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39 Cards in this Set
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Hemophilia A
Inheritance pattern? Frequency? Clinical features? Gene affected? Treatment? Life expectancy? |
Inheritance pattern: X linked recessive
Frequency: Males-1/10,0000 Clinical features: Coagulation disorder with prolonged bleeding & easy bruising Gene affected: Coagulation Factor VIII Treatment: Administering Factor VIII concentrate Life expectancy: Approaches that of healthy population (excluding HIV or hepatitis) |
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Huntington disease (Huntington's Chorea)
Inheritance pattern? Gene affected? Clinical features? Life expectancy? |
Inheritance pattern: Autosomal dominant
Gene affected: Coding region of HD, The CAG repeat gets too large and becomes unstable Normal_Less than 36 Intermediate_36-39 (usually affected) Affected_Greater than 40 Clinical features: Mean age of presentation 35-44years with an average survival of 15-18years after diagnosis. Progressive motor, cognitive, & psychiatric abnormalities that become incapacitating as HD progresses, Chorea (nonrepetitive jerks that can't be voluntarily controlled) Life expectancy: Mean age of death is 55 |
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Angelman syndrome:
Inheritance pattern? Clinical features? Gene affected? |
Inheritance pattern: Maternally inherited (paternal copy of the gene is imprinted [methylated] so it is not expressed).
Clinical features: Short stature, Always smiling, Severe mental retardation, Spasticity, Dystonia Gene affected: Ubiquitin UBE3A gene on 15q11 |
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Achondroplasia:
Inheritance pattern? Clinical features? Gene affected? Life expectancy? |
Inheritance pattern: Autosomal dominant, 100% penetrance, De novo mutations cause 75-80% of cases
Clinical features: Short stature, Proximal shortening of the limbs, Limits of elbow extension, Bow legs, Lumbar lordosis, Large head with frontal bossing, Normal intelligence Gene affeted: Fibroblast growth factor receptor-3 (FGFR3). Life expectancy: Usually normal |
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Cystic fibrosis
Inheritance pattern? Gene affected? Disease frequency? |
Inheritance pattern: Autosomal recessive
Gene affected: CFTR (chlorine channel gene) (e.g. mutation - has a 3 base pair (in-frame) deletion). Chromosome 7. Disease frequency: 1/2,000 |
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Prader-Willi syndrome:
Inheritance pattern? Clinical features? Gene affected? |
Inheritance pattern: Paternally inherited (maternal copy of the gene is imprinted [methylated] so it is not expressed).
Clinical features: Hyperphagia, Obesity, Hypogonadism, Small hands & feet, Mental retardation, Associated with cryptorchidism Gene affected: SNRPN gene on 15q13 |
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Turner syndrome:
Chromosomal abnormality? Clinical features? Frequency: |
Chromosomal abnormality: Monosomy X, Less frequent in liveborn infants by far the most common chromosome anomaly in spontaneous abortions
Clinical features: Short female, Low posterior hair line, Webbed neck, Broad chest & widely spaced nipples, Pigmented nevi, Peripheral lymphedema at birth, Cubitus valgus [elbows are turned in], Coarctation of aorta Frequency: 1/5,000 females |
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Hereditary non-polyposis colon cancer (HNPCC):
Inheritance pattern? Gene affected? Clinical features? Onset? |
Inheritance pattern: Autosomal dominant
Gene affected: MSH2 & MLH1 and some other MMR gene mutations responsible for about 60% most cases Clinical features: Has extremely variable expression. Individual has predisposition to colon [usually in distal colon] & extra-colonic cancers (endometrium, ovary, stomach, urogenital). Onset: Between 20-80 years. |
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Familial erythermalgia [Paroxysmal extreme pain disorder]:
Gene affected? |
Gene affected: Gain of function mutation to SCN9A gene that encodes for a Na+ channel protein in certain neurons called Nav1.7
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Congenital insensitivity to pain:
Gene affected? |
Gene affected: Loss of function mutation to SCN9A gene that encodes for a Na+ channel protein in certain neurons called Nav1.7
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PKU (phenylketonuria):
Inheritance pattern? Disease frequency? Screening? Treatment? |
Inheritance pattern: Autosomal recessive
Disease frequency: 1/1,000 Screening: Phenylalanine blood level test 3 days after birth. Treatment: Phenylalanine-restricted diet early in infancy to prevent mental retardation |
