biochem/genetics first aid

Question 1

what trinucleotide repeat codes for FMR1 gene

Answer 1

CGG (fragile X syndrome) (CGG) Chin (protruding) Giant Gonads

Question 2

Fragile X syndrome inheritance is ?

Answer 2

X linked dominant inheritance

Question 3

in Fraile X syndrome. explain what a trinucleotide repeat dose?

Answer 3

CGG repeat in FMR1 gene –> HYPERmethylation –> decrease expression.

Question 4

pt presents with post-pubertal macroorchidism (giant balls) long face w/ large jaw, large everted ears, autism predisposed to mitral vale porlapse

Answer 4

Fragile X syndrome

Question 5

most common cause of INHERITED intellectual disability and autism?

Answer 5

Fragile X syndrome. its the 2nd most common cause of GENETICALLY associated mental deficiency (after DOWNS)

Question 6

CAG repeat?

Answer 6

Huntingtons disease

Question 7

Caudate has dec Ach and GABA

Answer 7

(CAG) huntingtons

Question 8

Myotonic dystrophy trinucleotide repeat?

Answer 8

CTG

Question 9

Cataracts, Toupee (early balding in men), Gonadal atrophy

Answer 9

Myotonic dystrophy

Question 10

CGG trinucleotide repeat?

Answer 10

Fragile X syndrome

Question 11

GAA trinucleotide repeat

Answer 11

Friedreich ataxia

Question 12

Ataxic GAAit

Answer 12

friedreich ataxia

Question 13

6yo w/ persistent facial ulcer for past 2 months. extreme sensitivity to sunlight and has developed freckle on sun exposed areas since infancy. PE; skin is dry and rough and erythematous macules. there is an ulcerated plaque on face. biopsy (Squamous cell carcinoma) hes diagnosed w/ xeroderma pigmentosum. what enzyme is most likely causing this condition?

Answer 13

Endonuclease

Question 14

what disease has a deficiency in endonucleases which prevents repair of pyrimidine dimers that are formed as a result of UV light exposure? and what type of DNA repair is this described above

Answer 14

xeroderma pigmentosum.

Nucleotide excision repair.

Question 15

what phase of the cell cycle dose nucleotide excision repair occur?

Answer 15

G1 phase

Question 16

A 4-year-old male presents to his pediatrician for a routine physical examination. Physical examination reveals the presence of hyperpigmented lesions that vary in color from light brown to dark brown, axillary freckling, and Lisch nodules. The most likely gene involved is A. HFE B. NF1 a tumor suppressor gene C. Nf1 oncogene D NF2 tumor suppressor E. NF2 oncogene

Answer 16

B. NF1 gene located on chromosome 17 is a tumor-suppressor. Inactivation results in Neurofibromatosis type-1. NF2 is also TS

Question 17

HFE gene are located chromosome 6 results in ______________. autosomal recessive. leads to iron deposits in liver ,pancreas, heat, skin. iron overload due to accelerated rate of iron absorption in intestine.

Answer 17

hemochromatosis

Question 18

A 23-year-old female presents with a sore throat and a scaling rash around her mouth. Physical examination reveals hyperemia of pharyngeal mucous membranes, edema of mucous membranes, angular cheilitis, and an oily scaling nasolabial rash. The most appropriate initial pharmacological treatment is?

A. Cobalamin

B. Niacin

C.. pyridoxine

D. Riiboflavin

E. Thiamine.

Answer 18

Riboflavin

A deficiency in riboflavin can result in angular stomatitis, glossitis, and seborrheic dermatitis. A normocytic-normochromic anemia may also be appreciated on a complete blood count.

Question 19

a pt diagnosed with anorexia nervosa or malabsorptive syndrome (celiac sprue) presents with

Sorethroat, hyperemia of pharyngeal mucous membranes, edema of mucous membranes, chelitis, stomatitis, ,glossitis, and seborreheic dermatitis.

what vit is def?

Answer 19

B2 (riboflavin)

Question 20

what is the function of Rb tumor suppressor?

Answer 20

Rb, a tumor suppressor protein which holds DNA within G1 until it is ready for division.

