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76 Cards in this Set

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Biochem/Genetics

What causes high and low alpha fetoprotein?
High: in open neural tube defects

Low: down syndrome
Biochem/Genetics

What three maternal screening tests are different in a mom carrying a Down's baby?
alpha fetoprotein: low
urine for unconj estriol: low
beta-hCG: high
nucheal translucency (fluid around babies neck) increased
Biochem/Genetics

What is one example of Robertsonian translocation? what is robersonian translocation?
Robertsonian translocation in which one part of a chromosome is transfered a homologous chromosome.

In 4% of Down's the mother usually has a fused chr 21 (leaving her 45xx). This forms one long 21 that really is two functional 21's (since they are both functional: parent is normal)

Child ends up with three functional 21's. p.120Gs
Biochem/Genetics

What are the findings in a pt with Downs?
Mental retardation (MCC of congenital m. retard)
flat facial profile
prominent epicanthal folds
simian crease
duodenal atresia
congenital heart disease (mc septum primum - type ASD due to endocardial cushion defects)
Alzheimers dz in affected individuals > 35yo
Increased risk of ALL
Biochem/Genetics

What is the MC deletion syndrome?
Cri-du-chat

Deletion of short arm of chromosome 5

Causes mental retardation
crylike cat
VSD
microcephaly
epicantal folds (skin fold of the upper eyelid)
Biochem/Genetics

Describe genomic imprinting of Prader-Willi?
Normally one of two parental alleles is imprinted (inactivated) by methylation rendering it inactive.

In Prader-Willi the normally methylated allele is mom's.

The problem happens when the normal (unmethylated) paternal allele is deleted.

=mental retardation, obesity, hypogonadism, hypotonia
Biochem/Genetics

Describe genomic imprinting of Angelman's sydrome:
Normally dad's allele on chr 15 is methylated (imprinted) into inactivation.

Angelman's occurs when mom's allele on chr 15 is deleted

= mental retardation
seizures, ataxia, inappropriate laughter (happy puppet)
Biochem/Genetics

Three genetic diseases assoc with advanced paternal age (2)
1. Marfans
2. achondroplasia
Biochem/Genetics

What is the MCC of Down's syndrome (genetic error)
meiotic nondisjunction of homologous chromosomes which is associated with advanced maternal age.

This nondisjunction can occur in anaphase I or anaphase II
Biochem/Genetics

What is Edwards syndrome?

Life span
A autosomal tripsomy on chromosome 18

Findinngs:
severe mental retardation
rocker bottom feet
low-set ears
micrognathia (small jaw)
congenital heart disease
clenched hands
prominent occiput

death usually occurs within 1 yr of birth
Biochem/Genetics

What is Patau's syndrome?
A autosomal trisomy on chr 13 (Puberty)

Findings:
severe mental retardation
micrphthalmia
microcephaly
cleft lip/palate
abnormal forebrain structures
polydactyly
congenital heart disease

death usually occurs within one year.
Biochem/Genetics

What is Turners syndrome?
a female (x,o)

Presents with:
short stature
ovarian dysgenesis (streak ovary)
webbing of neck
coarctation of aorta

no barr body
MCC of amenorrhea
Biochem/Genetics

Klinefelter's syndrome
male xxy (1:850)

Testicular atrophy
eunuchoid body shape
tall
long extremities
gynecomastia
female hair distribution
dysgenesis of seminiferous tubules --> decrease inhibin --> increase FSH
Abnormal leydig cell function --> decreased testosterone --> increased LH --> increased estrogen

caused by presence of an inactivated barr body (x-chromosome)
Biochem/Genetics

What type of baby has the nuckle, nuckle, dimple, nuckle?
Turners
Biochem/Genetics

What do Turner women have an increased risk for?
dysgerminomas (ovaries are removed)
Biochem/Genetics

What specifically went wrong in Klinefelters syndrome?
Nondisjuction in the first step of meiosis resulting in an XXY genotype.
Biochem/Genetics

How do Klinefelters pts appear before puberty?

