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  • Question 1 - A 13-year-old boy presents to the hospital with a history of multiple episodes...

    Correct

    • A 13-year-old boy presents to the hospital with a history of multiple episodes of generalized tonic-clonic seizures for the past week. Prior to this, he has had multiple admissions for the same reason and has been on anti-epileptic drugs since the age of 11 months with poor control. He was born of non-consanguineous parents with an uneventful birth history. There is no history of seizures in other family members. On examination, he has multiple hyperpigmented papules over the nasolabial region suggestive of adenoma sebaceum. A full body examination revealed a total of 5 hypopigmented ash leaf macules over the lower limbs along with a shagreen patch over the lateral aspect of the left buttock. The mode of inheritance of the boy's condition has a pattern similar to that of:

      Your Answer: Neurofibromatosis Type 1

      Explanation:

      Based on the clinical scenario provided, the most probable diagnosis for this patient would be tuberous sclerosis which is an autosomal dominant condition.Among the options provided, only Neurofibromatosis Type 1 is inherited by an autosomal dominant pattern. Other options:- Beckwith-Wiedemann syndrome is an example of an imprinting disorder and results from abnormalities of inheritance or methylation of chromosome 11p15.- Cystic fibrosis is an autosomal recessive condition.- Duchenne Muscular Dystrophy is an example of an X-linked recessive condition.- Hypophosphataemic (Vitamin D resistant) rickets is an X-linked dominant condition.

    • This question is part of the following fields:

      • Genetics And Dysmorphology
      158.5
      Seconds
  • Question 2 - Which among the following genetic conditions, does NOT present with cataracts? ...

    Incorrect

    • Which among the following genetic conditions, does NOT present with cataracts?

      Your Answer: Lowe syndrome

      Correct Answer: Neurofibromatosis type 1 (NF1)

      Explanation:

      Neurofibromatosis Type 1 (also known as von Recklinghausen disease) does not present with cataracts.The eye findings in NF1 are Lisch’s nodules, which are pigmentary lesions seen on the iris and constitute one of the major diagnostic features in this condition. Note:Interestingly, in another syndrome closely related to it, Neurofibromatosis type 2 (NF-2), cataracts can occur. Early detection in family members may be made by finding lens opacities (both congenital polar cataracts and posterior lenticular opacities). Other options:- Incontinentia pigmenti is an X-linked dominant disorder with pigmentary skin changes, mental retardation and eye involvement in 40% of cases. – Myotonic dystrophy is a triplet-repeat disorder with neurological symptoms and cataracts. – Lowe syndrome (oculo-cerebro-renal syndrome) is an X-linked recessive condition. Males with this X-linked recessive condition have cataracts, hypotonia, mental retardation, generalised aminoaciduria and renal tubular acidosis with hypophosphatemia. – Wilson disease is an inborn error of copper metabolism. The clinical features include hepatic involvement, progressive neurological features, eye involvement, including Kayser–Fleischer rings and cataracts.

    • This question is part of the following fields:

      • Genetics And Dysmorphology
      17.6
      Seconds
  • Question 3 - In X linked dominant inheritance, what is the chance of an affected father's...

    Correct

    • In X linked dominant inheritance, what is the chance of an affected father's daughter inheriting the condition?

      Your Answer: 1

      Explanation:

      In the pattern of mendelian inheritance, X- linked dominant inheritance means that all who inherit the X chromosome will present with the condition. In the case of maternal x-linked inheritance sons and daughters have an equal chance of inheriting the condition as there is a 50% chance of inheriting the defective X chromosome from their mother as opposed to a non affected X chromosome from their father. However in paternal X-linked dominant inheritance, sons will be unaffected as they inherit a Y chromosome from their father while daughters are sure to inherit the defective X-chromosome.

    • This question is part of the following fields:

      • Genetics And Dysmorphology
      27.8
      Seconds
  • Question 4 - Which of the given clinical findings is the hallmark of Trisomy 21? ...

    Correct

    • Which of the given clinical findings is the hallmark of Trisomy 21?

