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What disorder is often associated with duodenal atresia?
Down's Syndrome.
List the trisomies and their associated syndromes.
1. Down's Syndrome: trisomy 21

2. Edward's Syndrome: trisomy 18

3. Patau's Syndrome: trisomy 13
Remember:

Down's = Drinking age (21)

Edward's = Election age (18)

Patau's = Puberty (13)
Screening for Down's in Pregnancy
1. Decreased α-fetoprotein
2. Increased β-hCG
3. Decreased estriol,
4. normal inhibin A
Screening for Edward's syndrome in pregnancy
1. Decreased α-fetoprotein
2. Decreased β-hCG
3. Decreased estriol
4. Normal inhibin A
Screening for Patau's syndrome in pregnancy
1. Normal α-fetoprotein
2. Normal β-hCG
3. Normal estriol
4. Normal inhibin
Contrast presentations of the three trisomies.
1. Down's: flat facies, epicanthal folds, simian crease

2. Edward's: micrognathia, lowset ears, clenched hands

3. Patau's: cleft lip/palate, holoprosencephaly, polydactyly
List the chromosomes commonly involved in Robertsonian translocation.
Chromosomes 13, 14, 15, 21, 22

Results in loss of short, 'p' arms of chromosomes, and a giant chromosome
Cri-du-chat syndrome
Presentation and Genetics:
Presentation:

Microcephaly
Moderate to severe MR
Hi pitched, cat-like scream
Congenital VSD
Congenital microdeletion of short arm of chromosome 5 (46, XX/Xy, 5p-)
Williams Syndrome
Presentation and Genetics:
Presentation:

Long, "elfin" facies, MR, hypercalcemia, very friendly and with good verbal skills
Microdeletion of long arm of chromosome 7. Deleted region includes elastin gene.
22q11 deletion of syndromes
Presentation and Genetics:
Variable presentation including:
Cleft palate
Abnormal facies
Thymic aplasia
Cardiac defects
Hypocalcemia

CATCH-22
Due to microdeletion at 22q11

CATCH-22
Vitamin A
3 active forms
Generation in body
(1)
3 active forms are:
retinal
retinol
retinoic acid
(2)
1. Eaten as β-carotenes in green veggies.

2. Esterified in liver to retinol esters.

3. Retinol is secreted from liver and binds to RBP, traveling together to target tissues

4. Retinol is taken up in tissues and irreversibly converted to retinoic acid.

5. Retinoic acid activates gene transcription of protein products.
Physiological Functions of Vitamin A
**Antioxidant!

1. Component of visual pigments.
2. Important in normal cell differentiation; prevents squamous metaplasia
3. Bone and tooth development.
Vitamin A
Deficiency & Excess
Deficiency results in night blindness, dry skin
Excess results in:

Arthralgias, fatigue, HA, skin changes, sore throat, alopecia.
Di George Syndrome
Presentation & Path:
Pt. will be an infant sick with chronic infections from birth.

Congenital heart defects, esp tetralogy of Fallot, are commonly associated.

Abnormal facies

Hypocalcemia d/t absence of parathyroid glands.
AKA thymic dysplasia, passed on via autosomal dominant inheritance.

Causative mutation results in abnormal development of the 3rd and 4th branchial pouch, so it's often associated with congenital abnormalities and hypoparathyroidism.

Diagnosed by severely decreased T cell count.

Occurs in 50% of patients with 22q11 deletion syndromes.
Velocardiofacial syndrome
Presentation & Path
Presents with palate, facial, and cardiac defects.
Caused by 22q11 mutation. Like DiGeorge's, the branchial arches are affected but unlike DiGeorge's, immunodeficiency is uncommon in these patients.
Vitamin B1
MoA
AKA thiamine or thiamine pyrophosphate (TTP), this nutrient acts as a cofactor in several reactions:

1. Decarboxylation of pyruvate dehydrogenase in glycolysis

2. Decarboxylation of α-ketoglutarate dehydrogenase in the TCA cycle.

3. Transketolase in the HMP shunt

4. Branched-chain AA dehydrogenase.
Vitamin B1
Deficiency & Excess
1. Deficiency results in Impaired glucose breakdown and ATP depletion. Highly aerobic tissues like brain and heart are affected first.

2. Wernicke-Korsakoff syndrome
3. Beriberi
No B1 excess syndromes are known.
Wernicke-Korsakoff syndrome
Presentation &
Path & Etiology:
Wernicke-Korsakoff:

Classic triad of confusion, ophtalmoplegia, ataxia

Also lying, personality change, and memory loss
Caused by thiamine (B1) deficiency

Absence of cofactor for glycolytic, TCA, and HMP reactions decreases aerobic production of ATP.

