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which layer is affected if you have congenital scoliosis?
mesoderm
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2 causes of congenital scoliosis (what's going on in the vertebrae)
- vertebral formation failure: hemivertebrae or wedged vertebraevertebral
- segmentation failure: the vert don't seperate properly --> a bar w
- no growth plate or disk btwn vertebrate - it's a failure of
- resegmentation of sclerotomes
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lat, ant, post vertebral deformities lead to what?
- lat --> scoliosis
- ant --> kyphosis
- post --> lordosis
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some non-obvious signs of congenital scoliosis
- patch of hair on back
- midline skin hemangioma
- congenital heart defects
- kidney defects
- LLD
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congenital scoliosis may co-exist w a syndrome such as VACTERL which stands for what?
(you should memorize what each letter stands for)
- V: vertebral abnormalities
- A: anal atresia: anus doesn't open to outside of body
- C: cardiac defects
- T: tracheal anomalies (ex; tracheoesophageal fistula)
- E: esophageal atresia; esophagus doesn't connect to stomach
- R: renal
- L: limb abnormalities (absent or displaced thumbs, polydactyly, syndactyly, a missing bone in arms or legs)(so if a kid has scoliosis, keep an eye out for this stuff)
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congenital scoliosis exists with what acronym of troubles?
vacterl
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syndactyly
webbed fingers (due to programmed cell death not happening right)most common limb anomaly
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what is the apical ectodermal ridge (AER)?
apex (highest point) of each limb bud
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when does the AER appear for UE & LE?
- ((apical ectodermal ridge - the apex of each limb bud))
- UE limb buds appear at 4th week
- LE limb buds appear 2 days later
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AER secretes what?
fibroblast growth factor
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fibroblast growth factor - secreted by what? what does it do?
- secreted by the AER (apical ectodermal ridge)
- it induces limb growth
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disturbance of limb buds at 4th week, at 5th week, at 8th causes...
- 4th: absent limb
- 5th: partial limb formed
- 8th: teratogens can't cause major limb deficiencies
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creating skeleton in the limbs... - as the limb lengthens ___ bone models undergo___ to form ___
mesenchymal bone ... chondrification ... hyaline cartilage bone
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what's happening in the limbs at the end of week 7?
end of week 7, entire limb is cartilaginous, and there's an embyonic skeleton
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when is the embryonic stage? what happens here?
- weeks 3-8organogenesis (organs develop)bc new structures are
- developing rapidly, this is a very vulnerable time for the embryo, and
- this is unfortunate, since at this stage lots of ladies don't even
- realize they're pregnant
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chromosomes, the healthy numbers cells should contain
- 46 chromosomes - 23 pairs
- 22 pairs are autosomes (body)
- 1 pair are the gender (xx = girl, xy = boy)
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three parts of a chromatid
- p: the short arm
- q: the long arm
- centromere: the middle part, joining the p to q and the chromatid to a sister chromatid
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how to number bands on a chromosome
the higher numbers are further from the centromere
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46XXdel(14)(q23) means what?
there's a girl with 46 chromosomes but a deletion of band 23 on the long arm chromosome 14
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47, XY, +21 means what?