Retinoblastoma protein is a tumor suppressor protein that prevents excessive cell growth. It holds the cell cycle during the G1 phase. The tumor, called retinoblastoma, forms when both alleles of the protein are inactivated by phosphorylation.

Question 21

A 16-year-old male presents to his primary care physician for an annual check-up. Physical examination reveals milky white skin and white hair with blue and translucent irises. Which of the following enzymes is most likely deficient in this patient?

A. acetaldehyde dehydrogenase

B. tryptophan hydroxylase.

C. Tyrosinase

D. tyrosine kinase

Answer 21

Tyrosinase.

oculocutaneous albinism.

congenital albinism is often due to a deficiency in tyrosinase, the enzyme responsible for converting tyrosine to melanin. Hereditary forms can be autosomal dominant or recessive. Albinism can also result from altered neural crest cell migration. Patients present with a varying degree of skin and hair hypopigmentation, translucent irises, and ocular complications. They are also at increased risk for skin cancer.

Question 22

A 6-month-old female with a skin rash is presented to her pediatrician. The child has also been experiencing bouts of diarrhea. The parents have also noted that the child’s skin typically reddens after exposure to sunlight. Upon physical examination, the pediatrician notes dry, scaly, well-marginated eruptions of the skin of the forehead, cheeks, and back of the hands. After laboratory testing, a deficiency in the absorption of an essential amino acid is suspected to be involved. The amino acid in question is most likely and what disease

A. glycine

B histidine

C. phenylalanine

D. Nicotiamide

E. Tryptophan

Answer 22

Tryptophan

(Hartnup disease)

defective GI absorption and renal reabsorption of the essential amino acid tryptophan, resulting in deficiency of vitamin B3.

Question 23

A 3-year-old female presents with frequent paroxysms of inappropriate laughter and hyperactivity. Physical examination reveals maxillary hypoplasia, deep-set eyes, and a large mouth with tongue protrusion. The gait is jerky and puppet-like. Osteopathic Cranial Manipulative Medicine is initiated, which the mother associates with a subjective improvement of 50% in her daughter’s ability to sleep as well the hyperactive periods. The most likely genetic cause the patient’s underlying disorder is

A. maternal uniparental disomy of chromo 15

B. Maternally-derived microdeletion on chromo 15

partial deletion of short arm of chromo 5

paternally-derived microdeletion on chromo 15

Answer 23

maternally derived microdeletion on chromo 15

angelman syndrome.

Question 24

A 28-year-old professional bodybuilder presents with alopecia, muscle pain, and an erythematous perioral macular rash. He is currently being treated for depression with sertraline. His diet consists of a massive amount of protein and raw eggs. These signs and symptoms are most consistent with a deficiency of

A. Biotin

B pyridoxine

C. Riboflavine

Answer 24

Biotin

A deficiency in biotin can occur in patients who consume a large amount of raw eggs due to the biotin binding enzyme avidin. Biotin deficiency can result in dermatitis, alopecia, enteritis, and depression.

Question 25

An underweight, 35-year-old known alcoholic female presents to the neighborhood clinic with complaints of headaches, diarrhea, memory loss, and a rash. Physical examination shows erythematous dry plaques on her arms. She states that these plaques are worse when she is in the sunlight. Because of her history, a nutrient deficiency is suspected. It is most likely that this deficiency is A. Foilic acid B. iron C. Niacin D. Riboflavin

Answer 25

**niacin** Niacin deficiency results in pellagra which clinically presents as the “4 Ds”. The 4 Ds are dermatitis, diarrhea, dementia, and death.

Question 26

where is Rrna made?

Answer 26

Nucleolus.

Question 27

Vit A functions are?

Answer 27

**antioxidant.** consistuent of **visual pigments** (**retina**l) (think retinol is vitamin A, so think **retin-A)** differentiation of epithelial cells into specialized tissues (**pancreatic cells, mucus- secreting cells**

Question 28

vit A used to treat?