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OCA (oculocutaneous albinism):
Inheritance pattern? Gene affected? Biochemistry? Disease frequency? |
Inheritance pattern: Autosomal recessive
Gene affected: Tyrosinase coding gene Biochemistry: Lack of melanin Disease frequency: 1/20,000 |
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Tay Sachs:
Inheritance pattern? Gene affected? Biochemistry? Clinical features? Disease frequency? |
Inheritance pattern: Autosomal recessive
Gene affected: Hexoseaminidase gene has four base pair (frameshift) insertion, Chromosome 15 Biochemistry: Accumulation of gangliosides Clinical features: Child appear to develop normally for the first few months of life. Then, as nerve cells become distended with fatty material, a relentless deterioration of mental and physical abilities occurs. The child becomes blind, deaf, and unable to swallow. Muscles begin to atrophy and paralysis sets in. Other neurological symptoms include dementia, seizures, and an increased startle reflex to noise. Usually die by age 4, from recurring infection Disease frequency: Normal-1/360,000 Ashkenazi Jews-1/3,600 |
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Hemochromatosis:
Gene affected? Carrier frequency? Clinical Features? Treatment? Life expectancy? |
Gene affected: Variety of mutations, but most common is an individual homozygous for a Cys282Tyr mutation in the HFE gene [Chr 6]
Carrier frequency: USA-1/10 Clinical Features: Increased absorption & deposition of iron which can lead to liver, pancreatic, & cardiac damage. Skin may also become pigmented. Treatment: Phlebotomy, which is effective in preventing organ damage if instituted early Life expectancy: Normal |
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Duchenne muscular dystrophy (DMD):
Inheritance pattern? Clinical features? Gene affected? Life expectancy? |
Inheritance pattern: X linked recessive, 1/3 of cases represent new mutations, 5-10% of carrier females have muscle weakness, while only a few have severe disease
Clinical features: Progressive muscle weakness & loss of muscle mass. Gene affected: Dystrophin (< 5% normal levels) Life expectancy: Symptoms by 5yrs, in wheelchair by 11yrs, death in teens or early 20s. |
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Becker Muscular Dystrophy:
Inheritance pattern? Clinical features? Gene affected? |
Inheritance pattern: X linked recessive, new mutations account for a small percentage of cases
Clinical features: Progressive muscle weakness & loss of muscle mass. Not as severe as DMD. Gene affected: Dystrophin (30-80% normal levels) |
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Hypophosphatemic rickets (vitamin D-resistant rickets):
Inheritance pattern? Biochemistry? |
Inheritance pattern: X-linked dominant
Biochemistry: The ability of the kidney tubules to reabsorb filtered phosphate is impaired |
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Sickle cell anemia:
Inheritance pattern? Clinical features? Gene affected? Life expectancy? |
Inheritance pattern: Autosomal recessive, Heterozygous individuals have increased malaria resistance
Clinical features: Symptoms by 4 months of age, Blocked blood vessels cause acute painful crisis lasting hours to days. Repeated crises cause damage to kidneys, lungs, bones, eyes, & CNS Gene affected: B-globin chain (Glu6Val) Life expectancy: Shortened |
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Down syndrome:
Chromosomal abnormality? Clinical features? Frequency? |
Chromosomal abnormality: Trisomy 21, Usually due to non-disjunction during meiosis I in mother, Most common human malformation
Clinical features: Short stature, Brachycephaly (wide head) with flat occiput, Short neck, Loose skin on the nape, Flat nasal bridge, Ears low-set with characteristic folds, Mouth is open, protruding tongue, Epicanthic folds [skin fold of the upper eyelid (from the nose to the inner side of the eyebrow) covering the inner corner (medial canthus) of the eye] & Upslanting palpebral fissures, Hands are short & broad, Cardiac malformations, Mental retardation Frequency: Most common human malformation syndrome |
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Patau syndrome:
Chromosomal abnormality? Clinical features? Frequency? |
Chromosomal abnormality: Trisomy 13
Clinical features: Multiple anomalies (cardiac in 90% of cases) with very poor prognosis (few weeks) Frequency: 1/5000 births |
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Edwards syndrome:
Chromosomal abnormality? Clinical features? Frequency? |
Chromosomal abnormality: Trisomy 18
