Genetic Diseases Flashcards
Trisomy 21
Gain of function disorder 1/700 Caused by: - nondisjuntion of 21st csome - robertsonian translocation - long arm of csome 21 joins csome 14 or 15 -Mosaic down syndrome Clinical Manifestions Prenatal - brachycephaly - hypoplastic nose - sandal gap - mild hydonephrosis - clinodactyly - nuchal thickening Postnatal -simian crease -abundant neck skin - flattened nose and face - upward slanting eyes
Trisomy 18
gain of function mutation (1/6000 affected) Caused by: nondisjunction in csome 18 or sperm or egg (meiosis II) mosaic trisomy 18 - only affects some cells partial trisomy 18 - results from partial, unbalanced translocations Clinical Manifestations: Prenatal: - hydrocephaly - holoprocencephaly - microcephaly - ventral septal defect - omphalocele Postnatal: - rocker bottom feet - clenched fists w/ overlapping fingers - microcephaly - small jaw
Trisomy 13
Gain of function disorder (1/4000) Causes: - meiotic I nondisjunction of csome 13 - robertsonian translocation - mosaic Clinical Manifestations: Prenatal: - holoprocencephaly - VSD - polydactyly - omphalocele Postnatal: - midline defects - microcephaly - polydactyly - cleft lip/palate - proboscis - mental retardation
22q Microdeletion (velo cardio facial syndrome) (DiGeorge Syndrome)
Disorder caused by deletion of a piece near the middle of csome 22 1/4000 newborns, typically not inherited but can be passed down (autosomal dominant) Clinical Manifestations: - heart defects - cleft palate - immune system problems - low Ca levels
Klinefelter XXY
1/500-1/1000 males Caused by nondisjunction during meiosis or mitotic cell division - 47XXY Clinical Manifestations: - poor beard growth - small testes - female type pubic hair - osteoporosis - breast tissue enlargement
Turners XO
1/2000 females Caused by nondisjunction resulting in monosomy 45X Clinical Manifestations: - short stature - no menstruation - brown spots - widely spaced nipples - poor breast development - rudimentary ovaries
Familial Hypercholesterolemia
1/500 LDL - R gene deletion; loss of function mutation Autosomal Dominant disorder Heterozygous 1/500 Homozygous 1/1000000 Clinical Manifestations: Angina Buildup of cholesterol in tissues Calves cramping Stroke-like symptoms sores on toes that don’t heal eventual heart attack
Gaucher’s Disease
1/900 in Ashkenazi Jews; 1/15 are carriers Autosomal recessive Most common form of lysosomal storage disease Clinical Manifestations: hepatosplenomegaly anemia thrombocytopenia fatigue lung disease
PKU
1/10000-1/15000 phenylalanine metabolism defect Autosomal recessive disorder Clinical manifestations: seizures intellectual disability
Duchenne Muscular Dystropy
1/3500 males X-linked recessive disorder Mutation in protein dystrophin - which is protein that connects the sarcolemma to the cytoskeleton Beckers muscular dystrophy produces shortened partially functional dystrophin therefore muscle degeneration is not as bad as DMD Clinical Manifestations: Pseudohypertrophy - enlarged calf muscles cardiomyopathy
Neurofibromatosis
Loss of function mutation, mutation in the NR tumor suppressor
Autosomal dominant - 100% penetrant
Clinical Manifestations:
6+ cafe au lait spots
Freckles in groin or axillary area
2+ neurofibromas
2+ lisch nodules
optic glioma
distinctive bone lesions
growth may be stunted
possible hypertension
Marfan Syndrome
Autosomal dominant pleiotropic disorder
thousands of different mutations in this gene have been known to cause this disease
variable expressivity
Recurrence risk: 1/2
Connective tissue disorder that causes problems in the ocular, skeletal and cardiovascular systems
Clinical manifestations:
long and slender limbs
scoliosis
pectus carinatum and pectus excavatum
arachnodactylyl
joint hypermobility
myopia
mitrovalve prolapse
dilation of aorta
