GENETIC DISORDERS AND CONGENITAL SYNDROMES Flashcards by Alex Kinsky

What term best describes the inheritance pattern of Marfan’s syndrome?

Autosomal dominant

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What term best describes the inheritance pattern of sickle cell disease?

Autosomal recessive

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What term best describes the inheritance pattern of thalassaemia?

Autosomal recessive

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What term best describes the inheritance pattern of Haemophilia A and B?

X-linked recessive

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What term best describes the inheritance pattern of neurofibromatosis type 1?

Autosomal dominant

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What term best describes the inheritance pattern of colour blindness?

X-linked recessive

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What term best describes the inheritance pattern of Duchenne muscular dystrophy?

X-linked recessive

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What term best describes the inheritance pattern of myotonic dystrophy?

Autosomal dominant

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What term best describes the inheritance pattern of phenylketonuria?

Autosomal recessive

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What term best describes the inheritance pattern of congenital adrenal hyperplasia?

Autosomal recessive

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What term best describes the inheritance pattern of tuberous sclerosis?

Autosomal dominant

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What term best describes the inheritance pattern of Fragile X syndrome?

X-linked recessive

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What term best describes the inheritance pattern of cystic fibrosis?

Autosomal recessive

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What term best describes the inheritance pattern of G6PD?

X-linked recessive

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What term best describes the inheritance pattern of achondroplasia?

Autosomal dominant

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What is the most common genetic cause of severe learning difficulties?

Fragile X syndrome

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What is the mutation in Fragile X syndrome?

Expansion of a triplet repeat in the FRAXA gene

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What are the clinical features of Fragile X syndrome?

Learning difficulties

Macrocephaly

Long face

Large ears

Macro-orchidism (large testes)

Taller than average

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What is the other name for trisomy 13?

Patau syndrome

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What are the features of Patau syndrome (trisomy 13)?

Microcephalic, small eyes

Cleft lip/palate

Polydactyly

Scalp lesions

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What is the other name for trisomy 18?

Edwards syndrome

What are the features of Edwards syndrome (trisomy 18)?

Micrognathia - undersized jaw

Low-set ears

Rocker bottom feet

Overlapping of fingers

What is the other name for trisomy 21?

Down syndrome

What are the dysmorphic facial features of Down syndrome?

Round face

Epicanthic folds

Flat nasal bridge

Protruding tongue

Small ears

Brushfield spots on iris

What are the non-facial dysmorphic features of Down syndrome?

Single palmar crease Flat occiput Incurved little fingers Gap between first and second toes Small stature

What are the structural defects associated with Down syndrome?

Cardiac defects (VSDs) Duodenal atresia (remember double bubble sign on x-ray)

What are the neurological features of Down syndrome?

Hypotonia Developmental delay Mean IQ of 50

What are the late medical complications of Down syndrome?

Increased risk of leukaemia Respiratory infections Hypothyroidism Alzheimer's disease Atlantoaxial instability Coeliac disease

What is the chromosomal defect that causes Turner syndrome?

45 XO - only 1 X chromosome

Is maternal age related to Turner syndrome, Down syndrome and Patau syndrome?

No. Age is not related to Turner syndrome. It is a risk factor for the other two.

What are the dysmorphic features of Turner syndrome?

Lymphoedema of the hands and feet at birth Neck webbing Widely spaced nipples Wide carrying angle (cubitus valgus) Short stature

What are the structural and functional abnormalities associated with Turner syndrome?

Gonadal dysgenesis - streak ovaries Congenital heart disease, particularly coarctation of the aorta Renal abnormalities Specific learning difficulties - visuo-spatial

What therapies can be offered to people with Turner syndrome?

Growth hormone improves final height Oestrogen therapy is given at 11 to produce maturation of secondary sexual characteristics including breast development Towards the end of puberty, progestogen is added to maintain uterine health and allow monthly withdrawal bleeds IVF will usually be needed to achieve pregnancy although natural pregnancy can occur

What is the chromosomal abnormality that causes Klinefelter syndrome?

47 XXY

What are the clinical features of Klinefelter syndrome?

Tall stature with long legs Small testes Gynaecomastia Learning difficulties

What treatment might be needed for someone with Klinefelter syndrome?

Testosterone to stimulate development of secondary sexual characteristics

What are the features of Noonan syndrome?

Referred to as the male version of Turner syndrome: Webbed neck Pectus excavatum Short stature Pulmonary stenosis

What are the features of Pierre-Robin syndrome?

Very similar to Treacher Collins syndrome: Micrognathia Posterior displacement of the tongue (may result in upper airway obstruction) Cleft palate

What are the features of Prader Willi syndrome?

Hypotonia Hypogonadism Obesity Inherited through imprinting (does not inherit gene from father)

What are the features of William's syndrome?

Short stature Learning difficulties Friendly, extrovert personality Transient neonatal hypercalcaemia Supravalvular aortic stenosis

What are the features of fetal alcohol syndrome?

Saddle-shaped nose Maxillary hypoplasia Absent philtrum between the nose and upper lip Short, thin upper lip Development delay Cardiac defects - particularly ASD

What are the features of baby born to opiate users?

Evidence of drug withdrawal: Jitterness Sneezing Yawning Poor feeding Vomiting Diarrhoea Weight loss Seizures

A 14-year-old boy is brought in by his mother who noticed her child had repeated episodes of slurred speech and gait abnormalities. On musculoskeletal examination, you notice muscle weakness, dysdiadochokinesis and spinal scoliosis. What is the mode of inheritance of this condition? X-linked recessive Autosomal dominant Point mutation X-linked dominant Autosomal recessive

Autosomal recessive - This is Friedrich's ataxia

What are the features of Friedrich's ataxia?

Bilateral spastic paresis Bilateral loss of proprioception (dysdiadochokinesis) and vibration sensation Bilateral limb ataxia Scoliosis

What are the spinal tracts affected by Friedrich's ataxia?

Lateral corticospinal tracts Dorsal columns Spinocerebellar tracts

Autosomal recessive conditions are often thought to be 'metabolic' as opposed to autosomal dominant conditions being 'structural'. What are the metabolic conditions that do not follow this rule?

Hunter's and G6PD are X-linked recessive Hyperlipidemia type II and hypokalemic periodic paralysis are autosomal dominant

Autosomal recessive conditions are often thought to be 'metabolic' as opposed to autosomal dominant conditions being 'structural'. What are the structural conditions that do not follow this rule?

Ataxia telangiectasia and Friedreich's ataxia are autosomal recessive

A 14-year-old male being investigated for iron-deficiency anaemia is found to have numerous polyps in his jejunum. On examination he is also noted to have pigmented lesions on his palms and soles. What is the likely diagnosis? Hereditary non-polyposis colorectal carcinoma Gardner's syndrome Familial adenomatous polyposis Peutz-Jeghers syndrome Hereditary haemorrhagic telangiectasia

Peutz-Jeghers syndrome

What are the clinical features of Peutz-Jeghers syndrome?

Hamartomatous polyps in GI tract (mainly small bowel) Pigmented lesions on lips, oral mucosa, face, palms and soles Intestinal obstruction e.g. intussusception Gastrointestinal bleeding

What is the inheritance pattern of Peutz-Jeghers syndrome?

Autosomal dominant

What is the prognosis of someone with Peutz-Jeghers syndrome?

Around 50% of patients will have died from a gastrointestinal tract cancer by the age of 60 years.