Genetic Disorders Flashcards

1
Q
  1. Why does familial hypercholesterolemia occur?
  2. What is the deficiency in galactosemia?
  3. Glucose-6-phosphate dehydrogenase deficiency: Inheritance pattern? Associated with?
A
  1. Because reduced synthesis or function of LDL receptors results in reduced LDL uptake and increased synthesis of cholesterol.
  2. Galactose-1-phosphate uridyltransferase resulting in the accumulation of galactose
  3. x-linked; hemolytic anemia from oxidative stress
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2
Q

Marfan Syndrome

  1. Defect is in?
  2. Role of this protein?
  3. Results in?
  4. Clinical manifestation?
A
  1. Extracellular matrix protein fibrillin-1
  2. Important component of microfibril elastic fibers that are abundant in the aorta, ligaments, and ciliary zonules of the eye
  3. Disruption of the assembly of the microfibrils; there is also _excessive TGFb _
  4. tall, long extremities and fingers, lax joint ligaments, deformed chest, _ectopia lentis _(lens out and up), mitral valve prolapse
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3
Q

Ehlers-Danlos Syndrome

  1. Inheritance pattern?
  2. This is a group of disorders associated with defects of what?
  3. Clinical manifestation of classic form?
  4. What occurs in the hypermobility variant?
  5. What is vascular EDS?
  6. What 2 types have a defective conversion of type I procollagen to collagen?
  7. What can occur in other variants?
A
  1. Most are autosomal dominant (some are AR or X-linked)
  2. Structure or synthesis of fibrillar collagen
  3. Skin tends to be hyperextensible and vulnerable to damage from minor trauma and hypermobile joints
  4. the joints are painful and may dislocate
  5. Type III collagen - rupture of the uterus, colon, and large arteries are possible
  6. _Arthrochalasia ED_S and Dermatosparaxsis EDS
  7. diaphragmatic herniation or ocular fragility
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4
Q

Familial Hypercholesterolemia

  1. Mutation of? Result?
  2. Normal LDL clearance mechanism?
  3. Mutated clearance?
  4. Inheritance Pattern?
  5. Treatment?
A
  1. The gene for LDL receptor involved in transport and metabolism of cholesterol –> increase plasma cholesterol–> premature atherosclerosis
  2. Uptake mediated by binding to LDL receptors that recognize ApoB–> taken up into liver –> endosome fuses with the lysosome –> LDL dissociates –> metabolized
  3. NO or LOW uptake of LDL
  4. Autosomal dominant
  5. statins
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5
Q

Tay-Sachs

  1. Also known as?
  2. Deficiency in what enzyme?
  3. Gene location? Inheritance pattern?
  4. Pathogenesis?
  5. What appears in the macula? What happens to neurons?
  6. Symptoms? Age?
A
  1. GM2 Gangliosidosis
  2. Hexosaminidase-alpha
  3. 15q; autosomal recessive
  4. GM2 gangliosides accumulate - particularly in the CNS, ANS, and the Retina
  5. Cherry red spot; lysosomes contain whorls of layers of membranes
  6. Motor and mental deterioration; 6 months
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6
Q

Niemann Pick

  1. Deficiency in? What thus accumulates in lysosomes?
  2. Inheritance pattern?
  3. Type A: Who? What occurs? Presentation?
  4. Type B: presentation? Survival?
  5. What happens to all involved organs?
A
  1. Sphingomyelinase; sphingomyelin
  2. Autosomal recessive
  3. Infants; complete deficiency; excensive CNS involvement, hepatosplenomegaly, and death by age 3
  4. Hepatosplenomegaly, insufficiency, little or no CNS involvement; into adulthood
  5. They become enlarged
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7
Q

Niemann Pick Disease type C

  1. Inheritance pattern?
  2. Mutation of NPC1 (most common) causes?
  3. Mutation of NPC2 causes?
  4. Clinical manifestations?
A
  1. Autosomal Recessive
  2. Impaired regulation of cholesterol in cells
  3. Impaired release of free cholesterol from lysosomes
  4. Neuronal degeneration and hepatosplenomegaly
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8
Q

Gaucher Disease

  1. Inheritance pattern?
  2. Mutation in the gene that codes for what?
  3. Deficiency results in accumulation of ____. Where?
  4. Treatment?
A
  1. Autosomal recessive
  2. Glucocerebrosidase
  3. Glucocerebroside accumulation in lysosomes
  4. recombinant glucocerebrosidase, bone marrow transplantation, and/or gene therapy
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9
Q