Answer 28

**measles** **(APL) acute promyelocytic leukemia.** **Oral isotretinoin** to treat severe cystic acne. use ***all-trans*** **retinoic acid** to treat APL

Question 29

def in VIT A

Answer 29

**night blindness (nyctalopia)​** dry scaling skin (xerosis cutis) corneal degeneration (keratomalaxia) Bitot spots on conjunctiva; immunosuppression

Question 30

vit B1 in thiamine pyrophosphate (TPP) a cofactor for 4 dehydrogenase enzyme rxns. what are they? "think **ATP**"

Answer 30

**a**-ketoglutarate dehydrogenase (dehydrogenase TCA cycle) **T**ransketolase (HMP shunt) **P**yruvate dehydrogenase. (links glycolysis to TCA cycle) Branched-chain ketoacid dehydrogenase.

Question 31

what vitamin is involved in Beri Beri

Answer 31

**vit B1** **Dry beri beri: polyneuritis, symmetrical muscle wasting.** **wet beri beri:** high output cardiac failure (dilated cardiomyopathy) **edema**, tachycardia.

Question 32

a pt presents with polyneuritis, symmetrical muscle wasting. you make the diagnosis of **dry beri beri** what vit are they def in?

Answer 32

thiamine

Question 33

Vit B2 **riboflavin** is a component of ____________ and \_\_\_\_\_\_\_ which are used in **redox** rxns. example: succinate dehydrogenase rxn in the TCA cycle

Answer 33

**flavins** **F****AD**and**FMN** (" **F**AD and **F**MN are derived from ribo**F**lavin) (B2 = 2 atp)

Question 34

the **2C**s of B**2** deficiency are?

Answer 34

**C**heilosis (inflammation of lips, scaling, and fissures at the corners of the mouth( **C**orneal vascularization

Question 35

a pt complains of burning feet (paresthesias) on PE you see dermatitis, enteritis, alpecia, adrenal insufficiency what vit are they deficient in and what component is it essential for

Answer 35

**B5 pantothenic acid** essential component of **coenzyme A**

Question 36

a pt develops **facial flushing.** this patients symptom is most likely do to Excess of _________ vitamin and the mechanism of this flushing is due to? what can this patient take with this vitamin to prevents this rxn

Answer 36

**vit B3 niacin excess causes facial flushing** via (induced by **prostaglandin,** NOT histamine) ## Footnote **ASPIRIN**

Question 37

in glycolysis what is the rate limmint step? what is the enzyme

Answer 37

**Fructose-6-P** -------(**Phosphofructokinase-1)---------\> FRUCTOSE 1-6-bp**

Question 38

What are the 3 places where glycolysis is regulated?

Answer 38

1. **hexokinase / Glucokinase** glucose --\> G6P 2. **PFK1** . **F6P --\> F-1-6-P** 3. **Pyruvate kinase** **PEP ---\> pyruvate**

Question 39

in glycolysis for the enzymes PFK1 and Pyruvate kinase. what inhibits or activates these enzymes?

Answer 39

PFK1: activators: **AMP, fructose-2.6-bisphophate** inhibitors: **ATP, citrate** pyruvate kinase active **fructose-1,6 biphsophate** inactivates **atp and alanine**

Question 40

Vitamin B5 is essential for what cofactor?

Answer 40

CoA (a cofactor for acyl transfers) fatty acid synthase

Question 41

vit **B6 (Pyridoxine)** is a cofactor used in? (main answer, since it has multiple)

Answer 41

**Transamination** (ALT, AST)

Question 42

vit **B7 (BIOTIN)** is a cofactor for?

Answer 42

**carboxylation enzymes** (add a 2 carbon group) **pyruvate carboxylase: pyruvate (3C) --\> oxaloacetate**

Question 43

what vitamin is used in a disease that you cant reduce Fe3+ to Fe2+

Answer 43

**Vit C** (**ascorbic acid**) ancillary tx for **methemoglobinemia**

Question 44

what vitamin is required for HEME synthesis?

