobin chain > HemA(a2B2) is abnormal

Silent mutation > No change in amino acid sequence of Bglobin chain > Normal HemA(a2B2) production

B thalassemia major is characterized by mutations that result in reduced or absent production of the Bglobin chain. This leads to a decrease in HemA(a2B2) and an increase in HemA2(a2D2) and HemF(A2Y2) chains.

Explanation

B thalassemia major is characterized by mutations that result in reduced or absent production of the Bglobin chain. This leads to a decrease in HemA(a2B2) and an increase in HemA2(a2D2) and HemF(A2Y2) chains.

2. Patient with Sickle cell trait has what type of missense mutation?

Nonsense mutation

Frameshift mutation

*Don't get all wet if you see Glutamic acid substitution by Valine as this is RESULT of Missense(Point mutation that changes amino acid) mutation which involves Adenine Substitution by Thymidine.

Silent mutation

Missense mutation results in a single amino acid change in the protein sequence, while frameshift mutation involves insertion or deletion of nucleotides, silent mutation does not result in amino acid change, and nonsense mutation leads to premature termination of protein synthesis.

Explanation

Missense mutation results in a single amino acid change in the protein sequence, while frameshift mutation involves insertion or deletion of nucleotides, silent mutation does not result in amino acid change, and nonsense mutation leads to premature termination of protein synthesis.

3. Between CAG(Ch4) and CGG(Xchr), which one is amplified in spermatogenesis and which one is amplified in Oogenesis?

CAG and CGG both are amplified during Spermatogenesis

CAG is amplified during Oogenesis and CGG is amplified during Spermatogenesis

*CGG is amplificated during Oogenesis(X-linked dominant disorder called Fragile X syndrome-Macroorchidism+Mental retardation)*CAG amplification happens during Spermatogenesis(Huntigton's disease -Autosomal Dominant disease>Caudate nucleus atrophy on MRI)*Number of triplet repeats is of prognostic value and increase in triplet numbers>Worse prognosis(Anticipation-increase in number of triplets>earlier onset of more severe symptoms with each generation)

CAG is amplified during both Spermatogenesis and Oogenesis

CGG is amplified during both Spermatogenesis and Oogenesis

In spermatogenesis, CAG amplification occurs in the context of Huntington's disease, while CGG amplification occurs in Oogenesis leading to Fragile X syndrome. The incorrect answers provided do not accurately reflect the specific amplification patterns observed in these processes.

Explanation

In spermatogenesis, CAG amplification occurs in the context of Huntington's disease, while CGG amplification occurs in Oogenesis leading to Fragile X syndrome. The incorrect answers provided do not accurately reflect the specific amplification patterns observed in these processes.

4. Which genetic disorder is associated with increased CTG repeats on chromosome 19 and can lead to death due to arrhythmia, baldness, testicular atrophy, and sustained grip?

Huntington's disease

Friedreich ataxia

*CTG repeat on chromosome 19>Myotonic dystrophy(AD)>can die from arythmia,this disease loves to destroy Type1 fibers+likes to make you bald+Testicular atrophy+They have sustained grip(Remember they Sustain their grip till their balls atrophy-I KNOW IM LAME but it helps)*GAA repeat on chromosome 9 >Friedreich ataxia<Likely to die from Hypertrophic cardiomyopathy(Which is normally due to mutation in Bmyosin heavy chain that has AD inheritance but here Friedreich ataxia has AR inheritance, but here problem is in mitochondria due to repeats in frataxin gene>Less frataxin-remember Noncoding regions=INtrons are amplified>Less protein snthesis(Other examples of NONcoding region=intron amplification>less protein are Myotonic dystrophy,FXS)*CAG repeat involves amplificationin EXons(Coding regions) that code for Glutamine residues>Polyglutamine disorders(HD and Spinocerebellar ataxia<Also can be caused by Intron amplification in Friedreich's ataxia)

Down syndrome

The correct answer is Myotonic dystrophy, as it is characterized by CTG repeat expansion on chromosome 19 leading to the mentioned symptoms.

Explanation

The correct answer is Myotonic dystrophy, as it is characterized by CTG repeat expansion on chromosome 19 leading to the mentioned symptoms.

5. What is the mechanism of hereditary angioedema and what is its inheritance?

*C1 esterase inhibitor deficiency but everyone knows that so remember that is is inherited in Autosomal Dominant pattern.

