Genetic and Congenital Disorders Flashcards
(41 cards)
1
Q
What is a genetic disorder?
A
Discrete event that affects gene expression in a group of cells related to each other by gene linkage
2
Q
What factors can cause genetic disorders?
A
- Genetic factors (single or multi gene disorder or chromosomal abnormality)
- Environmental factor during embryonic or fetal development (maternal disease, infection, drugs taken during pregnancy)
- May show up as “birth defects” or later as congenital disorders
3
Q
What is the difference between genotype and phenotype?
A
GENO: genetic composition
PHEN: observable expression of genotype
4
Q
What does autosomal dominant imply?
A
That each child has a 50% chance of inherting a disorder
5
Q
What does autosomal recessive imply?
A
Each child has 25% chance of being affected, 25% chance of being unaffected, and 50% chance of being a carrier
6
Q
What is Marfan Syndrome?
A
- Autosomal dominant (1/20,000)
- Familial in 75%; rest are result of a mutation in parent’s lifetime
- Affects fibrillin I, a component of extracellular matrix, leading to decreased maintenance of tissue architecture of body structures (ex. tendons, vessels, etc.)
7
Q
What are the manifestations of Marfan Syndrome?
A
- Long thin body and fingers
- Hyper extensible joints
- Kyphosis, scoliosis
- Pectus excavatum (deeply depressed sternum) (pigeon chest)
- Bilateral dislocation of lens (weak ligaments)
- Myopia with predisposition to retinal detachment
- Mitral valve prolapse
- Progressive dilation of aortic valve ring
- Weak aorta and other arteries (dissection, rupture) (increased during pregnancy)
8
Q
What is Neurofibromatosis (NF)?
A
- Neurogenic tumors arising from Schwann cells in peripheral nervous system
- Result of defect in tumor-suppressor gene
- Type NF-1 (Recklinghausen disease) or Type NF-2
9
Q
What is NF-1 also known as? What is it?
A
- Recklinghausen Disease
- Autosomal dominat (50% familial, 50% new mutation)
10
Q
Describe the manifestations of NF-1 (Recklinghausen disease):
A
- Neural tumors on body (sof, pink lesions projecting from skin; firm, round, painful)
- Cafe at lait spots (birth marks) (flat, brown; sharply demarcated edges)
- Lisch nodules on iris (often no problems, but can cause vision problems)
- Scoliosis
- Learning difficulties
11
Q
What is NF-2?
A
- Acoustic nerve tumors
- Multiple intracranial & spinal meningiomas near cranial nerve VIII (Auditory-vestibular nerve)
- Asymptomatic for first 15 years
12
Q
What are the manifestations of NF-2?
A
- Headaches
- Hearing loss
- Tinnitus
- Exacerbated by pregnancy and oral contraceptives
13
Q
What is Phenylketonuria (PKU)?
A
- Autosomal recessive disorder (both parents must have it)
- Elevation of phenylalanine (Amino acid obtained via diet; Usually converted to tyrosine by liver enzyme; Tyrosine assists neurotransmitter and melanin synthesis)
14
Q
What are the manifestations of PKU?
A
- May appear normal at birth; symptoms appear in a few weeks but too late as CNS damage has occurred
- Musty odor to sweat/urine
- Light skin and hair, eczema
- Microcephaly, mental retardation
15
Q
What is the treatment for PKU?
A
- Dietary supplements must being invitro to prevent mental retardation
- Enzyme replacement being developed
16
Q
What is Tay-Sachs disease?
A
- Rare autosomal recessive genetic disorder (Eastern European Jewish population high carrier rate)
- Accumulation of gangliosides in the lysosomes of all organs, predominantly brain and retina neurons
- Results in destruction of neurons
17
Q
What is diagnostic for Tay-Sachs disease?
A
A cherry red-spot on macula, surrounded by white matter
18
Q
What are the manifestations of Tay-Sachs disease?
A
- Infants appear normal at birth
- Progressive weakness, muscle flaccidity appearing at approximately 6 months of age
- Decreased attention span
- Rapid deterioration of motor & mental function, often with generalized seizures after approx. 10 months
- Visual impairment and eventual blindness
- Death by 4-5 years (no cure or tx)
19
Q
What happens with a cleft lip and palate?
A
- Common birth defect/ conspicuous
- Boys > girls (lip and palate)
- Isolated cleft palate more common in girls
- Develops at 35 days gestation
20
Q
What is the etiology of a cleft lip and palate?
A
- Heredary
- Environmental
- Teratogens (ex. rubella, anticonvulsant medications)
21
Q
What are the manifestations of a cleft lip and palate?