      Your Answer: Hypotonia

      Explanation:

      Trisomy 21 (Down’s syndrome)is a genetic disorder characterized by the presence of an extra copy of chromosome 21 in all the body cells, mostly due to non-disjunction during gametogenesis. Robertsonian translocation occurs only in about 2-4% of the cases. A variety of clinical features are found in trisomy 21 due to multi-system involvement but the hallmark is hypotonia, which is present in almost all the cases of trisomy 21. Different types of leukemias are also found in association with down’s syndrome, but they are not the hallmark. Atlantoaxial subluxation is secondary to hypotonia, which induces joint and ligament laxity. Other clinical findings are hypothyroidism, Alzheimer’s disease, Hirschsprung’s disease, and pulmonary hypertension.

    • This question is part of the following fields:

      • Genetics And Dysmorphology
      184.4
      Seconds
  • Question 5 - Two healthy parents have two children, one with cystic fibrosis and the other...

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    • Two healthy parents have two children, one with cystic fibrosis and the other one healthy. What are the chances of the third child being a carrier?

      Your Answer: 1 in 2

      Explanation:

      Cystic fibrosis has an autosomal recessive pattern of inheritance, meaning that a person might be a carrier of the disease without developing it. If the unaffected partner is a carrier, then there is a 50% chance of inheritance and a 50% chance of having a child who is a carrier. However, if the partner is not a carrier, the offspring will not develop the disease but the possibility of being a carrier raises up to 100%.

    • This question is part of the following fields:

      • Genetics And Dysmorphology
      2.8
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  • Question 6 - A 4-year-old girl with an abnormal facial appearance has an ejection systolic murmur...

    Correct

    • A 4-year-old girl with an abnormal facial appearance has an ejection systolic murmur radiating to between her scapulae. A radio-femoral delay was also found. Which of the following is the most probable cause?

      Your Answer: Turner's syndrome

      Explanation:

      These cardiovascular findings are suggestive of coarctation of the aorta, which is common among patients with Turner’s syndrome. Physical features of Turner’s syndrome include a short neck with a webbed appearance, a low hairline at the back of the head, low-set ears, and narrow fingernails and toenails that are turned upward.Atrioventricular septal defect is the most common cardiac anomaly in Down’s syndrome. Structural heart defects at birth (i.e., ventricular septal defect, atrial septal defect, patent ductus arteriosus) are common in Edward’s syndrome. Pulmonary stenosis with or without dysplastic pulmonary valve and hypertrophic cardiomyopathy are common in Noonan’s syndrome. Supravalvar aortic stenosis and peripheral pulmonary stenosis are found in William’s syndrome.

    • This question is part of the following fields:

      • Genetics And Dysmorphology
      16.2
      Seconds
  • Question 7 - Which of the following are not a recognized feature of Down's syndrome? ...

    Correct

    • Which of the following are not a recognized feature of Down's syndrome?

      Your Answer: Ataxic gait

      Explanation:

      Ataxic gait is not a direct association of Down’s syndrome. All other given responses are associated with Down’s syndrome.

    • This question is part of the following fields:

      • Genetics And Dysmorphology
      15.9
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  • Question 8 - An infant under investigation for persistent jaundice has a systolic murmur consistent with...

    Correct

    • An infant under investigation for persistent jaundice has a systolic murmur consistent with pulmonary valve disease. Ophthalmological assessment reveals a posterior embryotoxon.Which of the following skeletal abnormalities is to be considered in this child?

      Your Answer: Butterfly vertebrae

      Explanation:

      The combination of cholestasis, congenital heart disease (mainly affecting the pulmonary vasculature) and anterior-segment abnormalities (primarily posterior embryotoxon) suggests a diagnosis of Alagille syndrome. Clinical features:The facial features are characteristic and include a prominent forehead, deep-set eyes and a pointed chin. The most common skeletal manifestation is butterfly vertebrae, a clefting abnormality of the vertebrae most often seen in the thoracic spine and described in up to 87% of cases. Radio-ulnar synostosis and short phalanges have also been described in Alagille but less frequently. Note: Pectus excavatum is a feature of Noonan syndrome, one of the differential diagnoses of pulmonary valve disease.

    • This question is part of the following fields:

      • Genetics And Dysmorphology
      25.7
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  • Question 9 - Growth failure can be managed with recombinant human growth hormone (Somatropin) in the...

