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Flashcards in Diseases Deck (28):
1

Hemophilia:

Inheritance Pattern

Affected Genes/Proteins

Etiology

Presentation

X-linked Recessive

Clotting Factor VIII/IX

Deficiency in clotting factor interferes in normal clotting to prevent bleeding

Recurrent internal and external bleeding episodes. Bruise/Hematoma formation.

2

Fragile X:

Inheritance Pattern

Affected Genes/Proteins

Etiology

Presentation

X-linked Recessive

FMR1

Trinucleotide "CGG" expansion causes failure to express FMRP from FMR1 gene

Autism, mental retardation, elongated face, large or protruding ears, flat feet, larger testes (macroorchidism), low muscle tone

3

Rett Syndrome:

Inheritance Pattern

Affected Genes/Proteins

Etiology

Presentation

X-linked (females only)

MECP2

Loss of MECP2 causes cells in the locus coeruleus to have decreased noradrenergic innervation of the brain, leading to neurodegeneration.

Normal development until 6-18 months, followed by stagnation and regression. Smaller than normal head, hands, and feet. Repetitive hand movements.

4

G6PD:

Inheritance Pattern

Affected Genes/Proteins

Etiology

Presentation

X-linked Recessive

G6PD

G6PD deficiency causes inability of RBCs to respond to oxidative stress due to reduced activity of PPP

Mostly asymptomatic. Hemolytic anemia in response to oxidative stress. Degmacytes and heinz bodies on an RBC smear.

5

Cystic Fibrosis:

Inheritance Pattern

Affected Genes/Proteins

Etiology

Presentation

Autosomal Recessive

CFTR

CFTR is a transmembrane chloride channel. Mutation causes inability of epithelial cells to import Cl-.

Salty tasting skin, failure to thrive, accumulation of thick, sticky mucus, frequent chest infections, coughing or shortness of breath.

6

Sickle Cell Anemia:

Inheritance Pattern

Affected Genes/Proteins

Etiology

Presentation

Autosomal Recessive

HBB -> HbS

Low-oxygen tension promotes red blood cell sickling -> increased red blood cell destruction (anemia) AND blood vessel occlusion

Sickling crises caused by infection, dehydration, acidosis, low oxygen

7

α-Thalassemia:

Inheritance Pattern

Affected Genes/Proteins

Etiology

Presentation

Other: more common in _

Autosomal Recessive

HBA1, HBA2

HBA1/2 deletion -> Decreased alpha-globin production -> excessive beta-chains that form unstable tetramers with abnormal oxygen dissociation curves

Microcytic hypochromic anemia, heinz bodies, splenomegaly

Africans and Asians

8

β-Thalassemia:

Inheritance Pattern

Affected Genes/Proteins

Etiology

Presentation

Other: more common in _

Autosomal Recessive

HBB

HBB deletion -> Decreased beta-globin production -> excessive alpha-chains that bind to and damage RBC membranes

Severe anemia, poor growth, skeletal abnormality during infancy

Africans, Greeks, and Italians

9

Marfan Syndrome:

Inheritance Pattern

Affected Genes/Proteins

Etiology

Presentation

Autosomal Dominant

FBN1

Fibrillin-1 deficiency causes malformation of areas containing elastin fibers (aorta, ligaments, ciliary zonules of eye)

Tall stature. Long, slender limbs and digits. Abnormally flexible joints. Scoliosis. Sunken/raised chest

10

Ehler-Danlos Syndrome:

Inheritance Pattern

Affected Genes/Proteins

Etiology

Presentation

Autosomal Dominant (most types)

Collagen proteins

Mutations cause disruption of the structure, production, or processing of collagen -> weakened connective tissue

Unusually large range of joint movement (hypermobility). Soft, velvety skin that is highly elastic and fragile.

11

Prader-Willi:

Inheritance Pattern

Affected Genes/Proteins

Etiology

Presentation

Not Inherited

Deletion of paternal 15q11-13/Chromosome 15 maternal disomy

Deletion of snoRNA genes

Hypotonia, feeding difficulties, poor growth, and delayed development during infancy. Later: Insatiable appetite -> Hyperphagia and obesity

12

Angelman Syndrome:

Inheritance Pattern

Affected Genes/Proteins

Etiology

Presentation

Not Inherited

Deletion of maternal 15q11-13/Chromosome 15 paternal disomy

Loss of UBE3A gene -> loss of gene product in certain areas of the brain

Delayed development, intellectual disability, severe speech impairment, ataxia, epilepsy, microcephaly

13

Huntington Disease:

Inheritance Pattern

Affected Genes/Proteins

Etiology

Presentation

Other: # repeats = ?

