Genetics Flashcards
Features of downs syndrome
Characteristic facies Short neck Single palmar creases Incurved and short 5th finger Wide sandal gap Hypotonia Congenital heart defect typically AVSD Dudodenal atresia Hirschsprung disease
Downs syndrome craniofacial appearance
Round face Flat nasal bridge Upslanted palpebral fissures Brushfield spots on iris Small mouth Protruding tongue Small ear Flat occiput Third fontanelle
Downs syndrome medical complications
Delayed motor milestones Learning difficulty Short stature Increased susceptibility to infections Hearing impairment from secretory otitis media Visual impairment: cataracts, squint, myopia Risk of leukaemia and solid tumours Acquired hip dislocation Antaloaxial instabiity Hypothroidism and coeliac disease Epilepsy Early onset Alzheimers Infertility and pregnancy complications
Features Edwards syndrome
Low birthweight Prominent occiput Small mouth and chin Flexed overlapping fingers Short sternum Rocker bottom feet Cardiac and renal malformations
Features patau syndrome
Structural defect of brain Scalp defects Small eyes Eye defects Cleft lip and palate Polydactyly Cardiac and renal malformations
Features Turners Syndrome
Lymphoedema of hands and feet in neonate Short stature Spoon-shaped nails Neck webbing Wide carrying angle Widely spaced nipples Congenital heart defects esp. coarctation of the aorta Delayed puberty Ovarian dysgenesis (infertility) Hypothyroidism Renal anomalies Pigmented moles Recurrent otitis media Usually normal intellect
Ix Turners Syndrome
Antenatal US: large nuchal translucency
High LH and FSH <4y and >10y
Low LH and FSH 4-10y
Karotype 45X
Mx Turners Sydnrome
Growth hormone therapy
Oestrogen replacement
IVF
Cx Turners Syndrome
Presence of Y chromosome increased risk of gonadoblastoma
Features of Klinefelter Syndreom
Infertility Hypogonadism with small testes Normal pubertal development Gynaecomastia in adolescenc Tall stature
Examples AR disorders
Congenital adrenal hyerplasia Cystic fibrosis Friedreich Ataxia Galctosaemia Glycogen storage disorders Hurler syndrome Oculucutaneous albinism sickle cell disease Tay-Sachs disease Thalassaemia Werdnig-Hoffmann disease (SMA1)
Examples X-linker recessive disorders
Colour blindness Duchenne and Becker Muscular Dystrophy Fragile X G6PD deficiency Haemophilia A and B Hunter syndrome
Examples AD disorders
Achondroplasia Ehlers-Danlos Syndrome Familial hypercholestrolaemia Huntington disease Marfan syndrome Myotonic dystrophy Neurofibromatosis Noonan syndreom Osteogenesis imperfecta Otosclerosis Polyposis coli Tuberous sclerosis
Features Fragile X syndreom
Moderate to severe learning difficulty Macrocephaly Macroorchidism postpubertal Characteristic facies Mitral valve prolapse Joint laxity Scoliosis Autism Hyperactivity
Facial features Fragile X
Long face
Large everted ears
Prominent mandible
Broad forehead
Multifactorial and polygenetic inheritance
Congenital malformations: -neural tube defects -congenital heart disease -cleft lip and palate -pyloric stenosis -DDH -talipes equinovarus -hypospadius Childhood: -atopy -epilepsy -T1DM Adulthood: -Atherosclerosis and coronary heart disease -T2DM -Alzhiemers disease -Malignancy -Hypertension -Cerebrovascular disease
Features Noonan syndrome
Characteristic facies Mild learning difficult Short webbed neck Trident hair line Pectus excavatum Short stature Congenital heart disease: pulmonary stenosis and ASD
Characteristic face noonan’s syndrome
Deep philtrum
widely spaced eyes, usually pale blue or blue-green
low-set ears that are rotated backward.
Features williams syndrome
Short stature Tansient neonatal hypercalcaemia Congenital heart disease: supravalvular aortic stenosis Mild to moderate learning difficulty Characteristic face Friendly extraverted personality
Facial characteristics williams syndrome
small upturned nose long philtrum (upper lip length) wide mouth full lips small chin puffiness around the eyes
Features Prada willi
Characteristic facies Hypotonia Neonatal feeding difficulty Faltering growth in infancy Obesity in later childhood Hypogonadism Developmental delay Learning difficulty
Characteristic facies Prada Willi
almond-shaped eyes narrow bridge of nose narrowing of forehead at the temples thin upper lip upturned mouth
Genetic Investigations
Cytogenetic analysis: karotype
Molecular cytogenetic analysis: FISH
Microarray comparative genomic hybridization
PCR
Next generation sequencing
Linkage disequilibrium and genome wide studies