Gaucher Disease Type I

  1. Where do glucocerebrosides collect?
  2. What major organ is not involved?
  3. Onset (infant/child/adult/elderly)?
  4. Presentation?
A
  1. Phagocytes of spleen, bone marrow, lymph nodes/tissue
  2. Brain
  3. Adulthood
  4. Hepatosplenomegaly, fatigue, anemia, bleeding, bone pain, and pathological fractures
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10
Q

Gaucher Disease Type II

  1. Where do glucocerebrosides collect?
  2. Age of onset?
  3. Presentation?
  4. Death occurs from?

Gaucher Disease Type III

  1. Similar to type II but?
A
  1. Phagocytes of spleen, bone marrow, lymph nodes/tissue, lung, and CNS
  2. First few months of life
  3. Same as type I but with emphasis on CNS manifestation
  4. Neurologic degeneration and respiratory complication
  5. Age of onset is mid to late childhood and they live until 2nd or 3rd decade
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11
Q

Mucopolysaccharidoses

  1. Lysosomal storage disorder associated with deficiency of?
  2. This results in?
  3. Characteristic presentation?
  4. 2 examples?
A
  1. Degradation of glycosaminoglycans (dermatan sulfate, heparin sulfate, keratin sulfate etc)
  2. HMW glycosaminoglycans accumulate in tissue
  3. Organomegaly and rapid mental deterioration
  4. Hunter and Huler’s syndromes
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12
Q

Hurler’s Syndrome

  1. Inheritance pattern?
  2. Deficiency of? Results in accumulation of?
  3. Presentation?
  4. Age of Death?
  5. “Managed” how?
A
  1. Autosomal recessive
  2. alpha-L-iduronidase; dermatan and heparin sulfate
  3. growth/mental retardation, coarse facial features, skeletal deformities, corneal clouding, and heart disease
  4. 6-10 years old
  5. Enzyme replacement therapy and or bon marrow transplant
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13
Q

Hunter Syndrome

  1. Inheritance pattern?
  2. Deficiency of? Results in accumulation of?
  3. Onset and symptoms?
A
  1. X-linked recessive (males)
  2. Iduronate-2-sulfatase; dermatan and heparin sulfate
  3. Similar to hurlers but milder (no corneal clouding) but death before 15
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14
Q

Von Gierke Disease

  1. Deficiency in? Causes?
  2. Presentation?
  3. Inheritance pattern?
A
  1. Glucose-6-phosphatase - doesnt allow the production of free glucose from glycogen –> hypoglycemia
  2. Glycogen build up in liver: hepatomegaly and kidney
  3. Autosomal recessive
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15
Q

McArdle Disease

  1. Deficiency in?
  2. Results in accumulation of glycogen where?
  3. Presentation?
  4. Inheritance pattern?
A
  1. Muscle phosphorylase
  2. Muscle - myopathic glycogenosis
  3. Painful muscle cramps and weakness (especially following exercise)
  4. Autosomal Recessive
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16
Q

Pompe Disease

  1. Deficiency in?
  2. Where does glycogen deposit? Where is it prominent?
  3. What occurs?
  4. Inheritance pattern?
A
  1. Lysosomal enzyme acid maltase
  2. All organs; heart - cardiomegaly
  3. Death from cardiorespiratory failure by age 3
  4. Autosomal recessive
17
Q

Phenylketonuria

  1. Inheritance pattern?
  2. Mutation in ____ _____ resulting in a failure to convert ___ to ____ in the liver.
  3. This results in high concentrations of what? Why is this bad?
  4. Presentation?
  5. Management?
A
  1. Autosomal recessive
  2. phenylalanine hydroxylase; phenylalanine; tyrosine
  3. Phenylalanine which is neurotoxic and causes progressive cerebral demyelination
  4. Progressive mental deterioration by age 1, seizures, decreased pigmentation, and musty body odor
  5. Low phenylalanine diet
18
Q

Alkaptonuria

  1. Inheritance pattern?
  2. Deficiency of ____ ___ which leads to the ____ metabolism of ____ and ____.
  3. What is ochronosis?
  4. Presentation?
  5. Management?
A
  1. Autosomal recessive
  2. Homogentisic oxidase; incomplete; phenylalanine; tyrosine
  3. Homogentisic acid binds to collagen in the CT and turns the tissue blue-black
  4. destructive ochronotic arthritis of large joints in 3rd decade of life
  5. Control intake of phenylalanine and tyrosine
19
Q

