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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)
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
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
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
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
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
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
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.
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
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
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
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
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
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
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.
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)
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
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
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
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
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
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
XYY syndrome:
Clinical features?
Frequency?
Clinical features: Tall male, Normal sexual development, Normal intelligence, Frequent behavioral problems

Frequency: 1/1000 males
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
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
Familial hypercholesterolemia
Inheritance pattern?
Gene affected?
Inheritance pattern: Autosomal dominant or recessive

Gene affected: LDL receptor gene has a mis-sense mutation
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
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.
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
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
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
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.
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
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
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
Maturity-onset diabetes of the young (MODY):
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
Obesity:
Contributing genes?
Chromosome #?
Contributing genes: FTO gene is a gene that has been associated with obesity

Chromosome #: 16
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%
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