Patho
Normal

Patho: in Klinefelters sertoli cells do not synthesize inhibin (used to negatively feedback on FSH)

No Sertoli cells:
No inhibin --> increase FSH
No ABP --> alot of testosterone made from the Leydig cells floating around --> all of this testosterone will be aromatized into estrogens.
Biochem/Genetics

Lab work on a Klinefelters pt?
Low testerone --> high LH
Low inhibin --> high FSH
azoospermina = no sperm
high serum estradiol
Biochem/Genetics

What are the only two AD disorders that are enzyme deficiences?
(most are structural defects in proteins and receptors)
Acute intermittent porphyria: deficiency of uroporphyrinogen synthase

Hereditary angioedema: C1 esterase inhibitor deficiency
Biochem/Genetics

Three features that can be seen in AD disorders?
1. late manifestion
2. exhibit penetrance: affected person never expresses the disease but disease but does transmit the disease to their children.
3. exhibit varible expressivity: affected people have different levels of severity of the disease
Biochem/Genetics

Two AD disorders with 100% penetrance:
Familial polyposis
Adult polycystic kidney disease
Biochem/Genetics

Describe fetal alcohol syndrome:
Newborns of mothers who consumed significant amounts of alcohol (teratogen) during pregnancy (highest risk at 3-8wks) have increased incidence of congenital abnormalities, including pre- and postnatal developmental retardation, microcephaly, facial abnormalities, limb dislocation, and heart and lung fistulas.

Mechanism may include inhibition of cell migration.

The number one cause of congenital malformations in the US.
Biochem/Genetics

What are 22q1 syndromes

How can is variably present?
22q1 syndromes: CATCH-22

Cleft palate
Abnormal facies
Thymic aplasia --> T cell deficiency
Cardiac defects
Hypocalcemia secondary to parathyroid aplasia

Cause: microdeletion at chr 22q11

Can variably present as DiGeorges (thymic, parathyroid, and cardiac defects) or velocardiofacial syndrome (palate, facial, and cardiac defects)
Biochem/Genetics

What gene and chromosome is affected in CF?

Inheritance?
FA
Autosomal recessive disorder in CFTR gene on chr 7

It is MC caused specifically by a deletion of Phe 508
Biochem/Genetics

What is defective in CF?
There is a defective Cl channel that causes secretion of abnormally thick mucus that plugs lungs, pancreas, and liver
Biochem/Genetics

What is CF associated with?
Assoc with recurrent pulmonary infections caused by pseudomonas and S.aureus as well as chronic bronchitis, bronchiectasis, pancreatic insufficiency (malabsorption and steatorrhea), meconium ileus in newborns.

Infertility in males due to absent vas deferens.

Fat soluble vitamin deficiencys (DEAK)
Biochem/Genetics

What is the diagnostic test for CF?
Increased conc of Cl of ions in sweat test is diagnostic
Biochem/Genetics

What is the most common lethel genetic disease in Caucasians?
CF
Biochem/Genetics

What is the treatment of CF?
N-acetylcyteine to loosen mucus plugs
Biochem/Genetics

Mneumonic for all the x-linked recessive disorders?
Be Wise Fool's GOLD Heeds False Hope

Bruton's agammaglobulinemia, Wiskott-Aldrich syndrome, Fragile X
G-6PD deficiency
Ocular albinism
Lesch-Nyhan syndrome
Duchenne's muscular dystrophy
Hemophilia A and B
Fabry's disease
Hunter's syndrome
Biochem/Genetics

Compare the two muscular dystrophies:
Duchenne's (x-linked)
and
Beckers
Duchenne's:
frameshift mutation --> deletion of dystrophin gene --> accelerated muscle breakdown
Onset before 5 years of age
Weakness begins in pelvic girdle muscles and progresses superiorly.
Psudeohypertrophy of calf muscles due to fibrofatty replacement of muscle
Cardiac myopathy
Pts require assistance to stand (use the Gowers maneuver: use upper extremeities to stand = proximal lower limb weakness)

Beckers: mutated dystrophin gene is less severe than Duchennes
Biochem/Genetics

Mneumonic Duchenne's:
Duchennes: Deleted Dystrophin
Biochem/Genetics

How do you diagnose duchenne's?
Diagnose any muscular dystrophy:
by increased CPK and muscle biopsy
Biochem/Genetics

Fragile X syndrome?
Triplet repeat disorder (CGG)x-linked defect affecting the methylation and expression of FMRI gene.

fragile X = eXtra-large testes, jaw, and ears
The 2nd most common cause of genetic mental retardation (MC: downs)

Associated with micro-orchism (enlarged testes), long face with a large jaw, large everted ears, hyperextensible, and autism
Biochem/Genetics

What is different in the presentation of Fragile X in the different genders?
It is a triplet repeat disorder that may show genetic anticipatio (germlike expansion in females)

MOW because its on the x-chromosome so females have two sets of repeats.
Biochem/Genetics

What are the four trinucleotide repeat disorders?