Maple Syrup Urine Disease

  1. Inheritance pattern?
  2. Defects in proteins that make up?
  3. Result?
  4. Presentation?
  5. Management?
A
  1. Autosomal Recessive
  2. Branched chain alpha ketp acid dehydrogenase complex
  3. Accumulation of branched chain amino acids and metabolites in blood, CSF, and urine
  4. Mental and physical retardation and maple syrup odor to urine
  5. Control intake of branched chain amino acids
20
Q

Neurofibromatosis Type I

  1. Inheritance pattern? Chance percent of new mutation?
  2. Mutations to what gene? Gene product?
  3. Function of the gene product?
  4. Major clinical features?
  5. Other associated abnormalities?
A
  1. Autosomal dominant; 50%
  2. NF1; neurofibromin
  3. To downregulate the RAS gene to inhibit cell growth
  4. Neurofibromas (cutaneous, subcutaneous, and plexiform), cutaneous pigmentations (cafe au lait spots), and lisch nodules (asymptomatic)
  5. skeletal disorders may involve erosions, scoliosis, and cysts
21
Q

Neurofibromatosis Type II

  1. Inheritance pattern? New mutation percent?
  2. Gene mutation? Gene product?
  3. Function of the gene product?
  4. Presentation?
  5. What is not present that occured in type 1?
A
  1. Autosomal dominant; 50%
  2. NF2; merlin
  3. Regulates contact inhibition and proliferation of schwann cells
  4. Acoustic schwannomas and meningioma
  5. Lisch nodules
22
Q
  1. What is chromosome painting? Limitations
  2. SKY uses cells in what phase? Screening for?
A
  1. Expands FISH with multiple probes; limited by the availability of flourescent probes that excite at different wavelengths
  2. Metaphase; chromosomal aberrations
23
Q

What is anaphase lag? Result?

A

When one homologous chromosome is left out of the cell’s nucleus reulting in one normal cell and one with monosomy

24
Q

Trisomy 21 - Most common

  1. Results from?
  2. Clinical presentation

Trisomy 13

  1. Result from?
  2. Clinical features?
A
  1. Meiotic nondisjunction
  2. flat face, large tongue, broad nasal bridge, simian crease, mental retardation, heart defects, brushfield spots on periphery of iris
  3. Meiotic nondisjunction
  4. Midline abnormalities - ocular hypotelorism to cyclopia to complete absence of eyes, mental retardation, cardiac/renal defects, cleft lip and palate, polydactyly and rocker bottom feet
25
Q

DiGeorge Syndrome

  1. Also known as? Chromosome?
  2. Results from?
  3. Clinical features?
  4. Can be summed up by CATCH-22: acronym?
  5. Management
A
  1. Congenital thymic aplasia/velocardiofacial synrome; 22q11.2
  2. Most are deletions involving multiple genes (10/15% are familial and autosomal dominant)
  3. Incomplete development of thymus and parathyroid, hypocalcemia, high arched palate, cleft palate, congenital heart defects, due to T cell deficiency - chronic and reccurent infections
  4. Cardiac, Abnormal facies, T cell defect, Cleft palate, Hypocalcemia - 22q11 microdeletion
  5. marrow or stem cell transplant
26
Q

Trisomy 18

  1. Result of?
  2. Clinical Features?
  3. Life Expectancy?
A
  1. Mostly meiotic nondisjunction
  2. Microcephaly, malformed ears, cleft lip, clenched hands, heart and kidney defects
  3. 95% spontaneously abort and 905 die within the first year
27
Q

Klinefelter Syndrome

  1. Major karyotype? Condition of ___ hypogonadism.
  2. 55% occur from? 45% occur from?
  3. Clinical characteristics?
  4. Management?
A
  1. 47 XXY; male
  2. Maternal nondisjunction; paternal nondisjunction
  3. tall, small testes, hypogonadism, lack of secondary male characteristics, decreased testosterone, infertile, mild delay in neurologic development but NO mental retardation
  4. testosterone supplements
28
Q

Turner Syndrome

  1. Karyotype? Characterized by?
  2. What happens to the chromosome?
  3. Clinical characteristics?
  4. Management?
A
  1. 45, X; hypogonadism in phenotypic females
  2. Most due to loss of paternal X (others have XX but abnormal one or mosaic)
  3. Short, lymphedema, webbed neck, widely spaced nipples, gonadal dysgenesis, aortic coarctation, low posterior hairline, NO mental retardation
  4. Estrogen and thyroid hormone replacement
29
Q
  1. What is a true hemaphrodite? Chromosomes? External Genetalia?
  2. Male pseudohermaphrodite: Genotypically ____ but phenotypically _____
A
  1. Histologic presence of both ovarian and testicular tissue; both X and Y; ambiguous
  2. male; female
30
Q

Single Gene Disorders and Non-mendelian inheritance: 4 category classification?