A
- Varies (size, involvement of teeth, uni/bilateral)
- Difficulty feeding
- Difficulty vocalizing/speech
22
Q
What is the treatment for a cleft lip and palate?
A
- Plastic surgery (3 months to close lip; 1 year to close palate)
- Dental/Orthodontia work
- Speech therapy
23
Q
What is Down Syndrome? (aka. Trisomy 21)
A
- Most common chromosomal disorder (1/733 births)
- Error in cell division during meiosis resulting in trisomy of chromosome 21
- UKE; aged oocyte
- Obvious manifestations at birth
24
Q
What are the risk factors for Down Syndrome?
A
- Increases with maternal age
- Environmental agents (chemicals, radiation, drugs)
25
What are the manifestations of Down Syndrome relating to the CNS and head/face?
- Mental retardation
- Increased risk of Alzheimer’s disease
- Small, square skull
- Flat facial profile, small nose, depressed nasal bridge
- Eyes: slant upwards, epicanthal fold
- Ears: small, low-set, malformed
- Tongue: large protruding (open mouth)
26
What are the skeletal and CVS manifestations of Down Syndrome?
- Retarded growth
- Hands: short, fingers curled inwards, single palmar crease
- Large space between large and second toe
- Hypotonia, joint laxity
- Fat pad on back of neck
- Congenital heart defects
- GI malformations
- Acute Leukemia
27
What is Turner Syndrome?
- All of part of X chromosome is absent
| - Results in a variation of manifestations in females
28
What are the sexual manifestations of Turner Syndrome in females?
- Lack ovaries (no menstruation)
| - Lack secondary sex characteristics
29
What are the CNS manifestations of Turner Syndrome?
- Visual/spatial disorganization (difficulty driving, doing math, focusing, etc.)
- Strabismus
30
What are the skeletal, CVS and integument manifestations of Turner Syndrome?
- Short, with normal body proportions
- Deformed nail growth; short 4th metacarpal
- Congenital heart defects
- Altered vascular supply to kidneys
- Neck webbing
- Multiple pigmented nevi (moles)
- Lymphedema of hands/feet
31
Describe the diagnosis and treatment of Turner Syndrome:
- Often not noted until late childhood or early adolescence
| - Growth hormone, estrogen therapy, etc.
32
What is Klinefelter Syndrome?
- At least one extra X chromosomes in males (XXY)
| - Often undetected at birth except for smaller penis and small, firm testicles
33
What are the manifestations of Klinefelter Syndrome?
- Gynecomastia
- Sparse facial and body hair
- Small testes (don’t respond at puberty to androgens)
- Inability to produce sperm
- Tall stature at puberty d/t low testosterone levels (lower body longer than upper)
- Female distribution of fat later in life
34
What are the categories of genetic disorders d/t environmental influences?
- General maternal factors
- Teratogenic factors
- Ionizing radiation
- Chemicals
- Drugs
35
What are some general maternal factors that can cause genetic disorders?
- Hormonal balance
- State of health (ex. Measles, DM)
- Nutritional status (ex. Enough folic acid?)
- Medicaions/drugs
36
What is the link between ionizing radiation and genetic disorders?
- Teratogenic and mutagenic
- Possibly effecting inheritable genetics
- No evidence of diagnostic procedures being dangerous
- Microcephaly, skeletal malformations and mental retardation
37
What factors of chemical and drug use are dependent in relation to damage?
- Time of exposure (embryonic/fetal development)
- Length of exposure (time)
- Extent of exposure (dosage)
- Type of chemical/drug (lipid-soluble will cross placenta, small molecular weight cross easily)
38
What is Fetal Alcohol Syndrome?
- Alcohol is lipid-soluble, moderate molecular weight
- Passes freely across placental barrier
- Results in concentration just as high in fetus as in mother
- Effects dependent on time/amount
- Prenatal and/or postnatal growth retardation
39
What are the manifestations of Fetal Alcohol Syndrome?
- CNS abnormalities (devleopmental and intellectual delays)
- Characteristic facial feaures (short nose, small head, thin upper lip, etc.)
- Growth deficits
40
What is Folic Acid Deficiency?
- Implicated in developmental of neural tube defects of brain, spine and spinal cord (anencephaly, spina bifida)
- 400 ug/day recommended during pregnancy
- Dietary sources of enriched cereals; OJ; dark, leafy green vegetables/legumes
41
What are infectous agents causing genetic defects?
- Toxoplasmosis (parasitic infection from undercooked meat/cat feces)
- Rubella (mother infected in first 20 weeks of pregnancy = defects)
- Cytmegalovirus (can lead to retardation)
- Herpes Simplex Virus, type 2 (genital herpes)