C4 esterase inhibitor deficiency; Autosomal Recessive inheritance

ACE inhibitor deficiency; X-linked inheritance

Factor XII deficiency; Autosomal Dominant inheritance

Hereditary angioedema is caused by C1 esterase inhibitor deficiency and is inherited in an Autosomal Dominant pattern.

Explanation

Hereditary angioedema is caused by C1 esterase inhibitor deficiency and is inherited in an Autosomal Dominant pattern.

6. How can you calculate prevalence of autosomal recessive condition in a population if the carrier state is 1/100?

Prevalence=Chance of having Child with AR condition X Number of couples at risk (1/2 X 1/10000 = 1/20000)

*Note as disease is AR you also know Chance of having child with AR condition(1/4)Prevalence=Chance of having Child with AR conditionXNumber of couples at risk(if carrier state is 1/100 that couples at risk are 1/10000 because both of them should be carriers)=1/4 X 1/10000*Thus If you knew prevalence you could divide it by 4 to get Number of couples at risk.*Square root from number of couples at risk would give you information about carrier state.(Remember we squared chance of being carrier to get the number of couples at risk)

Prevalence=Chance of having Child with AR condition X Number of couples at risk (1/4 X 1/5000 = 1/20000)

Prevalence=Chance of having Child with AR condition X Number of couples at risk (1/8 X 1/10000 = 1/80000)

7. In a disorder where you avoid lactose (Galactose + Glucose) to prevent CNS and liver damage (Cirrhosis), you have deficiency of which enzyme and what type of inheritance does it have?

*GALT is deficient so GALT can't take Galactose 1 p and give you UDP galactose.(So Galactose 1 p Increases while Glucose 1 p decreases because UDP galactose is not made )*For now remember that inheritance is Autosomal recessive(Enzyme deficiencies are mostly AR)*Osmotic damage to lens is due to Galactitol accumulation which drives fluid into it.*Increased risk of Neonatal Sepsis due to decreased leukocyte bactericidal effect.

Glucose-6-phosphatase is deficient and the inheritance is X-linked recessive.

Lactase is deficient and the inheritance is autosomal dominant.

Amylase is deficient and the inheritance is codominant or incomplete dominance.

GALT deficiency leads to the inability to convert galactose-1-phosphate to UDP-galactose, resulting in increased galactose-1-phosphate and decreased glucose levels. The disorder is inherited in an autosomal recessive manner, meaning that both copies of the gene must be mutated for the condition to be present.

Explanation

GALT deficiency leads to the inability to convert galactose-1-phosphate to UDP-galactose, resulting in increased galactose-1-phosphate and decreased glucose levels. The disorder is inherited in an autosomal recessive manner, meaning that both copies of the gene must be mutated for the condition to be present.

8. In a patient with degenerative arthritis and black cartilage in joints/intervertebral discs due to a lack of Homogentisate Oxidase, would you expect Maleylacetoacetate to be increased or decreased?

Increased

Unchanged

*Maleyacetoacetate is actually Decreased because Homogentisatte oxidase is lacking(AR) which now can't metabolize Homogentisate to maleyacetoacetate(Too much HOMOGENTISATE is responsible for black discolorations and degenerative arthritis.*Homogentisate Oxidase deficiency>Alkaptonuria which is Autosomal recessive condition(This is what our patient has).*Homogenistic acid oxidation when exposed to light>Pigmentation of urine

Fluctuating

Homogentisate Oxidase deficiency leads to a decrease in Maleylacetoacetate levels, resulting in the black discolorations seen in degenerative arthritis. Alkaptonuria is an autosomal recessive condition caused by this deficiency.

Explanation

Homogentisate Oxidase deficiency leads to a decrease in Maleylacetoacetate levels, resulting in the black discolorations seen in degenerative arthritis. Alkaptonuria is an autosomal recessive condition caused by this deficiency.