Answer 44

Vit **B6 pyridoxine** succinyl coa + glycine ---\> **ALA**

Question 45

your pt has been on **nitroprusside** for tx of hypertensive emergencies for a 3 days. what are they are risk of developing? how would you treat this devlopment

Answer 45

**cyanide poisoining** bc (nitroprusside contains 5 cyanide grps per molecule, toxic with prolonged infusions) TX:**NITRITES** (amyl nitrite) converts Fe2+ --\> Fe3+ in Hgb (methemoglobin) Fe3+ in HgB binds the cyanide, thus protecting the mtichondria. thus this allows them to start oxidative phosphorylation again until the cyanide is washed out of the system. this **prevents lactic acidos**is

Question 46

a pt is deficiency/defect in **fructokinase** whats the diagnosis

Answer 46

**essential fructosuria** its benign! only abnormality will be fructose in urine.

Question 48

if a patient has a deficiency in **aldolase B** what substance/substrate will be elevated?

Answer 48

**fructose 1- phosphate** **F-6-P** accumulates causing a dec in available phosphate,--\> dec ATP --\> **inhibition** of **glycogenolysis** and **gluconeogenesis** bc aldolase B enzyme catalyzes F-1-P into dihydroxyacetone-phosphate and glyceraldehyde. diagnosis **fructose intolerance.**

Question 49

a baby **just weaned** from breast milk. mom is bringing her baby in because of having a **seizure** yesterday (**hypoglycemia)** mom says she gave her baby some **fruit** for lunch with **juice** and honey 30 minutes ago before walking into the office. on physical exam the baby has an enlarged liver (**hepatomegaly**) **jaundice,** **vomiting.** what is wrong with the baby, and what is the best treatment?

Answer 49

**hereditary fructose intolerance** due to a def in **aldolase B.** treatment**. dec intake** of both **fructose** and **sucrose** (glucose + fructose) and **sorbitol..**

Question 50

why should patients with hereditary fructose intolerance avoid sorbitol?

Answer 50

bc sorbitol can be converted to fructose via sorbitol dehydrogenase. **glucose** ------**ALDOSE REDUCTASE** --\> **sorbitol** ----- sorbiotol dehydrogenase --\> **fructose**.

Question 51

what enzyme converts glucose into sorbitol

Answer 51

**aldose reductase.** accumulation of sorbitol in tissues is related to complications of hyperglycemia and diabetes.

Question 52

in metabolism of Galactose. what are the two enzymes used to eventually form glucose-1-P glactose ----(\_\_\_\_\_\_\_\_\_\_\_)---\> Glactose-1-P -----)\_\_\_\_\_\_\_\_\_\_\_\_) ---\> Glucose-1-P

Answer 52

**glactokinase.** **glactose1-phosphate** **uridyltransferase.**

Question 53

a 3 day old neonate after breast feeding. develops **jaundice**, **hepatomegaly**, and **intellectual disabiltiy.** you diagnose this child with **classic galactosemia.** **1.** what enzyme is abscence causing this? 2. if this ineonate isnt treated what will they most likely develep? 3. treatment?

Answer 53

1. **galactose-1-phosphate URIDYLTRANSFERASE.** 2. infantile **cataracts.** exclude **galactose** and **lactose** (glactose+ glucose) from diet.

Question 54

a pt with classic galactosemia. develops infantile catacts. what is the cause of the cataracts

Answer 54

build up of **galactitol** in the lens

Question 55

a young child presents with vision problems. after getting labs the child has galactose in blood (**galactosemia)** and urine (**galactosuria)** what is this this disease called?

Answer 55

galactokinase deficiency

Question 56

a child with galactokinase deficiency will most likely develop what if left untreated

Answer 56

infantile **cataracts**

Question 57

this results in excess NH3, which depletes **alpha- ketoglutarate,** leading to **inhibition** of the **TCA cycle.** pts will presents with **CNS** symptoms: tremors **(asterixis)**, slurring of speech, somnolence, vomiting, cerebral edema, blurring of vision. can be acquired (**liver disease)** or hereditary (**urea cycle enzyme def)**

Answer 57

**hyperammonemia**

Question 58

whats the treatment of **hyperammonemia**

Answer 58

**limit protein in diet** others meds givien to dec ammonia levels **lactulose** to acidify the GI tract and trap **NH4+ for excretion** **abx( rifaximin)** to dec colonic ammoniagenic bacteria. and for pts with urea cycle enzyme def: **benzoate, phenylacetat**e, or **phenylbutyrate**.