boy with 47 chromosomes, trisomy of chromosome 21
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non-disjunction error
- failure of chromosome pairs to separate properly during cell division -- either the homologous chromosome or sister chromatids fail to separate
- happens during meiosis or mitosis
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global developmental delay
- delay in achieving 2 or more developmental milestones
- motor
- speech
- cognition
- social
- emotional
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syndromes due to numerical abnormalities caused by non-disjunction errors
- Turner's: 45X
- Kleinfelter: 47XXY
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de novo abnormalities
- neither parent has the abnormal gene
- (as opposed to inherited abnormalities)
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3 syndromes w de novo structural abnormalities
- Cri-du-Chat: del chrom 7
- Prader Willi: parental del chrom 15
- Angelman: maternal del chrom 15
- Williams: del chrom 7
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hypotonia - list of diseases associated with this
- genetic syndromes
- neuro diseases
- endocrine disorders
- metabolic diseases
- down syndrome
- cerebral palsy
- spinal muscle atrophy
- and of course, idiopathic
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characteristics of hypotonia
- decreased strength
- delayed motor skill development
- poor attention/motivation
- decreased activity tolerance
- hypermobile joints - increased flexibility
- tendancy to lean on supports
- rounded shoulders
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autosomal dominant disorders - def and 3 examples
- a mutated or abnormal gene from one parent overrides/dominates the matching gene from the other parent
- osteogenesis imprfecta
- congenital myotonic dystrophy
- neurofibromatosis
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biochemical disorders
- metabolism errors caused by metabolic enzyme deficiencies
- phenylketonuria
- lysosomal storage diseases
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autosomal recessive disorders - def and 4 examples
- recessive mutated gene is inherited from both parents
- typically neither parent is affected
- cystic fibrosis
- sickle cell
- spinal muscle atrophy biochemical disorders
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sex linked disorders def, and 2 categories
- associated with the X chromosome
- x-linked recessive: only males are affected, females are carriers
- x-linked dominant: m & f get it
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2 x-linked dominant syndromes
- Fragile X syndrome
- Retts Syndrome
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Retts Syndrome - what kind of syndrome? who gets it?
- X-linked dominant
- almost exclusively females
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Retts Syndrome - it's a mutation on the x chromosome of what gene?
MECP2, which regulates other proteins involved with brain maturation
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how will a kid with Retts Syndrome look in early infancy / when will the symptoms present?
normal, until MeCP2 regulation is needed at 6-18 months, and the the dev suddenly declines
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2 ways to diagnose Retts?
- positive blood test for presence of mutation
- meets diagnostic criteria (has the clinical pic)
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2 ways Retts presents opposite from Autism
- Retts: prefers people to objects
- Retts: enjoys affection
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what clue would make you think a girl has Retts?
- she seems autistic
- (tho the Retts girl will prefer people to objects, and she'll be affectionate)
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head growth in a girl with Retts Syndrome?
- normal circumference at birth
- then, slowing of rate of head growth at 2-4 months of age
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Retts Syndrome - essential diagnostic criteria include normal dev til 6-18 months, head growth slows at 2-4 months, and what 3 other symptoms
- MR
- gait abnormalities
- stereotypic hand movements (wringing, washing, clapping, bumping...)
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Retts Syndrome stage I
- between 6-18 months
- subtle slowing of development
- delays in gross motor
- less eye contact
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Retts Syndrome stage II timing and real basic description
- 1-4 years
- gradual loss of acquired skills (loses communication skills & purposeful use of her hands)
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6 features of Retts Syndrome in stage II
- autistic like: loss of spoken language and social interaction
- loss of purposeful hand movement: can't feed, gets stereotypic hand motions
- gait abnormalities: wide BOS, toe walking, ataxia
- slowed head growth: --> microcephaly
- behavior disturbances:
- tremors: .
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Retts Syndrome stage III - when?
- 2-10 yrs, can last for many years or lifetime
- can be a plateau
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Retts Syndrome stage III -- 6 prominent features
- apraxia
- seizures
- communication skills may improve
- motor difficulties
- mod to severe MR
- hyperventilation & breath holding
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Retts Syndrome stage IV - the stage's nickname?
motor deterioration
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Retts Syndrome stage IV - features
- reduced mobility
- muscle weakness
- rigidity, spasticity, dystonia
- neuromuscular scoliosis
- cognition, communication, hand skills typically don't decline
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life expectancy w Retts Syndrome
uncertain beyond 40 yrs
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why do many Retts Syndrome gals get femoral fx
osteoporosis
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what percent of Retts Syndrome girls get scoliosis by 13 y/o?
- 75%
- so conduct a physical exam for this and educate the parents!
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mitochondrial disorders come from who?
the mohter, bc the zygote gets all its mitochondria from the egg
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clinical features of mitochondrial disorders
- CNS & muscle affected bc of large amounts of mitochondria in their tissue
- myopathies, gen weakness, decreased balance
- exercise intolerance
- encephalopathy
- retinal degen
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