9. Why do patients with AR condition (Hereditary fructose intolerance) commonly have Cirrhosis and HYPOphosphatemia?

AR condition causes excessive production of glucose leading to liver dysfunction

*Cirrhosis is due to accumulation of Fructose 1 phopshate(Aldolase B is deficient in this AR condition so you can't convert Fructose1P>G3pand DHAP=Hypoglycemia due to lack of gluconeogenic sybstate while Fructose 1p accumulates >Used up phosphate >Hypophosphatemia)Remember to not give Honey(Fructose) and Sucrose(Glucose+Fructose).FOR NOW at least remember it is Autosomal Recessive(remember enzyme def. is most likely AR)

Due to excessive intake of sucrose and glucose which may lead to liver damage

Inadequate intake of fructose leads to liver impairment and low phosphate levels

The correct answer explains that the accumulation of Fructose 1 phosphate due to Aldolase B deficiency causes cirrhosis and hypophosphatemia in patients with Hereditary fructose intolerance. Avoiding honey and sucrose helps manage the condition.

Explanation

The correct answer explains that the accumulation of Fructose 1 phosphate due to Aldolase B deficiency causes cirrhosis and hypophosphatemia in patients with Hereditary fructose intolerance. Avoiding honey and sucrose helps manage the condition.

10. Baby has Sweet-smelling urine, Mental retardation, Seizures what type of inheritance does this disease have?

Autosomal dominant (PKU)

X-linked recessive (Lesch-Nyhan syndrome)

Mitochondrial inheritance (Leigh syndrome)

*Autosomal recessive(Maple Syrup urine disease)*Lack of Branched chain a-ketoacid deh. >Accumulation of Isoleucine,Leucine,ValineJust remember these 3 they might throw AcCoa,Succinyl CoA or something but remember they are likely to be decreased if you understand why that is awesome and that is more of biochemistry but if you can't your best shot would be that everything except these 3 AA's will be decreased.*we will repeat all these diseases in Biochemistry

This question is related to Maple Syrup urine disease, which is an autosomal recessive disorder caused by a lack of Branched chain a-ketoacid dehydrogenase. The key feature includes the sweet-smelling urine, mental retardation, and seizures due to the accumulation of Isoleucine, Leucine, and Valine. While the incorrect answers refer to different genetic inheritance patterns resulting in other metabolic disorders with distinct characteristics.

Explanation

This question is related to Maple Syrup urine disease, which is an autosomal recessive disorder caused by a lack of Branched chain a-ketoacid dehydrogenase. The key feature includes the sweet-smelling urine, mental retardation, and seizures due to the accumulation of Isoleucine, Leucine, and Valine. While the incorrect answers refer to different genetic inheritance patterns resulting in other metabolic disorders with distinct characteristics.

11. How do you differentiate between Phenylketonuria and Malignant Phenylketonuria and how are they inherited?

Both are X-linked recessive and share the same enzyme deficiency.

*BOTH of them are Autosomal recessive but different enzymes are lacking*In Phenylketonuria you lack Phenylalaninehydroxylase>increased phenylalanine+Decreased tyrosine but in Malignant phenylketonuria u lack Dihydropteritin Reducase needed for BH4 synthesis which is needed for Tryptophan and tyrosine metabolism to Serotonin and Dopamine respectively.You are lucky if they ask you inheritance because both of them are AR.*If Restriction in phenylalanine doesn't help with symptoms it is likely Malignant Phenylketonuria.(You need to give BH4+Ldopa+5 hydroxytryptophan)*Remember PHenylacids are responsible for mousy odor and decrease in tyrosine is responsible for decreased pigmentation in Phenylketonuria(Melanin comes from it)*Excess Phenylalanine is responsible for mental rtardation

Phenylketonuria is Autosomal dominant while Malignant Phenylketonuria is Autosomal recessive.

Phenylketonuria lacks Dihydropteritin Reductase and Malignant Phenylketonuria lacks Phenylalaninehydroxylase.

12. Which Glycogen storage disease are of Autosomal recessive Inheritance?

Wilson disease - Autosomal recessive disorder characterized by defective hepatic copper transport resulting in copper accumulation in various tissues.

Marfan syndrome - An autosomal dominant disorder that affects the connective tissue leading to abnormalities in the skeletal system, cardiovascular system, eyes, and skin.

Fabry disease - X-linked recessive disorder resulting in a deficiency of alpha-galactosidase A leading to the accumulation of globotriaosylceramide in multiple tissues.