    Correct

    • Growth failure can be managed with recombinant human growth hormone (Somatropin) in the all of the following conditions except:

      Your Answer: Achondroplasia

      Explanation:

      Somatropin is a recombinant human growth hormone used to treat growth failure conditions associated with natural growth hormone deficiencies. According to the UK National Institute for Health and Care Excellence, these conditions include, Prader-Willi syndrome, Noonan syndrome, short stature Homeobox (SHOX) gene deficiency, Turner’s syndrome, chronic renal insufficiency and children who are small for gestational age. Treatment of short stature in achondroplasia has not seen any significant changes with somatotropin.

    • This question is part of the following fields:

      • Genetics And Dysmorphology
      8.9
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  • Question 10 - Which of the following is true regarding Prader-Willi syndrome? ...

    Correct

    • Which of the following is true regarding Prader-Willi syndrome?

      Your Answer: Affected individuals typically have small gonads

      Explanation:

      Prader-Willi Syndrome is a genetic disorder that occurs when a chromosome from paternal chromosome 15q is deleted or unexpressed during the formation of the egg or sperm, or in embryonic development. Individuals usually inherit one copy of this gene from each parent, and in this case on the paternal gene remains active in parts of the brain and other organs. This phenomenon is known as genetic imprinting, and is also seen in Angelman’s syndrome. Symptoms seen in Prader-Willi range from poor muscle tone during infancy to developmental and cognitive delays. Many individuals suffer from hypogonadism that affects fertility in both males and females. In Angelman’s syndrome the maternal chromosome 15q is unexpressed. The condition is also called happy puppet syndrome as affected children present with a happy demeanour, ataxic gait, and flapping movements of the limbs.

    • This question is part of the following fields:

      • Genetics And Dysmorphology
      11.6
      Seconds
  • Question 11 - Angelman’s syndrome is characterized by a gene deletion in which of the following...

    Correct

    • Angelman’s syndrome is characterized by a gene deletion in which of the following chromosomes?

      Your Answer: Chromosome 15

      Explanation:

      Angelman Syndrome is a genetic disorder that affects the nervous system. The features of this condition include intellectual disability, a delay in developmental milestones, and movement disorders. The features occur as a result of the deletion or mutation of the maternal copy of the UBE3A gene located on Chromosome 15q. Though individuals usually inherit one copy of this gene from each parent, only the maternal gene remains active in parts of the brain. This phenomenon is known as genetic imprinting, and is also seen in Prader-Willi syndrome.

    • This question is part of the following fields:

      • Genetics And Dysmorphology
      5.4
      Seconds
  • Question 12 - Advanced paternal age is a risk factor for which of the following diseases?...

    Correct

    • Advanced paternal age is a risk factor for which of the following diseases?

      Your Answer: Retinoblastoma

      Explanation:

      Advancing paternal age has been linked with lower quality sperm leading to a reduction in overall fertility and an increase in the occurrence of various medical disorders in the fetus. Advanced paternal age has been implicated as a risk factor for diseases like retinoblastoma, achondroplasia, autism spectrum disorders, schizophrenia, and acute lymphoblastic leukaemia. Down’s syndrome is mostly considered a consequence of advanced maternal age, but advanced paternal age has also been implicated as a risk factor.

    • This question is part of the following fields:

      • Genetics And Dysmorphology
      7.6
      Seconds
  • Question 13 - A boy with Tay-Sachs disease has a sister who is normal and healthy....

    Correct

    • A boy with Tay-Sachs disease has a sister who is normal and healthy. What is her risk of being a carrier for the condition?

      Your Answer: 0.66

      Explanation:

      Tay-Sachs disease is an autosomal recessive disease. For the brother to present with the disease, both parents must be carriers. Therefore, with each pregnancy the probability that the child would be affected is 1 in 4| the probability that the child would be a carrier is 2 in 4| and the probability that the child would be unaffected is also 1 in 4. Unaffected children have a 2 in 3 chance, or 66%, of becoming a carrier according to the patterns of autosomal recessive inheritance.

    • This question is part of the following fields:

      • Genetics And Dysmorphology
      5.8
      Seconds
  • Question 14 - A family of five members presents to the genetics clinic for further evaluation....