A

Triplet Repeat Mutations

Mitochondrial Gene mutations

Genomic Imprinting

Gonadal mosaicism

31
Q

Fragile X

  1. Second most common genetic cause of?
  2. Pattern of transmission?
  3. Father is an affected male: who in offspring are affected? Carriers? No disease?
  4. Clinical features?
  5. Repeat? Gene? Amount to represent full mutation?
A
  1. Mental retardation
  2. X linked recessive
  3. A: none C: daughters N: sons
  4. Males are mentally retarded and present with macro-orchidism; 50% of carrier females may also demonstrate retardation
  5. CCG; FMR-1; 200+
32
Q

Myotonic Dystrophy

  1. Inheritance pattern?
  2. Repeat? What gene?
  3. Clinical characterization?
A
  1. Autosomal dominant
  2. CTG; myotonin protein kinase gene
  3. muscle weakness and wasting, slow nerve conduction velocities, cataracts, testicular atrophy, and baldness in men
33
Q

Huntingtons

  1. Inheritance pattern? Repeat? Gene?
  2. Huntington gene with repeats may inhibit up-regulation of ___ - ____ ____ factor which is needed for?
  3. Clinical characterization?
A
  1. Autosomal dominant; CAG; IT15]
  2. brain-derived neurotrophic; survival of neurons in the striatum
  3. mental impairment, dysphagia, dysarthria, chorea
34
Q
  1. Leber’s hereditary optic neuropathy: Who is affected? Presentation?
  2. Chronic progressive external opthalmoplegia: Paralysis of? Presentation?
A
  1. Mostly males; bilateral progressive loss of vision with optic nerve atrophy eventually resulting in blindness
  2. Paralysis of one or more of the ocular muscles; bilateral blepharoptosis (drooping of the superior eyelid) with spared vision
35
Q
  1. Cri du chat: presentation?
  2. XXY syndrome: presentation?
  3. _ Adult polysystic kidney disease_: Inheritance? Chromosome? Presentation?
  4. Tuberous sclerosis: Inheritance? Presentation?
  5. Von Hippel-Lindau disease: Inheritance? Presentation? Increased risk of developing what carcinoma?
A
  1. mental retardation, microcephaly, cat-like cry
  2. tall, severe acne, some are violent
  3. Autosomal dominant; 16p; hypertension, hematuria, and palpable renal masses
  4. autosomal dominant; facial angiofibromas, hypopigmented macules, mental retardation, and seizures
  5. Autosomal dominant; hemangioblastomas of the cerebellum, brain stem, or retina and adenomas of liver and kidney; renal cell carcinoma
36
Q

Galactosemia

  1. Inheritance?
  2. Deficiendy in?
  3. Accumulation of?
  4. Presentation?
A
  1. Autosomal recessive
  2. Galactose-1-phosphate uridyl transferase
  3. Galactose-1-phosphate
  4. Failure to thrive, infantile cataracts, mental retardation, cirrhosis, and eventually death
37
Q

Cystic Fibrosis

  1. Inheritance?
  2. Defect?
  3. The normal gene product modulates?
  4. Presentation?
A
  1. Autosomal recessive
  2. Cystic fibrosis transmembrane conductance regulator gene
  3. Mediates the movement of ions across membranes
  4. COPD, pancreatic insufficiency, elevated sweat electrolytes, and males are usually infertile
38
Q

Fabry Disease

  1. Inheritance?
  2. What type of disease is this?
  3. Causes by a deficiency in?
  4. This results in accumulation of?
  5. Presentation?
A
  1. X-linked recessive
  2. Lysosomal storage disease
  3. alpha-galactosidase A
  4. ceramide trihexoside
  5. skin lesions (due to hyperkeratosis) and renal failure early in life
39
Q
  1. Hemophilia A: inheritance? Mutations affect what gene? Presentation?
  2. Lesch-Nyhan syndrome: inheritance? Deficiency in what enzyme? Deficiency of this enzyme reults in impaired….? Presentation?
A
  1. X-linked recessive; Factor VIII; bleeding with minor trauma
  2. X-linked recessive; hypoxanthine-guanine phosphoribosyl transferase; impaired purine metabolism and excess production of uric acid; gout and mental retardation