genetics & syndromes qs

8/13/2019 Genetics & Syndromes Qs

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GENETICS & SYNDROMES 2006

Telomeres are best defined as:

A. cis-acting DNA elements responsible for segregation of chromosomes at mitosis andmeiosis.

B. proteins which bind to promotor elements to initiate transcription of a gene.

C. specialised structures which "cap" the ends of chromosomes.

D. the major non-DNA component of chromatin.

E. the sites at which crossovers occur during pachytene.

Pyloric stenosis is a disorder with polygenic inheritance. The male to female ratio isabout 4:1. Who of the following is most likely to develop pyloric stenosis?

A. The brother of an affected boy.

B. The daughter of an affected woman.

C. The daughter of an affected man.

D. The son of an affected man.

E. The son of an affected woman.

A mutation at the 5' end of an intron may interfere with splicing and be pathogenic.Which statement best summarises the consequence of such a mutation?

A. The abnormal intron blocks transcription.

B. The abnormal intron interferes with post-translational processing.

C. The abnormal intron is included in the mRNA strand.

D. The adjacent exon is duplicated.

E. The adjacent exon is not included in the mRNA strand.


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In the pedigree shown below, the individual indicated by a solid symbol is affected byan autosomal recessive disorder. No other family members are affected.

Which of the marked individuals is least likely to be a carrier of this disorder?

A. A.

B. B.

C. C.

D. D.

E. E

On average, what proportion of genetic material is shared (i.e. is identical by descent)between two first cousins? Assume the cousins are from an outbred population andthere is no consanguinity in the family.

A. 1/64.

B. 1/32.

C. 1/16.

D. 1/8.

E. 1/4.


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A 21-month-old girl presents, with her siblings, with a viral upper respiratory tractinfection. Her facial features are noted to be different from her siblings and this hasbeen present since birth. A photograph is shown (the patient is seated in the middle).She has no history of feeding or breathing difficulties as an infant. On examination hereye movements are normal with normal pupillary responses. Her smile is equal andsymmetrical. What is the most likely diagnosis?

A. Bilateral facial nerve (VII) palsy.

B. Bilateral oculomotor (III) nerve palsy.

C. Congenital myasthenia gravis.

D. Congenital ptosis.

E. Mbius syndrome.

Genomic imprinting is best defined as:

A. a process by which there is selective expression of either the paternally or maternallyinheritedallele of a gene.

B. inheritance of both copies of a chromosome from one parent.

C. massive amplification of a triplet repeat sequence within a gene.

D. skewing of X-inactivation.

E. the combined effect on a chromosomal locus of methylation of DNA and acetylation ofassociated histones.

GENETICS & SYNDROMES 2007A

QUESTION 4In an X-linked disorder which has no effect on reproductive fitness or life expectancy, the

expectedratio of affected (hemizygous) males to carrier (heterozygous) females is closest to:

A. 1:3.B. 1:2.C. 1:1.D. 2:1.E. 3:1.


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QUESTION 14A woman presents for genetic counselling early in her first pregnancy. Her husband has adisordercaused by a mitochondrial DNA point mutation; several other members of his family are alsoaffected.The risk that this baby will be affected by the same condition is closest to:

A. 0%.B. 5%.C. 25%.D. 50%.E. 100%.

QUESTION 25Patients with isolated hemihypertrophy are at increased risk of intra-abdominal tumours.Which of thefollowing tumors is the most likely to develop?

A. Adrenal carcinoma.B. Hepatoblastoma.C. Neuroblastoma.

D. Phaeochromocytoma.E. Wilms tumour


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QUESTION 56A three-year-old girl is diagnosed with adrenocortical carcinoma. Her maternal aunt died fromosteosarcoma at 12 years of age, and her maternal grandmother was treated for breastcarcinoma inher early forties. A familial tumour predisposition syndrome is suspected.The most likely mechanism for this is a germline mutation in which of the following genes?

A.APC.B. NF1.C.p53.D. RB1.E. RET.

GENETICS & SYNDROMES 2007B

QUESTION 5

A 15-year-old girl presents with a history of deterioration of night vision and peripheral vision.Her pasthistory includes mild global developmental delay, obesity and surgery in infancy for 4-limbpost-axialpolydactyly. Eye examination reveals a pigmentary retinopathy.The most likely diagnosis is:

A. autosomal recessive retinitis pigmentosa.B. bardet-biedl syndrome.C. choroideraemia.D. McKusick-kaufman syndrome.E. refsum disease.


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QUESTION 26

Which of the following observations regarding a rare disorder would provide the bestevidence ofautosomal dominant inheritance?

A. Father and son affected.B. Father and daughter affected.C. Mother and son affected.D. Mother and daughter affected.E. Male and female cousins affected.

QUESTION 24A two-year-old boy is found to have severe bilateral sensorineural deafness. There is nofamily historyof note. On examination, he has partial heterochromia iridis, white eyelashes, a broad nasal

bridgewith telecanthus, and several depigmented patches on his trunk and limbs.What is the most likely diagnosis?