Genetic feature?
Try (trinucleotide) Hunting for my fried eggs (X)

Huntingtons
Myotonic dystrophy
Friedreichs ataxia

May show anticipation (disease severity increases and age of onset decreases in successive generations)
Biochem/Genetics

What are the essential amino acids?
Ketogenic: Leu, Lys
Glucogenic/ketogenic: Ile, Phe, Trp
Glucogenic: Met, Thr, Val, Arg, His

PriVaTe TIM HALL and arg and his are required during periods of growth
Biochem/Genetics

What are the acidic amino acids?
Asp and Glu
Biochem/Genetics

What are the basic amino acids?
Arg, Lys, His (arg is the most basic and his has no charge at body pH)
Biochem/Genetics

What one use for two of the basic amino acids, arg and lys?
They are in high number in histones which bind negatively charged DNA
Biochem/Genetics
Amino acid derivatives:

Phenylalanine:
Phenylalanine --> tyrosine --> dopa and thyroxine

Dopa --> melanin and dopamine

Dopamine --> NE --> Epi
Biochem/Genetics
Amino acid derivatives:

Tryptophan
Tryptophan makes:
Niacin --> NAD
Serotonin
Melatonin
Biochem/Genetics
Amino acid derivatives:

Histidine
Histidine makes Histamine
Biochem/Genetics
Amino acid derivatives:

Glycine
Glycine --> Porphyrin --> Heme
Biochem/Genetics
Amino acid derivatives:

Arginine
Arginine makes:
Creatine
Urea
NO
Biochem/Genetics
Amino acid derivatives:

Glutamate
Glutamate makes GABA (glutamate decarboxylase-B6)
Biochem/Genetics

Familial dyslipidemias:

Type I (hyperchylomicronemia)
Increased: chylomicrons

Elevated blood levels: TG, cholesterol

Pathophys: lipoprotein lipase def or altered C-II
Biochem/Genetics

Familial dyslipidemias:
Type IIa: hypercholesterolemia
Increased: LDL

Elevated blood levels: Cholesterol

Pathophys: decreased LDL receptors
Biochem/Genetics

Familial dyslipidemias:
Type IIb
Type IIa: combined hyperlipidemia

Increased: LDL, VLDL

Elevated blood levels: TG, cholesterol

Pathophys: Hepatic overproduction of VLDL
Biochem/Genetics
Familial dyslipidemias:

Type III
Type III: dysbetalipoproteinemia

Increased: IDL, VLDL

Elevated blood levels: TG, cholesterol

Pathophys: Altered apoE
Biochem/Genetics
Familial dyslipidemias:

Type IV
Hypertriglyceridemia (type IV)

Increased: VLDL

Elevated blood levels: TG

Pathophys: hepatic overproduction of VLDL (like Type II)
Biochem/Genetics

Familial dyslipidemias:

Type V:
Mixed hypertriglyceridemia

Increased: VLDL, chylomicrons

Elevated blood levels: TG, cholesterol

Pathophys: increased production and decreased clearance of VLDL and chylomicrons
Biochem/Genetics

What are microtubules?
Cylindrical structures that is 24nm in diameter and of variable length.
It is composed of a helical array of polymerized dimers of alpha and beta tubulin (13 per circumference)

Each dimer has 2GTP bound.
Incorporates into flaggella, cilia, mitotic spindles.

Grows slowly and collapses quickly.

Microtubles are also involved in slow axoplasmic transport in neurons.
Biochem/Genetics

What drugs act on microtubules?
1. mebendazole/thiobendazole (antihelminthic)
2. taxol (anti-breast CA)
3. vincristine/vinblastine
4. colchicine (anti-gout)
Biochem/Genetics

What is Chediak-Higashi syndrome?
A syndrome caused by microtuble polymerization defect resulting in decreased phagocytosis.
Biochem/Genetics

Describe the structure of cilia:
Cilia: 9+2 arrangement of microtubles

Dynein is an ATPase that links peripheral 9 doublets and causes bending of cilium by differential sliding of doublets

Molecular motors
Dynein = retrograde
Kinesin = anterograde
Biochem/Genetics

What is a plasma membrane composed of?
Asymmetric fluid bilayer

Contains cholesterol (50%), phospholipids (50%), spingolipids, glycolipids, and proteins

High cholesterol or long saturated fatty acid content --> increased melting temperature
Biochem/Genetics

What is phosphatidylcholine?
Major component of RBC membranes, of myelin, bile, and surfactant
(aka DPPC: dipalmitoyl phosphatidylcholine)

Used in the esterification of cholesterol (LCAT: lecithin-cholesterol acyltransferase)
Biochem/Genetics

What junction is seen at the apical surfaces of glands?
Tight junction (seal off intercellular spaces)
Biochem/Genetics

What junction is seen around osteocytes in the lamellae?
Gap junctions: in CNS, cardiac m, smooth m, bone (not in epithelia)
Biochem/Genetics