    Correct

    • A family of five members presents to the genetics clinic for further evaluation. The father, one boy and one girl present with a short stature, large heads, short digits, and trident hands. Genetic evaluation reveals they are all heterozygotes for a specific mutation. The rest of the family, the mother and the other daughter, do not carry this mutation. What is the pattern of inheritance?

      Your Answer: Autosomal dominant with complete penetrance

      Explanation:

      In this case, the affected individuals are all heterozygotes. Therefore, the mutation is autosomal dominant. Also, the mother does not carry the mutation, further confirming the autosomal dominant nature of the disease, which is most probably achondroplasia.

    • This question is part of the following fields:

      • Genetics And Dysmorphology
      17
      Seconds
  • Question 15 - Which of the following exhibits low genetic penetrance? ...

    Correct

    • Which of the following exhibits low genetic penetrance?

      Your Answer: Gaucher disease

      Explanation:

      Penetrance is defined as the percentage of individuals having a particular mutation or genotype who exhibit clinical signs or phenotype of the associated disorder or genotype.Gaucher disease is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.

    • This question is part of the following fields:

      • Genetics And Dysmorphology
      8.6
      Seconds
  • Question 16 - Which one of the following fulfils the diagnostic criteria for neurofibromatosis type 1?...

    Correct

    • Which one of the following fulfils the diagnostic criteria for neurofibromatosis type 1?

      Your Answer: There is groin freckling and a plexiform neurofibroma

      Explanation:

      Neurofibromatosis is a genetic disease caused by the mutation of the neurofibromin gene on Chromosome 17. The diagnostic criteria for Neurofibromatosis type 1 are two or more of the following:-6 or more cafe au lait macules-2 or more cutaneous neurofibroma or one plexiform Neurofibroma-Axillary of groin freckling -Optic pathway glioma -2 or more Lisch nodules (hamartomas of the iris seen on slit lamp examination)-Bony dysplasia (such as sphenoid wing dysplasia, bowing of the long bones, or pseudarthrosis)-First degree relative with neurofibromatosis type 1

    • This question is part of the following fields:

      • Genetics And Dysmorphology
      8.8
      Seconds
  • Question 17 - A new-born baby is noted to have low-set ears, rocker-bottom feet and overlapping...

    Correct

    • A new-born baby is noted to have low-set ears, rocker-bottom feet and overlapping of her fingers.What is the most likely diagnosis?

      Your Answer: Edward's syndrome

      Explanation:

      The trisomy 18 syndrome, also known as Edwards syndrome, is a common chromosomal disorder due to the presence of an extra chromosome 18, either full, mosaic trisomy, or partial trisomy 18q. The condition is the second most common autosomal trisomy syndrome after trisomy 21.Currently, most cases of trisomy 18 are prenatally diagnosed, based on screening by maternal age, maternal serum marker screening, or detection of sonographic abnormalities (e.g., increased nuchal translucency thickness, growth retardation, choroid plexus cyst, overlapping of fingers, and congenital heart defects ).The main clinical features represent the clues for the diagnosis in the perinatal period and include prenatal growth deficiency, characteristic craniofacial features (dolichocephaly, short palpebral fissures, micrognathia external anomalies of the ears, and redundant skin at the back of the neck), distinctive hand posture (overriding fingers: index finger overlapping the third and 5th finger overlapping the 4th), nail hypoplasia, short hallux, underdeveloped thumbs, short sternum, and club feet and major malformations (particularly involving the heart).

    • This question is part of the following fields:

      • Genetics And Dysmorphology
      10.9
      Seconds
  • Question 18 - Which of the following is NOT a gonadal or sexual differentiation disorder? ...

    Correct

    • Which of the following is NOT a gonadal or sexual differentiation disorder?

      Your Answer: XXX (Triple X Syndrome)

      Explanation:

      The correct answer is triple X syndrome with a genotype of XXX and an almost normal female phenotype. The extra X chromosome is inactive. The final phenotype of an individual is determined after normal sexual and gonadal differentiation, a process that involves several genes located on chromosomes X and Y. Disorders of sexual differentiation result in cases of ambiguous genitalia and are caused by a number of genetic abnormalities. Among these disorders is the turner syndrome with a genotype of 45X0, characterized by gonadal dysgenesis and ovarian failure. DAX-1 gene mutation leads to congenital adrenal hypoplasia and hypogonadotropic hypogonadism, which results in virilization of female external genitalia. Campomelic dysplasia results from mutation of the SOX-9 gene, leading to 46XY sex reversal. Danys-Drash syndrome is characterized by disordered sexual development in affected males due to the mutated WT-1 gene, which also causes Wilm’s tumour.

