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61

What is pleiotropy?

One gene causing multiple phenotypic effects

62

Locus vs. allelic heterogeneity?

Locus heterogeneity means that the same phenotype occurs with mutations at different loci. Whereas allelic heterogeneity is the same phenotype occurs with mutations at the same loci.

63

Heteroplasmy?

Presence of both nl and mut mtDNA. Examples of mitochondrial syndromes are Leber hereditary optic neuropathy, myoclonic epilepsy w/ ragged-red fibers, mitochondrial encephalomyopathy w/ lactic acidosis and stroke-like episodes (MELAS)

64

Uniparental disomy

2 copies of a chromosome from 1 parent; heterodisomy (meiosis I error); isodisomy (meiosis II or later error). Can cause what appears to be imprinting-related disease (Prader-Willi or angelman)

65

Hardy-Weinberg assumptions

No mutations, no natural selection, no migration, random mating

66

What is imprinting?

At some loci, only one allele is active while the other is inactivated/imprinted by methylation.
Prader-Willi - normally maternal imprinting; Disease occurs if PATERNAL gene problem;
AngelMan - nl paternal imprinting; disease occurs if MATERNAL gene problem

67

Example of X-linked dominant disease?

Hypophosphatemic rickets

68

What are the two parts of the pentose phosphate pathway? (And what is its function)

Irreversible oxidative pathway (G-6P ->-> Ribulose-5-phosphate); creates 2 NADPH
Reversible nonoxidative pathway (Ribulose-5-P Fructose-6-P --> Glycolysis)
Function = generate NADPH for synthetic pathways and detox + produce Ribose-5P for nucleotide synthesis

69

Rate limiting step of pentose phosphate pathway?

1st step done by glucose-6-phosphate dehydrogenase

70

G6PD Deficiency

Deficiency in rate-limiting step of pentose phosphate pathway. Decreased production of NADPH. RBC's in particular are vulnerable to oxidative stress (e.g. fava beans, tylenol, primaquine, sulfa, dapsone, DKA). Heinz bodies (denatured hgb). Bite cells from phagocytic removal of Heinz.

71

Sickle cell anemia point mutation?

6th codon of Beta-globin gene: glutamic acid -> valine

72

What vitamin does the WHO recommend administering to those with measles?

Vitamin A

73

Alpha-ketoglutarate dehydrogenase complex requires what coenzymes?

Thiamine, lipoic acid, CoA, FAD, NAD+

74

Presentation of phenylketonuria

Scandinavian descent; Within a year - mental retardation, sz, hyperactivity, gait, postural muscle control, dec. pigmentation, "mousy" odor. There exists maternal PKU where baby is affected.

75

Etio of phenylketonuria

Enzyme phenylalanine hydroxylase (phenylalanine req. BH4-> tyrosine); Tyrosine req. BH4 -> DOPA -> melanine and catecholamines; Tyrosine -> Fumarate -> TCA
OR
Dihydrobuipterin reductase (BH2->BH4) deficiency

76

What are the substrates for gluconeogenesis?

Pyruvate from lactate, glycerol, and glycogenic amino acids

77

How does sucrose/sorbitol get into glycolysis?

Sucrose -> fructose -(fructokinase)> fructose 1-P -(Aldolase B)> Glyceraldehyde -(triokinase)> Glyceraldehyde 3-P

78

Hereditary fructose intolerance?

Aldolase B deficiency - vomiting and hypoglycemia (b/c accumulation of fructose-1-phosphate and depletion of Pi) about 20-30 minutes after fructose intake

79

Essential fructosuria?

Fructokinase deficiency -> secretion into urine of fructose; a benign AR disorder

80

Methionine metabolism?

Methionine to SAM (ATP). SAM to Homocysteine. Homocysteine to Methionine (Homocysteine methyltransferase,B12). Homocysteine to Cystathionine to Cysteine (Cystathionine synthase,B6,serine)

81

Role of leptin

Decreases NPY (appetite stimulant) and stimulates POMC and alpha-MSH to inhibit food intake

82

How is isoniazid metabolized?

Acetylation to N-acetyl-isoniazid in hepatic microsomal system --> urine. "Slow acetylators" exist -> increased risk of side effects

83

How do thiazolidinediones work?

Activate PPAR-gamma, nuclear receptor, that increases transcription of Adiponectin, FA transport protein, insulin receptor substrate, glut-4

84

ADPKD mutation?

PKD1 on chromosome 16 (85%); 16 letters in PK

85

Familial adenomatous polyposis gene v. HNPCC (lynch)

FAP is APC gene on chr 5 (polyp =5); HNPCC = mismatch repair genes (MSH2, MLH1)

86

Familial hypercholesterolemia defect?

Defective/absent LDL receptor; tendon xanthomas (Achilles)

87

Hereditary spherocytosis defect?

Spectrin or ankyrin -> hemolytic anemia (inc. MCHC); tx = splenectomy

88

HD defect

(CAG)n on chromosome 4; (The CAG is hunting 4 cylons.)

89

Marfan syndrome defect

Fibrillin-1.

90

MEN 2A/2B gene

ret