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Genetics Flashcards

1
Q

Describe the key features of Patau syndrome (trisomy 13).

A

Dysmorphic features, structural abnormalities affecting multiple body systems, and characteristic “rocker bottom feet.”

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2
Q

Describe the key features of Edwards syndrome (trisomy 18).

A

Dysmorphic features, severe learning disability, and “rocker bottom feet.”

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3
Q

What are the key dysmorphic features of Down’s syndrome?

A

Hypotonia (reduced muscle tone), brachycephaly (small head with flat back), short neck, short stature, flattened face and nose, prominent epicanthic folds, upward sloping palpebral fissures, and a single palmar crease.

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4
Q

What are common complications associated with Down’s syndrome?

A

Learning disability, recurrent otitis media, deafness, visual problems (myopia, strabismus, cataracts), hypothyroidism, cardiac defects (ASD, VSD, patent ductus arteriosus, tetralogy of Fallot), atlantoaxial instability, leukaemia, and dementia in adulthood.

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5
Q

What type of hearing loss is commonly seen in Down’s syndrome?

A

Conductive hearing loss due to Eustachian tube abnormalities (glue ear).

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6
Q

What is the purpose of antenatal screening for Down’s syndrome?

A

To determine which women should undergo more invasive testing to give a definitive diagnosis.

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7
Q

What is the most accurate first-line screening test for Down’s syndrome?

A

The combined test, performed between 11 and 14 weeks gestation.

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8
Q

What measurements are taken in the combined test for Down’s syndrome?

A

Ultrasound: Nuchal translucency (thickness of the back of the fetus’s neck).

Maternal blood tests: Beta-HCG (higher result indicates risk), PAPPA (lower result indicates risk).

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9
Q

What blood markers are assessed in the triple test for Down’s syndrome? How is the quadruple test different from the triple test?

A

Done between week 14-20

Beta-HCG (higher indicates risk), alpha-fetoprotein (lower indicates risk), and serum oestriol (lower indicates risk).

Quadruple test includes an additional blood test for inhibin-A (higher result indicates risk).

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10
Q

What tests are offered when the screening risk of Down’s syndrome is higher than 1 in 150?

A

Amniocentesis or chorionic villus sampling (CVS) for definitive diagnosis.

CVS is done before 15 weeks, amniocentesis is done later in pregnancy

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11
Q

What routine follow-up investigations are important for children with Down’s syndrome?

A

Regular thyroid checks (every 2 years), echocardiograms, regular audiometry (hearing tests), and regular eye checks.

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12
Q

What is the genetic cause of Klinefelter syndrome?

A

Klinefelter syndrome is caused by an additional X chromosome, making the individual’s karyotype 47 XXY.

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13
Q

What are the physical features of Klinefelter syndrome? What are some cognitive or emotional features of Klinefelter syndrome?

A

Physical: Taller height, wider hips, gynaecomastia, weaker muscles, small testicles, and reduced libido.

Cog/Emotional: Shyness, subtle learning difficulties (especially in speech and language), and infertility.

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14
Q

What is the genetic cause of Turner syndrome?

A

Turner syndrome is caused by a missing X chromosome, leading to a 45 XO karyotype.

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15
Q

What are the three classic features of Turner syndrome to remember for exams?
What are some other physical features of Turner syndrome?

A

Short stature, webbed neck, and widely spaced nipples.

High arching palate, downward sloping eyes with ptosis, broad chest, cubitus valgus, and underdeveloped ovaries.

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16
Q

What are some common associated conditions with Turner syndrome?

A

Recurrent otitis media, recurrent urinary tract infections, coarctation of the aorta, hypothyroidism, hypertension, obesity, diabetes, and osteoporosis.

17
Q

What is the genetic inheritance pattern for most cases of Noonan syndrome?

A

Noonan syndrome is primarily inherited in an autosomal dominant way.

18
Q

What are some key facial features of Noonan syndrome?
What are some additional physical features of Noonan syndrome?

A

Broad forehead, downward sloping eyes with ptosis, hypertelorism (wide-set eyes), prominent nasolabial folds, and low-set ears.

Short stature, webbed neck, and widely spaced nipples.