Question 59

most common urea cycle disorder ## Footnote **what enzyme is defective**

Answer 59

**ornithine transcarbamylase**

Question 60

inc carbamoyl phosphate **inc ammonia** **inc orotic acid** (derived from carbamoyl phosphate? A. ornithine transcarbamylase def B. orotic aciduria (disorder of pyrimidine syntnhesis.

Answer 60

**OTC.!** orotic aciduria does not have inc in ammonia bc not a urea cycle problem.

Question 61

inc orotic acid in bloood and urine, dec BUN symptoms of hyper ammonemia. **no megaloblastic anemai** (vs orotic aciduria)

Answer 61

ornithine transcarbamylase def

Question 62

this disease results from **cellular inability** to add **mannose-6-phospate** to **lysosomal proteins**

Answer 62

**I cell disease.**

Question 63

phenylketonuria. babies present with **musty body/urine odor,** seizures, fairr skin, eczema, growth retardation , intellectual diasability. Also can see blue eyes, pale skin. what enzyme is responsible for this? and what lab valuesdo you expect to see?

Answer 63

def in **phenylalanine hydroxylase** or (dec in cofactor (BH4) tetrahydrobiopterin = malignant PKU) labs: **inc phenylalanine** and **dec tyrosine.**

Question 64

a child was given juice with added **aspartame** (artificial sweetener) she had a seizure and her urine is musty odor whats the cause?

Answer 64

**phenylketourina.**

Question 65

child with pale skin, blond hair, blue eyes, came in complaining of getting sunburns easy. she has a history of **oculocutaneous albinism type 1.** what enzyme is she deficient in type1? and what syndrome is type 2 seen in?

Answer 65

def in **tyrosinase.** type 2 seen in **Chediakk-HIgashi syndrome.** tyrosine **transporter defect**

Question 66

cysteine residues are attached to their appropriate tRNAs by the enzyme aminoacyl-tRNA synthetase. the bound cysteine residuse are then chemically modified to form adenine. the end product of this rxn is a tRNA molecule that cocntains the cysteine anticodon but is **mischcarged** with alanine. wWOTF is most likely to occur to the alanine residue during polypeptide synthesis of alpha- hemoglobin?

Answer 66

**it will be incorporated** **into** the polypeptide chain, at the site requiring cysteine

Question 67

a healthy couple, who emigrated from eastern europe, brings in their 3 yo son to the office for eval of an **eczematous rash**. on exam the child also shows signs of **intellectual disability** and **gait abnormaltiy**and has a **musty body odor.** whats the likelyhood that this couples next child will be affected with the same disease

Answer 67

1/4 bc PKU is autosomal .**recessive**

Question 68

a baby with alkaptonuria. what is the classic presenting symptom in a child?

Answer 68

**dark** **urine** when **left standing**

Question 69

25 year old. complains of difficulty walking. on exam: * **arthritis** (large joins: knee hips) sometimes crippling. * on xray: calcification in intervertebral disc. * urine discoloration. * **bluish-black connective tissue, ear cartilage,** and sclerae (**ochronosis)** if a biopsy was done what would you expect to see? and what enzyme is deficient

Answer 69

pt has **alkaptonuria.** would see **black pigment** in cartilage and joints congenital defect in **homogentisate** **acid** **oxidase.** (in the degradative pathway of tyrosine --\> fumarate)

Question 70

how would you diagnose alkaptonuria? what would you see? whats the inheritance? **treatment!!!????**

Answer 70

**elevated homogentisate acid** autosomal recessive. dietary restriction (**tyrosine** and **phenyalaine)**

Question 71

a young boy with an **a-ketoacid dehydrogenase deficiency**is unable to degrade which acids? he has a sweet maple odor to his urine

Answer 71

**I**soleucine, **L**eucine**, V**aline (blocked degradation of **branched** amino acids due to def in branched chain a- ketoacid dehydrogenase. "**I L**ove **V**ermont **maple syrup** from maple trees (with **B1 ranches)**

Question 72

urinary cyanide-nitroprusside test is diagnositic for? (hints) autosomal recessive. cystine hexagonal stones or staghorns

Answer 72

**cystinuria**

Question 73

hereditary defect of **renal PCT** and **intestinal amino acid transporter** that prevents reabsorption of **(COLA)** **cystine, ornithine, lysine, arginine.** Diease? and treatment?