Highly aerobic tissues are injured first.

Common causes of thiamine deficiency are alcoholism and malnutrition.
Wet vs. Dry beriberi
Presentations
Path & Etiologies
(1)
Wet beriberi: high-output cardiac failure, dilated cardiomyopathy, edema. Hi BP

Dry beriberi: polyneuritis, symmetrical muscle wasting
(2)
Both are caused by thiamine (B1) deficiency.

Common causes of B1 deficiency are alcoholism and malnutrition.
Vitamin B2
MoA
Deficiency
Riboflavin is the precursor to 2 coenzymes in oxidation and reduction reactions: FAD and FMN
Deficiency results in:
1.
Glossitis
Stomatitis
Cheilosis (inflammation of lips, scaling and fissures at the corners of the mouth)

2.
Corneal vascularization
Vitamin B3
Derivatives
MoA
Derived from tryptophan

Synthesis requires B6
Constituent of NAD+ and NADP+

**Remember: Niacin is the layman's nickname for Nicotinamide. NAD = Nicotinamide Adenine Diphosphate.

Niacin is made into NAD!
Vitamin B3
Deficiency & Excess
Deficiency: 3 D's of B3

Diarrhea, Dermatitis, and Dementia

We call B3 deficiency Pellagra, but it usually specifically refers to the "pearl necklace" of niacin deficiency
Excess: facial flusing
Deficiencies of Vitamin B2 vs. B3:
Riboflavin: 2 C's of B2 (plus stomatitis!)

1. Cheilosis (inflammation and scaling of the lips, stomatitis & glossitis)

2. Corneal vascularization
Niacin: 3 D's of B3

Diarrhea
Dermatitis
Dementia
Vitamin B5
(1) MoA
(2) Deficiency
Pantothenate

Essential component of:
1. CoA
2. Fatty acid synthase

**We can't make anything without it!
Deficiency uncommon.

Dermatitis
Enteritis
Alopecia
Adrenal insufficiency

**Rapidly-dividing epithelial cells are injured first!
Vitamin B6
MoA
What do we need it to make?
Pyridoxine

Converted to a cofactor in:

1. Transaminations (AST & ALT)

2. Decarboxylation reactions

3. Glycogenolysis (glycogen phosphorylase)
We need pyridoxine to make:

1. Histamine
2. Pyruvate from serine in gluconeogenesis
3. Niacin from tryptophan
4. Heme
Hartnup disease
Decreased intestinal absorption and renal reabsorption of neutral amino acids.

Results in low tryptophan

Excess tryptophan is normally converted into niacin, therefore low tryptophan = low niacin

Pellagra and B3 deficiency result.
Causes of B3 deficiency:
Deficiency caused by:

1. Malnutrition

2. Hartnup's disease: inability to absorb B3 in intestine and to reabsorb it in urine.

3. Carcinoid Syndrome: b/c its precursor, tryptophan, is instead being made into serotonin!
Vitamin B6 deficiency
Effects:
Causes
1. Sideroblastic anemia
2. Convulsions
3. Peripheral neuropathy
Deficiency can be caused by:

1. Isoniazid
2. Unfortified goat milk.
B12
(1) MoA
(2) Deficiency
Accepts methyl groups from both N5-methyl-TH4 and homocysteine, activating TH4 and deactivating homocysteine!

Therefore, it is necessary for:
1. reducing serum levels of homocysteine, which helps prevent arterial disease.
2. Methylation of dUMP to dTMP.
Cobalamin deficiency results in:

1. Macrocytic, megaloblastic anemia d/t dTTP shortage

2. Atherosclerotic disease d/t homocysteinemia

3.
Neurologic symptoms d/t abnormal myelin
Where do we get our B12?
We get it from animal products, but it is only made by microorganisms.

Most people have a several year storage pool in the liver.
Causes of B12 Deficiency:
1. Malabsorption, i.e.:
Celiac sprue
Enteritis
Diphyllobothrium latum

2. Lack of intrinsic factor, i.e.:
pernicious anenia
gastric bypass
absence of terminal ileum in Crohn's
Distinguishing folic acid deficiency from B12 deficiency
The syndromes are distinct in that there are no neurological symptoms in folic acid deficiency, but many in B12 deficiency.
Causes of folate deficiency:
Most common vitamin deficiency in the U.S.