19
Q

What types of congenital heart disease are commonly associated with Noonan syndrome?

A

Pulmonary valve stenosis, hypertrophic cardiomyopathy, and atrial septal defect (ASD).

20
Q

How does Noonan syndrome affect male fertility?

A

Cryptorchidism (undescended testes) can lead to infertility in men.

21
Q

What are some additional conditions associated with Noonan syndrome?

A

Learning disability, bleeding disorders, lymphoedema, and increased risk of leukaemia and neuroblastoma.

22
Q

What is the inheritance pattern of Marfan syndrome?

A

Autosomal dominant.

23
Q

What protein is affected in Marfan syndrome, and what is its role?

A

Fibrillin, a key component of connective tissue.

24
Q

What are some of the physical characteristics of Marfan syndrome?

A

Tall stature, long neck, long limbs, long fingers (arachnodactyly), high arch palate, hypermobility, pectus carinatum or pectus excavatum, and downward sloping palpebral fissures.

25
Q

What are complications associated with Marfan syndrome?

A

Eye: Lens dislocation.

Cardiac: Mitral valve prolapse (with regurgitation), aortic valve prolapse (with regurgitation), and aortic aneurysms.

Other: Joint dislocations, scoliosis, pneumothorax, gastro-oesophageal reflux, and hypermobile joints.

26
Q

What gene is mutated in Fragile X syndrome, and where is it located? What protein does the gene code for, and what is its function?

A

FMR1 gene, located on the X chromosome.
The FMR1 gene codes for the fragile X mental retardation protein, which is involved in cognitive development in the brain.

27
Q

What is usually the first sign of Fragile X syndrome?

A

Delay in speech and language development.

28
Q

What are the physical features of Fragile X syndrome?

What neurological and behavioral conditions are associated with Fragile X syndrome?

A

Long, narrow face, large ears, large testicles (after puberty), and hypermobile joints (especially in the hands).

Intellectual disability, ADHD, autism, and seizures.

29
Q

What is the genetic cause of Prader-Willi Syndrome?

A

Loss of functional genes on the proximal arm of chromosome 15 inherited from the father. This can occur due to a deletion or when both copies of chromosome 15 are inherited from the mother (maternal uniparental disomy).

30
Q

What is the hallmark feature of Prader-Willi Syndrome?

What are the infantile features of Prader-Willi Syndrome?

What are some other physical features of Prader-Willi Syndrome?

What are some developmental and psychological features of Prader-Willi Syndrome?

What are the skin characteristics associated with Prader-Willi Syndrome?

A

Hallmark: Constant insatiable hunger that leads to obesity.

Infantile: Poor muscle tone (hypotonia) and feeding difficulties in infancy.

Physical: Narrow forehead, almond-shaped eyes, strabismus, thin upper lip, and downturned mouth.

Developmental/psychological: Mild to moderate learning disabilities, hypogonadism, and mental health problems (especially anxiety).

Skin: Fair, soft skin that is prone to bruising.

31
Q

What is the genetic cause of Angelman Syndrome?

A

Loss of function of the UBE3A gene, specifically the maternal copy. This can be due to a deletion on chromosome 15, a specific mutation, or two paternal copies of chromosome 15 with no maternal contribution.

32
Q

What unique behavioural traits are associated with Angelman Syndrome?

A

Happy demeanour, inappropriate laughter, fascination with water, and hand flapping.

33
Q

What are the characteristic facial and physical features of Angelman Syndrome?

A

Microcephaly, wide mouth with widely spaced teeth, and fair skin, light hair, and blue eyes.

34
Q

What are the distinctive facial features of Williams Syndrome?

A

Broad forehead, starburst eyes (a star-like pattern on the iris), flattened nasal bridge, long philtrum, wide mouth with widely spaced teeth, and a small chin.

35
Q

What personality traits are commonly associated with Williams Syndrome?

A

Very sociable and trusting personality.
“Cocktail party personality”

36
Q

What conditions might individuals with Williams Syndrome experience?

A

Cardiac: Supravalvular aortic stenosis (narrowing just above the aortic valve).

ADHD, hypertension, and hypercalcaemia.

MSRA (18 decks)

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