Answer 73

**cystinuria** tx: urinary alkalinization ( **potassium citrate, acetazolamine)** and chelating agents (**penicillamine)** to inc solubity of cystine stones.

Question 74

* child with pain in hands/feet (**peripheral neuropathy** * lack of sweat (**hypohydrosis**) * skin findings (**angiokeratomas)**​ ## Footnote small dark, redtopurple raised spots, dilated surface capillaries what lysosomal disease? what enzyme is def?

Answer 74

**fabrys disease** **a-galactosidase A**

Question 75

fabrys disease you will see accumulation in what? due to a def in a galactosidase A

Answer 75

**ceramide** **trihexoside.**

Question 76

a infant has papable **splenomegaly** (most common initial sign). **extensive bruising** (low platelets) painless hepatosplenomegaly, and **fatty yellow deposits in the sclera.** on microscopy the cells resemble crumpled tissue paper. you make the diagnosis of **gaucher disease.** what cell is involved in gauchers disease?

Answer 76

**macrophages!!!!** guacher cells: lipid laden macrophages filled with lipid.

Question 77

young patient presents with severe bone pain. you think its sickle cell but being a badass you know its do to avacular necrosis in gauchers disease. what is the pathophysiology of this?

Answer 77

due to bone infarction (ischemia) bc infiltrations of gaucher cells in intremedullary space.

Question 78

classic case: child of ashkenazi jew descent splenomegaly on exam anemia bruising (low platelets\_ joint pain/freactures what is the def enzyme and accumlation of?

Answer 78

**glucocerebrosidase** accumulate **glucocerebroside** gauchers disease

Question 79

what are the 3 causes of cherry red spot (spot on macula)

Answer 79

**1. neimann-pick** **2. tay-sachs** **3. central retinal artery occlusion** ( elder pt from a stroke)

Question 80

classic case: * **previously well, healthy child.** * **weakness, loss of motor skills** (progressive neurodegeration) * **enlarged liver** or **spleen** on PE!!! * **cherry red spot!** what enzyme is def, and you will see accumulation of ?

Answer 80

**niemann** **pick disease** def**spingomyelinase** accumulation **sphingomyelin** (note; not tay sachs bc tay sachs doesnt have hepatosplenomegaly)

Question 81

globoid cell leukodystrophy. what disease is this? what enzyme is deficient? what will accumulate in myelin?

Answer 81

**krabbes disease** def: **galactocerebrosidase** (major component of myelin aka breaks it down) accumulate. **galactocerebroside**

Question 82

**Tay-Sachs disease** def enzyme and accumulation of?

Answer 82

**hexosaminidase A** ## Footnote accum: **GM2 gnaglioside**

Question 83

classic presentation: **3-6 month old infant** **ashkenazi jew decent** **developmental delay** **exaggerated startle response** **cherry red spot** def of enzyme? accum of?

Answer 83

**Tay sachs** **HEXOSAMINIDASE A** accum: **GM2 ganglioside**

Question 84

* 5-9 month old with ugly ass face (gargoylism) * airway obstruction * **corneal clouding** (opacification) * **hepatosplenomegaly.** whats the diagnosis? def enzyme? and what would you see accumulate in lysosomes? inheritance pattern is **AR.**

Answer 84

**hurlers syndrome.** **A-L- Iduronidase** accumulation of **glycosaminoglycans** * **(heparan sulfate, dermatan sulfate)** **​**

Question 85

**x linked recessive.** later onset (1-2 years) compared to hulers * **NO corneal clouding** * **Behavioral probs** * learning difficulty * trouble sitting still (can **mimic ADHD**) * often **aggressive** behavior whats the most likely diagnosis? enzyme def? what will accumulate in lysosomes?