Autosomal Dominant

HTT

Trinucleotide "CAG" expansion -> abnormally long Huntingtin protein that is cut into smaller, toxic fragments that accumulate in neurons

Progressive brain disorder that causes uncontrolled movements (chorea), emotional problems, and loss of cognition

55 = juvenile onset

14

Down Syndrome:

Inheritance Pattern

Affected Genes/Proteins

Etiology

Presentation

Not Inherited

Trisomy 21

Trisomy 21 disrupts normal course of development

Characteristic facial appearance, hypotonia in infancy, cognitive development delays

15

Phenylketonuria:

Inheritance Pattern

Affected Genes/Proteins

Etiology

Presentation

Other: other forms of _ affect other proteins in the _ metabolism pathway

Autosomal Recessive

Phenylalanine hydroxylase, Dihydrobiopterin reductase

Inability to metabolize phenylalanine -> Toxic buildup of phenylalanine in body (particularly neurons)

Infants are fine until toxic levels of Phe build up -> intellectual disability, seizures, delayed development

hyperphe, phenylalanine

16

Ornithine Transcarbamylase Deficiency:

Inheritance Pattern

Affected Genes/Proteins

Etiology

Presentation

X-linked recessive

OTC

OTC mutation -> OTCase deficiency -> orotic acid buildup and hyperammonemia

Symptoms evident within first few days of life: lethargy, poor feeding, poorly controlled breathing rate and body temperature, seizures, coma

17

Xeroderma Pigmentosum:

Inheritance Pattern

Affected Genes/Proteins

Etiology

Presentation

Other: variant can be caused by mutation in _

Autosomal Recessive

Nucleotide excision repair (NER) enzymes

Buildup of unrepaired DNA damage from UV radiation -> cancerous tumors

Severe sunburn after minimal sun exposure, freckling in sun-exposed areas, dry skin, changes in skin pigmentation

error-free polymerase

18

Autism:

Inheritance Pattern

Presentation

Multifactorial

Markedly abnormal or impaired development in social interaction and communication. Symptoms usually appear before age 3

19

Duchenne Muscular Dystrophy:

Inheritance Pattern

Affected Genes/Proteins

Etiology

Presentation

X-linked recessive

DMD

DMD mutation -> dystrophin deficiency -> extensive damage to skeletal and cardiac muscle

Muscle weakness, delayed motor skills, usually wheelchair-dependent by adolescence, cardiomyopathy

20

Patau Syndrome:

Inheritance Pattern

Affected Genes/Proteins

Etiology

Presentation

Not Inherited

Trisomy 13

Trisomy 13 disrupts normal course of development

Severe intellectual disability, heart defects, brain/spinal cord abnormalities, very small eyes, polydactyly, cleft lip

21

Edwards Syndrome:

Inheritance Pattern

Affected Genes/Proteins

Etiology

Presentation

Not Inherited

Trisomy 18

Trisomy 18 disrupts normal course of development

Severe intellectual disability, heart defects, microcephaly, small jaw/mouth

22

Cri du Chat:

Inheritance Pattern

Affected Genes/Proteins

Presentation

Not Inherited

Chromosome 5p deletion

High-pitched sound like a cat, intellectual disability, delayed development, microcephaly, hypertelorism, low-set ears, small jaw

23

Turner Syndrome:

Inheritance Pattern

Affected Genes/Proteins

Presentation

Not Inherited

X0

Short stature, webbed neck, widely-spaced nipples

24

Klinefelter Syndrome:

Inheritance Pattern

Affected Genes/Proteins

Etiology

Presentation

Not Inherited

XXY

Extra copies of X-chromosome interfere with male sexual development

Reduced testosterone production, incomplete puberty, breast enlargement, small testes, infertility

25

Trisomy X:

Inheritance Pattern

Affected Genes/Proteins

Presentation

Not Inherited

XXX

Usually does not cause an abnormal phenotype. Tall stature, learning disabilities, delayed development

26

Retinoblastoma:

Inheritance Pattern

Affected Genes/Proteins

Etiology

Presentation

Autosomal dominant

RB1

Mutations in RB1 (TSG) -> uncontrolled proliferation of retinal cells

Cancer of the retina that usually develops in early childhood. Presents as "cat's eye reflex" (whiteness in the pupil).

27

Bloom Syndrome:

Inheritance Pattern

Affected Genes/Proteins

Etiology

Presentation

Autosomal recessive

BLM

Mutations in BLM -> RecQ helicase deficiency -> increased chromosomal instability -> cancer

Short stature, sun-sensitive skin changes, increased risk of cancer

28

Li Fraumeni Syndrome:

Inheritance Pattern

Affected Genes/Proteins

Etiology

Presentation

Autosomal dominant

CHEK2 and TP53

CHEK2 and TP53 are both TSGs -- mutation causes uncontrolled cell proliferation

Breast cancer, osteosarcoma, soft tissue sarcomas