*McArdle disease(Type5)-Glycogen phosphorylase lack>Rhabdomyolisis with myoglobinuria with NO lactic acid increase with excercise(Lack of glucose because glycogen can't be posphorylated>too much glycogen in muscle)*Pompe Disease(Type 2)-Alpha1,4 glucosidase=Acid maltase(LYSOSOMAL ENZYME) >Increased glycogen and Cardiomegaly, most likely cause of death:RESTRICTIVE cardiomyopathy.*Von Gierke(type1)-Too much Glucose6phosphate due to lack of Glucose6phosphatASE so less g6p is converted to glucose(So Fasting hypoglycemia with Enlarged KIDNEY and Liver as both are involved in gluconecogenesis)*Cori disease(type3)-Debranching eznyme(1,6glucosidase def)<too much glycogen,Limit dextrins in cytosol.EY FOR NOW AT LEAST KNOW That they are AR, we will go into details with biochem.

13. Baby fails to develop social smile you see galactose in urine and in blood, baby also has cataracts (Due to Galactitol), what is the inheritance?

Autosomal dominant

X-linked dominant

Mitochondrial inheritance

*Autosomal recessive lack of Galactokinase(can't convert galactose to galactose 1p)even if you weren't sure if it was this or Galactosemia(Lack of GALT) answer would still be Aurosomal recessive :)) as GALT(can't convert G1p>UDB glucose) deficiency is also inherited in Autosomal recessive fation.

The correct inheritance pattern for the described condition is autosomal recessive as explained in the answer section.

Explanation

The correct inheritance pattern for the described condition is autosomal recessive as explained in the answer section.

14. Which inheritance pattern is associated with decreased affinity of Cystathionine synthase for B6, Methionine Synthase deficiency, and Cystathionine deficiency, all leading to homocystinuria with marfanoid habitus?

Autosomal dominant

*Autosomal recessive fation these all can cause homocystinuria- Patietns have marfanoid habitus which is example of Genetic heterogenneity.

X-linked recessive

Mitochondrial inheritance

These genetic conditions are inherited in an autosomal recessive manner, meaning that both copies of the gene must be mutated to manifest the disease.

Explanation

These genetic conditions are inherited in an autosomal recessive manner, meaning that both copies of the gene must be mutated to manifest the disease.

15. New mutations that are acquired with AD disorders are maternally/paternally inherited?

Inherited equally from both parents with a 50/50 chance.

Randomly inherited with no specific parental pattern.

Maternally inherited due to mutations in somatic cells.

*Paternally inherited due to mutations in GERM cells of oler males.*Normally Homozygtoes are spontaneously aborted, so chances of having child for AaxAa are 50/50 in most cases but if Homozygotes(AA) survive than 3/4 will be affected.*MALE TO MALE TRANSMISSION=AUTOSOMAL DOMINANT(That's how you differ AD form XlinkedDominant disease where there is no male-male transmission)*MC AD disease is Von Willebrand Disease(Decreased factor 8+Increased bleeding time with normal platelet count and Increased PTT)

In AD disorders, new mutations are mostly paternally inherited due to mutations in GERM cells of older males, rather than being maternally inherited or randomly inherited. Inheriting AD disorders equally from both parents with a 50/50 chance is not characteristic of the mode of inheritance for these disorders.

Explanation

In AD disorders, new mutations are mostly paternally inherited due to mutations in GERM cells of older males, rather than being maternally inherited or randomly inherited. Inheriting AD disorders equally from both parents with a 50/50 chance is not characteristic of the mode of inheritance for these disorders.

16. Female with Hirsutism(Shunting of 17hp to DHEA)+Hyperkalemia(Lack od aldosteorne),Hypotension(lack of cortisol+aldosteorne),INcreased17hydroxyprogesterone(can't hydrolyze it to 11DOC or 11 deoxycortisol),increased renin(Less feedback inhibition) what is inheritance?

Patient has 21 hydroxylase deficiency - Autosomal dominant inheritance.

Patient has 21 hydroxylase deficiency - X-linked recessive inheritance.

Patient has 21 hydroxylase deficiency - Mitochondrial inheritance.

*Patient has 21 hydroxylase deficiency -Autosomal recessive inheritance just like Wilson disease and Hemochromatosis.*Most common AR disease is Hemochromatosis

The correct answer is that patient has 21 hydroxylase deficiency which is inherited in an autosomal recessive manner. This condition is characterized by the symptoms mentioned in the question such as hirsutism, hyperkalemia, hypotension, and increased renin levels.

