Genetic Conditions Flashcards
Cause: Down syndrome
Trisomy 21
Cause: Klinefelter syndrome
- typically XXY
- can also have additional X chromosomes and more extreme symptoms
- can also have only some cells with extra X chromosomes, and less severe symtpoms (“mosaicism”)
Cause: Turner syndrome
XO (missing X chromosome)
Cause: Tay Sachs Disease
only in Ashkenazi Jewish people
Name: Monosomy X
Turnery Syndrome
Name: Trisomy 18
Edwards Syndrome
Name: Trisomy 21
Down Syndrome
Major cardiac concerns with Marfan syndrome
mitral valve prolapse aortic root dilation
physical characteristics typical of Down Syndrome
- microcephaly
- flattened nose
- appearance of wide-set eyes d/t flattened nose
- protruding tongue
- inner epicanthal folds
- upward slanting eyes (upward slanting palpebral fissures)
- small mouth
- small ears
- short broad hands/fingers
- single palmar crease
- delayed growth/development
- hypotonia
- brushfield spots
- deep plantar groove between 1st and 2nd toes
term for single palmar crease
name this phenomenon
Brushfield spots
describe the epicanthal folds in a child with Down Syndrome
upper eyelid skin fold covers inner corner of eye
Medical Concerns with Down Syndrome
- obesity
- leukemia
- early dementia
- hearing/vision impairment
- seizures
- congenital heart disease
- endocrine abnormalities (diabetes, Thyroid disease)
- esophageal/duodenal atresia
- atlanto-axial instability (C1/C2)
key physical findings with Down Syndrome
- hypotonia
- Brushfield spots
What are the implications for hypotonia with Down Syndrome?
- difficulty with feeding (suck and swallow)
- risk for constipation
Who should be offered genetic evaluation?
- advanced PARENTAL age (over 35)
- miscarriage history
- fhx of genetic defects or MR
- maternal medications, drug use
- certain ethnic groups
INCIDENCE: Down Syndrome
1:660
What is Atlanto-Axial instability?
Who is at higher risk for this, and what are the implications?
neck instability between C1 and C2
get an X-ray of C-spine during sports physical, as this can make the neck in Down’s Syndrome patients less stable than others
INCIDENCE: Klinefelter syndrome
1:1000 males
When does Klinefelter syndrome present?
- typically puberty
- sometimes for workup for infertility
Physical features of Klinefelter syndrome
- hypogonadism
- underdeveloped secondary sex characteristics
- less body hair
- tall stature
- abnormal proportions
- wide hips
- long legs
- gynecomastia
- learning disability
- personality impairment
Medical Concerns with Klinefelter syndrome
- infertility
- osteoporosis
- autoimmune disorders (e.g. lupus)
- learning disabilities (e.g. ADHD, dyslexia)
- autism spectrum disorders
- depression
When does Turner syndrome present?
- often during genetic screening
- during anatomy ultrasound in utero (fluid/webbing of neck)
- but can be during physical exam
INCIDENCE: Turner syndrome
1:2000 (half as common as Klinefelter syndrome)
Key medical issues with Turner syndrome
- COA = coarctation of aorta
- bicuspid aortic valve
- hypertension
**many times, we find COA and it leads us to Turner syndrome
Physical features of Turner syndrome
- lymphedema
- more “coarse” features
- webbed neck
- low hairline
- learning disabilities
- lack of secondary sex characteristics
- shield shaped chest; widely-spaced nipples
- head/neck abnormalities
Major concern with Marfan syndrome
- aortic aneurysm
- aortic regurgitation
- mitral valve prolapse
Physical characteristics of Marfan syndrome
- tall
- wide arm span (exceeds height)
- long narrow face
- pectus carinatum or excavatum
- hyperextension of joints
- genu recurvatum
- kyphoscoliosis
- high arched narrow palate
- dislocated lens (ectopia lentis)
- iridodonesis (lens of eye moves/vibrates with eye movement)
Who is at risk for Marfan syndrome and why?
descendants and parents of patients with Marfan syndrome; it is an inherited autosomal dominant disorder (that does not skip generations)
What can cause palpitations with Marfan syndrome?
mitral valve prolapse or regurgitation
Medical concerns with Marfan syndrome
- detatched retina
- dislocated lens
- aortic aneurysm
- aortic regurgitation –> cardiomyopathy –> heart failure
- mitral valve prolapse
- mitral valve regurgitation
- spontaneous pneumothorax
INCIDENCE: Marfan syndrome
1:10,000 - 1:20,000
INCIDENCE: Tay-Sachs Disease
1:2500 live births
What groups of people are more commonly affected by Tay-Sachs Disease?