Usually caused by pregnancy or alcoholism.

Malabsorption disorders
Tapeworm
Chronic pancreatitis

Drugs:
Phenytoin
Sulfonamides
MTX
Biotin
(1) MoA
(2) Deficiency
This nutrient is a cofactor for carboxylation reactions.

Cofactor in the following reactions:

1. Pyruvate carboxylase
2. A.CoA carboxylase
3. Propionyl CoA carboxylase
Dermatitis
Alopecia
Enteritis
Adrenal Insufficiency

**Same as B5, which, not incidentally, also is involved in A.CoA synthesis!
3 Functions of Vitamin C
1. Hydroxylation of Collagen
deficiency = scurvy]

2. Absorption of iron (by reducing it in the gut; Fe3+ can't be absorbed)
[deficiency = microcytic anemia]

3. Necessary for DA beta-hydroxylase to convert DA to NE.
[depression]
In what forms do we take in vitamin D from (1) plants and (2) milk?

What other forms exist in human physiology?
D2 = ergocalciferol, which is ingested from plants

D3 = cholecalciferol
Monohydroxy D3 (25-OH D3): storage form of calciferol

Dihydroxy D3 (1,25-OH D3): active form.
Distinguish mechanisms for conversion to active Vitamin D in endogenous vs. ingested Vitamin D.
Endogenous:

D3 --> 25-OH D3 (liver) --> 1,25-OH D3 (kidney)
Exogenous:

dehydrocholesterol --> Vitamin D3 (photoconversion in skin) --> 25-OH D3 (liver) --> 1,25-OH D3 (kidney)
Vitamin E
Function & Deficiency
Function: Anti-oxidant
Deficiency:

1. Hemolytic anemia d/t radical damage
Vitamin K
MoA:
Deficiency:
Gamma-Carboxylation, i.e. of the coagulation factors!
Increased PT/INR *and* aPTT!!
Vitamin K is necessary for the synthesis of which proteins in the coagulation cascade?
This vitamin is necessary for synthesis of

Clotting factors: 2, 7, 9, 10

Clotting cofactors: Protein C and Protein S
Zinc deficiency:
Deficiency of this nutrient results in delayed wound healing, hypogonadism, decreased growth of adult hair, anosmia and dysgeusia.
Which deficiency/excess of which nutrient causes anosmia and dysgeusia?
Zinc deficiency causes anosmia (lack of smell) and dysgeusia (aberrant sense of taste -- i.e. metallic taste on back of mouth)
Mechanism of ethanol metabolism:
Ethanol --ethanol dehydrogenase--> acetaldehyde --acetaldehyde dehydrogenase--> Acetate
Disulfiram
MoA:
Inhibits acetaldehyde dehydrogenase, increasing acetaldehyde buildup.

Acetaldehyde causes hangover symptoms!
**This drug induces hangover by interrupting the last phase of ethanol breakdown to acetate!
Fomepizole
MoA:
Inhibits alcohol dehydrogenase and is an antidote for methanol or ethylene glycol poisoning.
How does ethanol consumption alter normal glucose metabolism?
Ethanol metabolism causes NADH to build up in the liver. To restore NAD+, we have to reverse 2 major pathways:

Pyruvate ---> Lactate instead of A.CoA

Oxaloacetate ---> malate instead of citrate!
Result:

1. Depletion of pyruvate to make new NAD+ results in decreased gluconeogenesis ---> hypoglycemia!

2. Downregulation of TCA d/t depletion of oxaloacetate
Define marasmus
Energy malnutrition resulting in tissue and muscle wasting, loss of subcutaenous fat, and variable edema.
What metabolic processes occur in the mitochondria?

What processes occur in the cytoplasm?
1. TCA
2. ETC
3. Fatty acid oxidation
4. A.CoA production
1. Glycolysis
2. Fatty acid synthesis
3. HMP Shunt
4. Protein synthesis (RER)
5. Steroid synthesis (SER)
Rate-limiting step of Glycolysis
Fructose-6-phosphate --PFK-1--> Fructose-1,6-phosphate
Rate-limiting step of Gluconeogenesis:
Fructose-1,6-bisphosphonate
Rate-limiting step of TCA cycle:
Isocitrate dehydrogenase
Rate-limiting step of glycogen synthesis
Glycogen synthase
Rate-limiting step of glycogenolysis
Glycogen phosphorylase
Rate-limiting step of HMP shunt
G6PD
Rate-limiting step of de novo pyrimidine synthesis:
Carbamoyl phosphate synthetase II