Explanation

The correct answer is that patient has 21 hydroxylase deficiency which is inherited in an autosomal recessive manner. This condition is characterized by the symptoms mentioned in the question such as hirsutism, hyperkalemia, hypotension, and increased renin levels.

17. Marfan syndrome usually involves a MISSSENSE mutation on chr. 15. What is its penetrance?

VARIABLE penetrance

HIGHLY penetrant

*INCOMPLETE penetrance so yea they can be phenotipically normal while Familial Polyposis(Chr5) has COMPLETE penetrance(100% will express the phenotype)

COMPLETE penetrance

Marfan syndrome is known for having an INCOMPLETE penetrance, meaning that individuals can be phenotypically normal despite carrying the mutation. This is different from Familial Polyposis on Chr. 5, which has COMPLETE penetrance where all individuals with the mutation will express the phenotype.

Explanation

Marfan syndrome is known for having an INCOMPLETE penetrance, meaning that individuals can be phenotypically normal despite carrying the mutation. This is different from Familial Polyposis on Chr. 5, which has COMPLETE penetrance where all individuals with the mutation will express the phenotype.

18. What is the most common mendelian disorder causing mental retardation?

*Fragile X which is Xlinked DOMINANT(Not recessive) disorder that involves (CGG repeat)>Constriction at the long arm of Cr.X(hence fragile) this is region where FMR1 gene is located and this leads to Loss of function of FMR1 which is nornally expressed in Brain>Mental retardation.(Normally FMR1 is TRANSLATION modulator that REDUCES protein synthesis at synaptic junctions).*Moms with premutation can have Increased risk of Premature ovarian failure(Can have mental retardation too-but they LOVE to ask about premature ovarian failure)*Remember generally females can express this disease too with Mental retardation+Premature ovarian failure but Mental retardation is less severe due to random X chromsome inactivation in females.*Very characteristic finding in males is Macroorchidism(Big balls basically lol when they hit puberty)+Long face with large mandible and everted ears.*Diagnose By PCR(DNA analysis)<If it fails you can do Southern DNA.

Klinefelter syndrome

Turner syndrome

Down syndrome

Fragile X syndrome is the correct answer as it is an X-linked dominant disorder caused by a CGG repeat on the FMR1 gene, leading to mental retardation. Down syndrome is actually the overall most common cause of mental retardation, but it is not a mendelian disorder. Turner syndrome and Klinefelter syndrome are not typically associated with mental retardation.

Explanation

Fragile X syndrome is the correct answer as it is an X-linked dominant disorder caused by a CGG repeat on the FMR1 gene, leading to mental retardation. Down syndrome is actually the overall most common cause of mental retardation, but it is not a mendelian disorder. Turner syndrome and Klinefelter syndrome are not typically associated with mental retardation.

19. What is the mechanism and inheritance of Vitamin D resistant rickets?

Autosomal recessive inheritance affecting the vitamin D metabolism resulting in poor bone mineralization

Multifactorial inheritance involving both vitamin D and calcium uptake leading to defective bone development

Heredity pattern unknown, leading to low calcium absorption and bone weakness

*Xlinked DOMINANT(no male-to-male transmission) defect in Renal and GI REabsorbtion of Phosphate>Hypophosphatemia>Can't drive calcium into bone due to low Phosphate thus>Osteomalacia=defective bone mineralization.

Vitamin D resistant rickets is specifically linked to an X-linked dominant defect in phosphate reabsorption, differentiating it from the other inheritance patterns and mechanisms mentioned.

Explanation

Vitamin D resistant rickets is specifically linked to an X-linked dominant defect in phosphate reabsorption, differentiating it from the other inheritance patterns and mechanisms mentioned.