- Ashkenazi Jews
- French-Canadians
When does Tay Sachs disease commonly present? How does it present?
3-6 months (normal at birth) with loss of muscle tone
Typical progression of Tay-Sachs Disease
- decreased muscle tone
- cherry red macula
- listlessness
- blindness
- deafness
- seizures
- dementia
- vegetative state
- death
What is a cherry red macula and how is it found?
- found via fundoscopic exam
- concentrated red spot on the macula (in the eye)
What is VCF?
Velocardiofacial Syndrome (DiGeorge Syndrome)
What does DiGeorge Syndrome affect?
- thymus
- parathyroid
- conotrncal region of heart
What is the genetic issue with DiGeorge Syndrome?
22q11.2 deletion
Why are patients with DiGeorge Syndrome at an increased risk of infection?
thymus aplasia (failure to develop normally)
physical characteristics of DiGeorge Syndrome
- lateral displacement of inner canthi
- short plapebral fissures (short eye openings)
- long face
- enlarged (bulbous) nose tip
- short or flattened philtrum
- micrognathia (lower jaw smaller than normal)
- ear anomalies
- cleft palate, possibly cleft lip
What causes an infant with DiGeorge Syndrome to have seizures?
hypoparathyroidism with hypocalcemia
Major medical concerns with DiGeorge Syndrome
- cardiac abnormalities
- seizures due to hypocalcemia from hypoparathyroidism
What causes DiGeorge syndrome?
- deletion of portion of chromosome 22
- usually spontaneous
- rarely inherited
Name some cognitive/behavioral problems associated with DiGeorge Syndrome
- autism spectrum disorder
- ADHD
- depression and anxiety later in life
- developmental delays
- learning disabilities
Name 3 cardiac defects associated with DiGeorge Syndrome
- VSD
- Tetralogy of Fallot
- truncus arteriosus (one large vessel leading out of heart (as opposed to separate aorta and pulmonary arteries – no clear path from RV to lungs or from LV to aorta…blood from both ventricles mixes and goes to both pulmonary artieries and aorta)
Most common genetic cause for obesity
Prader-Willi Syndrome
common symptoms of Prader-Willi Syndrome in infants
- hypotonia
- girls: underdeveloped/hypoplasia of labia minora/clitoris
- boys: small penis, undescended testes
- narrow temples and nasal bridge
- almond shaped eyes
- mild strabismus
- thin upper lip
- downturned mouth
DEFINE: mosiacism
- 2+ genetically different cells in the body (e.g. Klinefelter XXY in some cells but not all)
- symptoms are typically less than if all the cells had a genetic defect
5p- (5p minus) syndrome is also known as…
Cri-du-chat syndrome
symptoms of Cri-du-chat syndrome
- “cat’s cry” syndrome: high-pitched cry, sounds like that of a cat
- intellectual disability
- delayed development
- small head size (microcephaly)
- low birth weight
- weak muscle tone (hypotonia)
- distinctive facies:
- widely set eyes (hypertelorism)
- low-set ears
- a small jaw
- a rounded face
- congenital heart defects (VSD, PDA, ASD)
LIFE EXPECTANCY with Edwards Syndrome
- lethal for most babies
- 20-30% die w/in 1 month
- very few children survive beyond 1st year (5-10%)
Symptoms of Edwards Syndrome
- physical abnormalities
- weak, fragile
- underweight
- microcephaly
- malformed and low-set ears
- small mouth and jaw (micrognathia)
- cleft lip or palate
- clenched hands, index finger overlapping others
- clubfeet, toes webbed or fused
- severe mental retardation
Internal Organ Abnormalities with Edwards Syndrome
- criptochrodism (undescended testes)
- congenital heart disease
- umbilical or inquinal hernia
- malformed kidneys
Describe this floppy baby
hypotonia
Complications/things to monitor in a patient with Down Syndrome
- CBC (risk for anemia, leukemia)
- heart (risk for congenital defects)
- MSK (atlanto-axial instability)
- endocrine (thyroid, diabetes)
- gastrointestinal atresias
- cataracts
- otitis media
- hip dislocation
- OSA