Clinical features: Multiple anomalies (cardiac in 90% of cases) with very poor prognosis (few weeks) Frequency: 1/5000 births |
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Klinefelter syndrome:
Chromosomal abnormality? Clinical features? Frequency: |
Chromosomal abnormality: 47,XXY
Clinical features: Tall male, Infertile, Hypogonadism, Learning difficulties in some patients, May have poor psychosocial adjustment Frequency: 1/1000 males |
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XYY syndrome:
Clinical features? Frequency? |
Clinical features: Tall male, Normal sexual development, Normal intelligence, Frequent behavioral problems
Frequency: 1/1000 males |
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Trisomy X:
Clinical features? Frequency? |
Clinical features: Female, Usually tall, Usually normal sexual development, Learning difficulties in some patients, Occasional behavioral problems
Frequency: 1/1000 females |
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Xeroderma pigmentosum:
Inheritance pattern? Biochemistry? Clinical symptoms? Frequency? |
Inheritance pattern: Autosomal recessive
Biochemistry: Defects in the nucleotide excision repair Clinical symptoms: Clinical sun sensitivity (Cells hypersensitive to UV), > 1000-fold increase in skin cancer, 20% patients have progressive neurological degeneration Frequency: USA & Europe: 1/250,000 Japan: 1/40,000 |
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Familial hypercholesterolemia
Inheritance pattern? Gene affected? |
Inheritance pattern: Autosomal dominant or recessive
Gene affected: LDL receptor gene has a mis-sense mutation |
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Fragile X syndrome:
Inheritance pattern? Gene affected? Clinical features? |
Inheritance pattern: X-linked
Gene affected: 5' untranslated region of FMR1, The CGG repeat gets too large and becomes unstable Normal_Less than 60 Intermediate_60-200 (usually unaffected) Affected_Greater than 200 Clinical Features: Mental retardation, Hyperactivity, Short attention span, Tactilely defensive (having a negative response to touch), Hand-flapping, Hand-biting, Poor eye contact, Perseverative speech (ontinued repetition of words or phrases), Hyperextensible MP joints (double jointed), Large or prominent ears, Large testicles, Simian crease or Sydney line (horizontal crease that goes from edge to edge across the palm) Family history of mental retardation |
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Mytonic dystrophy:
Inheritance pattern? Gene affected? Clinical features? |
Inheritance pattern: Autosomal dominant
Gene affected: 3' untranslated region of DMPK on chromosome 19, The CTG repeat gets too large and becomes unstable Normal_Less than 30 Intermediate_50-80 (may be mildly affected) Affected_80-2000 Clinical features: Muscles contract but have decreasing power to relax. With this condition, the muscles also become weak and waste away. Myotonic dystrophy can cause mental deficiency, hair loss and cataracts. |
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Retinoblastoma:
Inheritance pattern? Gene affected? |
Inheritance pattern: Autosomal dominant, however gene affected is recessive (the other copy is almost always damaged in at least one cell during mitotic division)
Gene affected: Rb gene (chromosome 13), which controls the progression of G1 to S phase |
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Familial Adenomatous Polyposis (FAP):
Inheritance pattern? Gene affected? Clinical features? Diagnosis? |
Inheritance pattern: Autosomal dominant with very high penetrance
Gene affected: APC (chromosome 5) tumor suppressor gene. There are many different mutations. Clinical features: Multiple (>100) benign adenomatous polyps, usually in the proximal colon with a high chance that one or more of the polyps will progress to a carcinoma Diagnosis: Colonoscopy to see polyps |
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Attenuated Familial Adenomatous Polyposis (AFAP):
Inheritance pattern? Gene affected? Clinical features? |
Inheritance pattern: Autosomal dominant with lower penetrance than FAP
Gene affected: APC (chromosome 5) tumor suppressor gene. There are many different mutations. Clinical features: Variable number of polyps that are often found in the proximal colon, with a later age of onset |
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Inherited breast cancer:
Inheritance pattern? Contributing genes? |
Inheritance pattern: Autosomal dominant with penetrance up to 85% for breast and 55% for ovarian cancer in females. Males also have an increased risk of breast, prostate, pancreatic, & other cancers.