20. When does nondisjunction result in mosaicism, with an example frequently tested?

Nondisjunction of chromosomes in MEIOSIS during late embryonic period

Nondisjunction of chromosomes in MEIOSIS during early embryonic period

Nondisjunction of chromosomes in MITOSIS during late embryonic period

*NONdisjunction of chromosomes in MITOSIS during early embryonic period>2 different lines of cells from 1 zygote.<results in mosaicism*Don't confuse this with Nondisjunction-Unequeal separation of chromosomes in MEIOSIS(COMPLETE Monosomies,Trisomies like Complete Turner's,Down's)
*Note MOST SURVIVED = Born patients with Turner syndrome (Thus MC GENOTYPE)will have MOSAICISM>With MC genotype of 45x,46xx,however overall most likely phenotype is 45x, as mosaics are more likely to survive so if you are tested the defect was most likely-NONdisunction during mITosis.<While if they are genotypically 45X(No mosaicism) than nondisjunction likely happened during mEiosis.(remember complEte mEiosis)

Nondisjunction leading to mosaicism occurs when chromosomes fail to separate correctly during mitosis, resulting in multiple cell lines from a single zygote. Turner syndrome is a commonly tested example where mosaicism is common due to the survival advantage. Nondisjunction during meiosis can lead to complete monosomies or trisomies, but the focus here is on mitotic non-disjunction for mosaicism.

Explanation

Nondisjunction leading to mosaicism occurs when chromosomes fail to separate correctly during mitosis, resulting in multiple cell lines from a single zygote. Turner syndrome is a commonly tested example where mosaicism is common due to the survival advantage. Nondisjunction during meiosis can lead to complete monosomies or trisomies, but the focus here is on mitotic non-disjunction for mosaicism.

21. What is Robertsonian translocation and why does it matter?

*Everyone knows that most cases of down's sydnrome are caused by nondisjunction in meiosis but so they will ask about mechanism of rare cases caused by Robertsonian tanslocation.*Firstly translocation is Transfer of parts betweenNONhomologous chromosomes(Don't confuse this with Homologous recombination in prophase of meiosis 1)*Now robertsonian translocation is BALANCED translocation(Balanced means that translocated fragment is Functional) between Acrocentric chromosomes(Centromere is near the end of chromosomes)*They will ask EXACT translocation which is between LONG arms of 14 and 21 and yes that matters as short arms combine too but are lost with divisions, due to presence of extra 14:21 with normal 21 from mother and 21 from father you get 3 functional 21 chromosomes >Trisomy 21(Second most common cause of this trisomy thus second most common mechanism of MOST common cause of Mental retardation, mostly down's sydnrome is due to Nondisjunction and lastly it is less than 1 % of cases which are mosaics)

Robertsonian translocation involves a translocation between the short arms of acrocentric chromosomes.

Trisomy 21 is mainly caused by nondisjunction during meiosis.

Translocation is the movement of parts between homologous chromosomes.

22. What is the most common cause of Floppy baby syndrome?

Advanced paternal age

*Nondisjunction inf Maternal Meiosis 1(In other words Down's syndrome is most common cause) so N1 risk factor is not honey with botulinum toxin or Prader-willi syndrome but is Advanced maternal age(as Aged ova Increases Risk of Down's sydnrome and other trisomies)But they will give you other clues like Simian crease,Flat facial profile, prominent Epicanthic folds.

Prader-Willi syndrome

Honey contaminated with botulinum toxin

The correct answer is Nondisjunction in Maternal Meiosis 1, which leads to Down's syndrome being the most common cause of Floppy baby syndrome. Honey contaminated with botulinum toxin and Prader-Willi syndrome are not major risk factors for this syndrome. Advanced maternal age, which increases the risk of Down's syndrome and other trisomies, is the key factor to consider.

Explanation

The correct answer is Nondisjunction in Maternal Meiosis 1, which leads to Down's syndrome being the most common cause of Floppy baby syndrome. Honey contaminated with botulinum toxin and Prader-Willi syndrome are not major risk factors for this syndrome. Advanced maternal age, which increases the risk of Down's syndrome and other trisomies, is the key factor to consider.

23. Why would a patient with Down's syndrome be vomiting bile stained fluid at birth?

Due to Spinal cord compression.

Due to a Tracheoesophageal fistula.

*Due to Duodenal Atresia(incomplete formation of lumen) of small bowel DISTAL to Common Bile duct(Cystic duct from gallbladder+Hepatic duct join there) trough which bile empties into duodenum.*Don't forget high risk of Tracheoesophageal fistula(Proximal esophagus has blind ending and distal part arises from trachea) in Down's syndrome patients(Check A on picture)*NEVER Forget about increased risk of AML and ALL and Early onset Alzheimmer's disease (35-40 years)<21 chromosome codes for APP which is Precursor that is cleaved into AB protein which after Phosphorylation induces APOPTOSIS of neurons.*Also beware of risk of Spinal cord compression due to atlantoaxial instability.+(Females Can be fertile while males usually are NOT)*Dudoenal atresia can manifest as polyhydramnios on fetal ultrasound during pregnancy.