What is used to form a desmosome and where are they found?
Desmosome: joins epithelial cells using keratin filaments
Biochem/Genetics

What forms the channels of gap junctions?
Connexons
Biochem/Genetics

Collagen: what are the types?
Collagen: most abundant protein in the human body
Organizes and strengthens extracellular matrix

Type I (90%): Bone, Skin, Tendon, dentin, fascia, cornea, late wound repair (Type one: bONE)

Type II: Cartilage (including hyaline), vitreous body, nucleus pulposus)
Type TWO: carTWOlage

Type III (Reticulin): skin, blood vessels, uterus, fetal tissue, granulation tissue

Type IV: Basement membrane or basal lamina (Type FOUR: under the FLOOR)
Biochem/Genetics

What does Ouabain do?
Inhibits the Na/K ATPase pump by binding to the K site.
Biochem/Genetics

Adult Polycystic kidney disease
Adult polycystic kidney disease
AD

Always bilateral
massive enlargement of kidneys due to multiple large cysts
Patients present with pain, hematuria, hypertension, progressive renal failure
90% is due to APKD (chr 16)
Associated with polycystic liver disease, berry aneuryisms, mitral valve prolapse
Juvenile form is recessive
Biochem/Genetics

Familial Hypercholesterolemia (hyperlipidemia type IIA)
Elevated LDL owing to defective or absent LDL receptor.
Heterozygotes (1:500) have cholesterol = 300
Homozygotes (rare) have cholesterol = 700+

Pts have severe atherosclerotic disease early in life, and tendon xanthomas (classically in the Achilles tendon)
MI may develop before age 20
Biochem/Genetics

Marfan's syndrome
Fibrillin gene mutation --> connective tissue disorders
Skeletal abnormalities: tall with long extremities (arachnodactyly)
Pectus excavatum
hyperextensive joints
long, tapering fingers and toes
Wing span is greater than the height, ectopia lentis

Cardiovascular complications: cystic medial necrosis of aorta --> aortic incompetence and dissecting aortic aneuyrsms
Floppy mitral valve
Biochem/Genetics

Neurofibromatosis type I (von Recklinghausen's disease)
Findings: cafe-au-lait, neural tumors, Lisch nodules (pigmented iris hamartomas)
Also marked by skeletal disorders (scoliosis), optic pathway gliomas, pheochromocytoma, and increases tumor susceptibility.
On long arm of chromosome 17

(there are 17 letters in von Recklinghausen)
Biochem/Genetics

Neurofibromatosis type II
Bilateral acoustic neuroma, juvenile cataracts.
NF2 gene on chromosome 22

type 2 = chr 22
Biochem/Genetics

Tuberous sclerosis
Findings: facial lesions (adenoma sebaceum), hypopigmented "ash leaf spots" on skin, cortical and retinal hamartomas, seizures, mental retardation, renal cysts, cardiac rhabdomyomas.

Incomplete penetrance, variable presentation
Biochem/Genetics

Von Hippel-Lindau disease
Findings:
hemangioblastomas of retina/cerebellum/medulla;
about 1/2 of affected individuals develop multiple bilateral renal cell carcinomas and other tumors.

Associated with deletion of VHL gene (tumor suppressor) on chr 3 (3p).

Von-hippel Lindau = 3 words for chromosome 3
Biochem/Genetics

Huntington's disease
Findings: depression, progressive dementia, choreiform movements, caudate atrophy, and decreased levels of GABA and ACh in the brain.
Symptoms manifest in affect individuals between the ages of 20 and 50.
Gene located on chr 4
Triplet repeat disorder

"Hunting 4 food"
Biochem/Genetics

Familial adenomatous polyposis
Colon becomes covered with adenomatous polyps after puberty.
Progresses to colon CA unless resected.
Deletion on chr 5

5 letters in polyp
Biochem/Genetics

Hereditary spherocytosis
Spheroid erythrocytes; hemolytic anemia; increased MCHC

Splenectomy is curative
Biochem/Genetics

Achondroplasia
AD cell-signalling defect of fibroblast growth factor (FGF) receptor 3.
Results in dwarfism; short limbs, but head and trunk are normal size.

Associated with advanced paternal age.
Biochem/Genetics

List the autosomal recessive diseases
AR
1. cystic fibrosis
2. albinism
3. alpha1-antitrypsin def
4. phenylketonuria
5. thalassemias
6. sickle cell anemia
7. glycogen storage diseases
8. mucopolysaccaridoses (except Hunters)
9. sphingolipidoses (except Fabry's)
10. infant polycystic kidney disease
11. hemochromatosis