Answer 85

**hunter syndrome** def: **Iduronate sulfatase**​ accum: **heparan sulfate, dermatan sulfate.**

Question 86

subtype of **mucolipidosis** disorders named for inclusions on lighht microscopy. similiar to hurlers disease. (clouded corneas, hypotonia/motor delay, coarse facial features, Growth failure. onset first year of like) whats the pathopysiology of this?

Answer 86

Failure of processing in **GOLGI** apparatus * **\*\*\*Mannose-6-phosphate** is NOT added to lysosome proteins * normally M6P directs enzymes to lysosome, if not added --\> enzymes secreted outside of cell. KEY FINDINGS * def intracellular enzyme lvs (WBCs, fibroblasts) * inc extracellular enzyme lvs (plasma) * **multiple** enzymes abnormal * intraceulluar **inclusions** in lymphocytes and fibroblast.

Question 87

a pateint comes in with HTN crisis. history of drinking **wine** and eating **aged cheese.**shes taking a **MAO inhibitor.** the inhibited metabolism of _______________ is causing this? treatment (class and drug)

Answer 87

**tyramine** **tx: phentolamine (a1 blocker)**

Question 88

combank A 2-year-old male presents with ear pain. The child’s parents are concerned because this is his fifth ear infection this year and he “seems to always have a cold.” Initial observation of the child reveals macrocephaly, coarse facies, and a protuberant abdomen. Physical examination reveals a red, bulging ear drum, thoracolumbar kyphosis, and hepatosplenomegaly. Ophthalmic examination reveals papilledema and mild retinal degeneration. A pedigree for this condition is shown in the exhibit. This patient is most likely deficient in

Answer 88

iduronate-2-sulfatase

Question 89

how long do your glycogen stores last during fasting?

Answer 89

**24 hours**

Question 90

during fasting bw meals glucagon and epinephrine stimulate use of fuel reserves. which one has a predominant major effect (according to first aid) A. hepatic glycogenolysis hepatic gluconeogenesis, adipose release of FFA

Answer 90

bhepatic glycogenolysis.

Question 91

fatty acid SYNTHESIS occurs where? what key shuttle transporter is required

Answer 91

**cell sytoplasm** requires **CITRATE shuttle.** to shuttle citrate from mitochondrial matrix into cell cytoplasm. citrate --\> acetyl-Coa --(biotin and co2 cofactors) --\> malonyl-CoA --\> Fatty acid synthesis (palmitate, a 16 C FA)

Question 92

degratdation of FA occurs in? what transporter is required? what willl inhibit FA degradation

Answer 92

**mitochondria.** **carnitine** shuttle into mitochondria matrix FA + Coa --- (fatty acyl-coa synthetase)--\> Fatty Acyl-CoA --\> **carnitine shuttle** --\> FA- coA ---(**B-oxidation** acyl CoA dehydrogenases) --\> acetyl coa ---\> TCA cycle, or ketone bodies.. **malonyl CoA** can inhibit Fatty acyl-CoA transport

Question 93

what enzyme degrates triglycerides in small intestine prodcing FFAs

Answer 93

**pancreatic lipase**

Question 94

what enzyme causes degradation of TGs circulating in **chylomicrons** and **VLDL.** this enzyme is found in **vascular endothelial surface** and can be activated by **insulin**

Answer 94

**lipoprotein lipase (LPL)**

Question 95

what enzyme causes degradation of TGs remaining in **IDL --\> LDL**

Answer 95

**hepatic TG lipase**

Question 96

what intracellular enzyme mostly found in adipocytes casues degradation of TGs **stored in adipocytes**

Answer 96

**hormone sensitive lipase**

Question 97

**LCAT (lecithin cholesterol acyltransferase**) function ?

Answer 97

catalyzes **esterification** of 2.3 of **plasma CHOLESTEROL.** allows cholesterol to enter into core of HDL for transport

Question 98

**cholesterol estser transfer protein (CETP)** function\>

Answer 98

mediate transfer of cholesterol estero to other **lipoprotein particles.**

Question 99

Apolipoprotein **E** function?