A. Branchio-oto-renal syndrome.B. Oculo-cutaneous albinism.C. Pendred syndrome.D. Tuberous sclerosis.E. Waardenburg syndrome.


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GENETICS & SYNDROMES 2008


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GENETICS & SYNDROMES REM + PP 2009

Question 17

A child presents with tetralogy of Fallot and a submucous cleft palate. What isthe most likely cause for this phenotype?


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A) AneuploidyB) Contiguous gene deletionC) In-utero sequenceD) Maternal toxin ingestion

Question 29

A pregnant woman consults you regarding the chances of her child being

affected by cystic fibrosis. She has two siblings who have cystic fibrosis.

A pedigree is shown

[The pregnant womans parents were unaffected, her partner is unaffected]

Considering the carrier frequency for cystic fibrosis in the general population is

1 in 25, what are the chances of her unborn child having cystic fibrosis?

A) 1/50B) 1/75C) 1/100D) 1/150E) 1/300

Question 31

Which of the following is embryologically defective in the 22q11 deletion?

A) 1stand 2ndpharyngeal arches

B) 1stand 2ndbranchial archesC) 2ndand 3rdpharyngeal archesD) 2ndand 3rdbranchial archesE) 3rdand 4thpharyngeal arches

Question 47

A boy is diagnosed with schizophrenia. He has a dizygotic twin brother and

another male sibling. What is the risk of schizophrenia of the twin and the other

sibling?

A5%

B10%

C20% in twin and 10% in sibling

D50% in twin and 10% in sibling

E50% in twin and 5% in sibling

Question 55

What is the most common CFTR gene mutation in Caucasians?

A) A three nucleotide deletion in the F508 geneB) A three nucleotide insertion in the F508 gene


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C) Deletion of phenylalanine at position 508 of the protein

D) Substitution of aspartate for phenylalanine at position 508 of the protein

E) Substitution of aspartate for phenylalanine at position 508 of the gene

Question 37

A 15 year-old boy presents with rectal bleeding. Colonoscopy shows >200polyps. The diagnosis is subsequently confirmed as familial adenomatous

polyposis coli.

What is the chance of developing colorectal neoplasia in FAP in the pts lifetime?

A) 20 %B) 40 %C) 60 %D) 80 %E) 100 %

Question 43

A 3 year-old boy presents with elbow pain after being pushed into a doorframe

at day-care. He has a past history of a tracheo-oesophageal fistula which was

repaired in infancy. He also has butterfly vertebrae of T11 noted incidentally

noted on X-ray and GORD requiring treatment.

On examination, he complains of elbow pain, and has limitation of pronation.

X-ray forearm given

[Shows union of radius and ulna proximally, no obvious fractures and normal

bone density]

What is the most likely diagnosis?

A) Ulnar fracture


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B) Humeral (condyle) fractureC) Radial head dislocationD) Radial-ulnar synostosisE) Rickets

Question 52An infant is diagnosed with Downs Syndrome which is confirmed on FISH study.

In terms of genetic counseling, what is the most important reason that a full

karyotype is required on this infant?

A) To detect other chromosomal defects in the childB) Robertsonian translocation involving Chromosome 21C) AneuploidyD) To detect mosaicismE) FISH has poor specificity

Question 74

A previously well child presents with recurrent abdominal pain. There are no

other bowel symptoms. Upper and lower GI studies demonstrate polyps. His face

has the appearance below.

[Photo given of mouth with freckle-like markings on lips and peri-oral region]


A) Familial adenomatous polyposisB) Juvenille polyposisC) LEOPARD syndromeD) NF 1E) Peutz-Jegher syndromeF)

GENETICS & SYNDROMES REMEMBERED 2010

A couple meet at a Short Peoples Convention. The male partner has acondroplasia, and

he is the only member of his family to have the disease. The female partner is of normal

stature but her brother has acondroplasia. What is the chance that they will have a

child with achondroplasia?

a)


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e) 100%

When fluorescent in situ hybridization (FISH) is used for antenatal diagnosis, which

genetic abnormality is most likely to be detected?

a. Aneuploidy

b. Deletionsc. Duplicationsd. Mosaicism

e. Translocations

A female infant who has features of Turner syndrome is noted to have an ejectionsystolic murmur.


A) ASDB) Bicuspid aortic valveC) Coarcation of the aortaD) Peripheral pulmonary stenosisE) VSD

A newborn baby is found to be severely hyperbilirubinaemic within 24hours after birth. There is a family history of similar neonatal jaundice. Afamily tree of the phenotype is shown:

What is the most likely condition to have caused this presentation?

A) Alpha 1 antitrypsyn deficiencyB) GalactosaemiaC) Crigler-NajjirD) D.Gilbert syndromeE) Glucose 6 phosphate deficiency


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What is the most common mode of genetic mechanism forretinoblastoma in children?

A) somatic mutation and loss of heterozygosityB) germline mutation and loss of heterozygosity

C) mutation of both somatic geneD) ???E) ???

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