Due to Hirschsprung disease in the large bowel.

24. What should be the first step when suspecting fetus can have Down's syndrome?

Perform an invasive diagnostic test immediately for definitive diagnosis.

*Triple Marker screen first even though it less SENSITIVE than Invasive diagnostic testing it is also less invasive that's why we do it firsts*Serum AFP is decreased, Urine Unconjugated Estriol(uE3) is Decreased also and only thin that is UP in DOWN's syndrome is SERUM HCG.Only after this triple marker screen you perform Invasive diagnostic testing that is not only more specific but has 100%Sensitivity(Includes Amniocentesis,CVS,percutaneous umbilical blood sampling,Cytogenetic and DNA studies for confirmation.

Ignore the suspicion and wait for the symptoms to become more apparent.

Only rely on physical exam findings to confirm the presence of Down's syndrome.

The correct approach is to start with a Triple Marker screen due to its less invasive nature and initial assessment of specific biomarkers before considering invasive diagnostic testing for confirmation.

Explanation

The correct approach is to start with a Triple Marker screen due to its less invasive nature and initial assessment of specific biomarkers before considering invasive diagnostic testing for confirmation.

25. What are the clinical manifestations of Edwards Syndrome?

Trisomy of chromosome 21, Dwarfism, Facial clefts, Polydactyly

*First of all it is Trisomy of chromosome 18*Clinically we could see:Clenched fist with overlapping fingers+Rocker bottom feet+Micrognathia(Small jaw)+Prominent occiput+Omphalocele(Liver, intestine outpouching COVERED in peritoneum), Can predispose to VSD and Malrotation of intestines+Meckel's diverticuum(Intact vitaline duct)*Horseshoe kidney is also common finding that can predispose to wilms tumor.*And of Course they have mental retardation but they die very early so..

Turner Syndrome, Short stature, Webbed neck, Shield chest, Bicuspid aortic valve

Trisomy of chromosome 13, Syndactyly, Hypertelorism, Cleft palate, Holoprosencephaly

26. Patau syndrome presents with Mental retardation+Cleft Lip/palate+POLYdactyly+VSD+Cystic Kidney what is the defect and what are some other very characteristic findings?

Down syndrome is trisomy of chromosome 21 and presents with characteristic facial features such as epicanthal folds and a flat nasal bridge.

Klinefelter syndrome is a genetic condition in males with an extra X chromosome, resulting in tall stature, gynecomastia, and infertility.

*Holoprosencephaly(Forebrain=Prosencephalon can't divide properly into 2 hemispheres) Micropthalmia(Small eyes) is another common finding.*REMEMBER patau is trisomy of chromosome 13.+Cool thing they can have 1 eye just like cyclopes...

Turner syndrome is a monosomy disorder resulting in a missing X chromosome in females, leading to short stature and infertility.

27. Is Turner's syndrome associated with mental retardation?

*Nope*Turner's syndrome is associated with normal intelligence,

It depends

Yes

Sometimes

Turner's syndrome is associated with normal intelligence.

Explanation

Turner's syndrome is associated with normal intelligence.

28. What is the most common cause of Turner's syndrome?

*Most cases of NONviable conceptuses(45 X-karyotype ) are due to PATERNAL NON-disjunction.*However those that survive mostly have Mosaic karyotype(45x/56XX) so yes MOST common cause of turner's syndrome is Mosaicism.*Note Mosaics could be with 45X/46xY and this can increase risk of Gonadoblastoma of ovary.

The presence of an extra X chromosome (47,XXX) is the main reason for Turner's syndrome.

Turner's syndrome is exclusively caused by errors during the cell division process.

Turner's syndrome is primarily caused by abnormalities in the maternal genetic material.

Turner's syndrome is characterized by the absence of one X chromosome in females, leading to various developmental and medical issues. Understanding the mechanisms behind its occurrence can shed light on potential genetic causes and risk factors.

Explanation

Turner's syndrome is characterized by the absence of one X chromosome in females, leading to various developmental and medical issues. Understanding the mechanisms behind its occurrence can shed light on potential genetic causes and risk factors.