Answer 99

mediate remnant uptake (chylomicron, chylomicron remnant, VLDL, IDL, HDL) **E**verything **E**xcept LDL

Question 100

Apolipoprotein **A**-1 function?

Answer 100

**A**ctivate **LCAT** thus found on **HDL** and chylomicron

Question 101

apolipoprotein C-II function?

Answer 101

blipoprotein lipase **C**ofactor, that **C**atalyzes **C**leavage of TGs found in **chylomicrons** and **HDL, VLDL**

Question 102

apolipoprotein **B-48** function?

Answer 102

mediate **chylomicron secretion** into lymphatics. found only in **chylomicron** and **chylomicron REMNANTS**

Question 103

what is the only apolipoprotein not on chylomicrons

Answer 103

**B-100**

Question 104

apolipoprotein **B-100** function? whats it found on

Answer 104

**binds** to **LDL** receptors allow them to unload there products into body. LDL sucks found on **VLDL, IDL, LDL**

Question 105

which organs take up LDL from circulation? what receptors are used for this?

Answer 105

**liver and peripheral tissues..** ## Footnote **B-100**

Question 106

infant with steatorrhea, and appears to have severe malabsorption labs: .**absent/low chylomicrons, VLDL, LDL, IDL,** on eye exam you see retinitis pigmentosa, ataixa, on peripheral blood smear you see **acanthocytosis** what is the disease. what is it due to? tx?

Answer 106

**abetalipoproteinemia** **autosomal Recessive** deficiency in **Apo B48, Apo B100.** Apo B48 ( chylomicrons from intestine) apo B 100 (VLDL from liver) tx: restirction of long chain fatty acids, **large .**doses of oral **vit E!!!!**

Question 107

pt with recurrent **pancreatitis, hepatosplenomegaly** and **eruptive/pruritic xanthomas** (no inc risk for atherosclerosis) blood work (**high high TG \>**1000**, Chylomicrons,** and cholesterol) the plasma looks milky autosomal **recessive.** diagnosis and whats the cause?

Answer 107

familial dyslipidemia type **1 hyperchylomicronemia** def in **lipoprotein lipase** or **apolipoprotein C-II**

Question 108

labs * type IIa heterzygotes cholesterol \>300 mg/dl **LDL, cholesterol** * type IIB homozygotes \> 700 **LDL , cholesterol, VLDL** * 20 year old present with MI!!! **accelerated atherosclerosis, tendon (achilles) xanthomas, corneal arcus** (senilis) diagnosis? def? inheritance pattern!!

Answer 108

**familial hypercholesterolemia (type II)** **autosomal DOMINANT** absent or defective **LDL receptors**

Question 109

**type III** **dysbeta-lipoproteinemia** **autosomal Recessive** inc chylomicrons, VLDL (boards and beyond says, inc cholesterol and TG) risk of **premature atherosclerosis, tuberoeruptive xanthomas,** **xanthoma striatum palmare.** what is the cuase of this

Answer 109

**defective Apo E** (apo E 2 subtype)

Question 110

**type IV hypertriglyceridemia.** ## Footnote autosomal .**dominant** labs. **inc: VLDL, TG**: HIGH (200-500) first aid says hyperTriglyceridemia (\> 1000) can cause acute pancreatitis. whats the cause

Answer 110

**hepatic** overproduction of **VLDL**

Question 111

in DNA replication in prokaryotes (e-coli) has a mutant strain that lacks a specific enzyme that is responsible for removing .**short fragments** of **RNA** that are base paired to **DNA template** what enzyme is deficient?

Answer 111

**DNA polymerase 1.** (exises RNA primer with **5 '--\> 3 ' exonuclease**

Question 112

Cystic fibrosis inheritance patterm?

Answer 112

autosomal **recessive.**

Question 113

**marfan syndrome** is due to genetic defect on what chromosome?

Answer 113

chromosome **15,** due to a defect of **Fibrillin** due to **point**mutation of the **FBN1** **gene** on chromo 15.