Contributing genes: BRCA1 & BRCA2 are the 2 genes identified so far. Both are involved in repair of DNA double-strand breaks. |
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Coronary artery disease:
Contributing genes? Risk increase? |
Contributing genes: CDKN2A and CDKN2B genes on chromosome 9p21.3 play an important role in regulation of cell cycle and may be implicated through their role in growth inhibition, in the pathogenesis of atherosclerosis.
Risk increase: 36% for each copy in a person's genome |
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Diabetes Mellitus Type I (T1DM):
Genetics or Environment? Contributing genes? Biochemistry? Onset? Treatment? |
Genetics or Environment: Environment plays a large role because environmental changes trigger the disease
Contributing genes: Has one major risk locus (IDDM1) & up to 20 minor loci that interact to confer susceptibility to environmental triggers Biochemistry: Complete loss of B-cell function due to autoimmune reaction Onset: Peak age in adolescence Treatment: Regular injections of insulin to control blood sugar |
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Diabetes Mellitus Type 2 (T2DM):
Genetics or Environment? Contributing genes? Biochemistry? Onset? Treatment? |
Genetics or Environment: Genetics is the primary determining factor
Contributing genes: Has no major predisposing locus but the contribution of loci varies between populations. The most important gene is Transcription factor-7-like 2 (TCF7L2) that is a transcription factor when mutated can reduce insulin secretion Biochemistry: Insulin resistance Onset: Usually affects older persons Treatment: Dietary restriction, Oral hypoglycemic medication, Some require insulin |
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Maturity-onset diabetes of the young (MODY):
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A rare form or diabetes which shows a high penetrance within families.
Usually due to mutations in single genes (monogenic form of diabetes) that lead to B-cell dysfunction |
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Obesity:
Contributing genes? Chromosome #? |
Contributing genes: FTO gene is a gene that has been associated with obesity
Chromosome #: 16 |
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Ultra-rapid, Extensive, Intermediate, & Poor drug metabolizer:
Gene involved? Frequency? |
Gene involved: Cytochrome P450 2D6 (CYP2D6) is one of the most important enzymes in the metabolism of xenobiotics & acts on 25% of all prescription drugs including
(1) Selective serotonin reuptake inhibitors (SSRI) (2) Tricycic antidepressants (TCA) (3) Beta blockers (4) Type 1A antiarrhythmics (5) Activates codeine to morphine in the body Frequency (considerable variability in its expression in the liver): Slow acting: 10% Super fast acting: 7% |
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Warfarin (Dose variation):
Genes involved? |
Genes involved:
CYP2C9: Explains 10% of dose variations & is responsible for the break down of the drugs into metabolites VKORC1: Explains 25% of dose variations and is a gene for subunit C1 in the protein Vitamin K epoxide reductase, which is the target for the drug. Warfarin: (1) An oral anticoagulant used to prevent thrombosis and embolism in many situations (2) Has a narrow therapeutic index (3) Complex pharmacology (4) Errors in dosing can lead to severe & possible life-threatening bleeding or clotting (5) Its affect has to be monitored by frequent blood testing (6) It inhibits the action of Vitamin K epoxide reductase, which helps limit blood coagulation |