    • This question is part of the following fields:

      • Genetics And Dysmorphology
      8.6
      Seconds
  • Question 19 - A mother brings her 4-year-old boy who is known to have Down's syndrome...

    Correct

    • A mother brings her 4-year-old boy who is known to have Down's syndrome to the outpatient clinic as she is concerned about his vision. Which one of the following eye problems is least associated with Down's syndrome?

      Your Answer: Retinal detachment

      Explanation:

      Individuals with Down syndrome are at increased risk for a variety of eye and vision disorders. Fortunately, many of these eye problems can be treated, especially if discovered at an early age. The quality of life can be further enhanced by the proper assessment and correction of eye problems. The most common eye findings include:- Refractive errors – Children with Down syndrome are more likely to need glasses than are other children. This may be due to myopia (near-sightedness), hyperopia (far-sightedness), and/or astigmatism. Refractive error may develop early in life or later on.- Strabismus – Between 20% and 60% of individuals with Down syndrome have eyes that are misaligned (strabismus). Esotropia (eyes that drift in) is most common while exotropia(eyes that drift out) occurs less frequently. Strabismus may be treated with glasses, patching and/or eye muscle surgery.- Keratoconus – A cone shaped distortion of the cornea (front layer of the eye), occurs in up to 30% of those with Down syndrome. Keratoconus is usually diagnosed around puberty and should be monitored regularly. Blurred vision, corneal thinning, or corneal haze may result from keratoconus. Keratoconus is worsened by eye rubbing| therefore, eye rubbing should be discouraged.- Cataracts – There is an increased incidence of congenital cataracts (present at birth) as well as acquired cataracts (develop later). Cataracts may progress slowly and should be monitored regularly, with surgical treatment performed when appropriate.- Glaucoma- There is an increased risk of infantile glaucoma (elevated pressure within the eye).- Blepharitis – Inflammation of the eyelids with redness at the edge of the lids and crusting around the lashes may occur and cause a feeling of dryness or burning. Treatment is with eyelid hygiene and topical antibiotics.- Tearing – Excessive tears or watering of the eyes may occur because the drainage channels are blocked or narrow (nasolacrimal duct obstruction). This may require surgical intervention.- Nystagmus – This is an involuntary “back-and-forth” movement or shaking of the eyes. It can affect vision to a mild or severe degree.

    • This question is part of the following fields:

      • Genetics And Dysmorphology
      13.8
      Seconds
  • Question 20 - Which is true regarding XYY syndrome? ...

    Correct

    • Which is true regarding XYY syndrome?

      Your Answer: Affected individuals are usually asymptomatic

      Explanation:

      47,XYY syndrome is characterized by an extra copy of the Y chromosome in each of a male’s cells. Although many males with this condition are taller than average, the chromosomal change sometimes causes no unusual physical features. Most males with 47,XYY syndrome have normal production of the male sex hormone testosterone and normal sexual development, and they are usually able to father children.47,XYY syndrome is associated with an increased risk of learning disabilities and delayed development of speech and language skills. Affected boys can have delayed development of motor skills or hypotonia.Other signs and symptoms of this condition include hand tremors or other involuntary movements (motor tics), seizures, and asthma. Males with 47,XYY syndrome have an increased risk of behavioural, social, and emotional difficulties compared with their unaffected peers. These problems include attention-deficit/hyperactivity disorder (ADHD)| depression| anxiety| and autism spectrum disorder.Physical features related to 47,XYY syndrome can include increased belly fat, macrocephaly, macrodontia, flat feet (pes planus), fifth fingers that curve inward (clinodactyly), widely spaced eyes (ocular hypertelorism), and scoliosis. These characteristics vary widely among affected boys and men.

    • This question is part of the following fields:

      • Genetics And Dysmorphology
      83.6
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