which layer is affected if you have congenital scoliosis?
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
lat, ant, post vertebral deformities lead to what?
- lat --> scoliosis
- ant --> kyphosis
- post --> lordosis
some non-obvious signs of congenital scoliosis
- patch of hair on back
- midline skin hemangioma
- congenital heart defects
- kidney defects
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)
congenital scoliosis exists with what acronym of troubles?
webbed fingers (due to programmed cell death not happening right)most common limb anomaly
what is the apical ectodermal ridge (AER)?
apex (highest point) of each limb bud
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
AER secretes what?
fibroblast growth factor
fibroblast growth factor - secreted by what? what does it do?
- secreted by the AER (apical ectodermal ridge)
- it induces limb growth
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
creating skeleton in the limbs... - as the limb lengthens ___ bone models undergo___ to form ___
mesenchymal bone ... chondrification ... hyaline cartilage bone
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
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
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)
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
how to number bands on a chromosome
the higher numbers are further from the centromere
46XXdel(14)(q23) means what?
there's a girl with 46 chromosomes but a deletion of band 23 on the long arm chromosome 14
47, XY, +21 means what?
boy with 47 chromosomes, trisomy of chromosome 21
- 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
global developmental delay
- delay in achieving 2 or more developmental milestones
syndromes due to numerical abnormalities caused by non-disjunction errors
- Turner's: 45X
- Kleinfelter: 47XXY
de novo abnormalities
- neither parent has the abnormal gene
- (as opposed to inherited abnormalities)
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
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
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
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
- metabolism errors caused by metabolic enzyme deficiencies
- lysosomal storage diseases
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
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
2 x-linked dominant syndromes
- Fragile X syndrome
- Retts Syndrome
Retts Syndrome - what kind of syndrome? who gets it?
- X-linked dominant
- almost exclusively females
Retts Syndrome - it's a mutation on the x chromosome of what gene?
MECP2, which regulates other proteins involved with brain maturation
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
2 ways to diagnose Retts?
- positive blood test for presence of mutation
- meets diagnostic criteria (has the clinical pic)
2 ways Retts presents opposite from Autism
- Retts: prefers people to objects
- Retts: enjoys affection
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)
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
Retts Syndrome - essential diagnostic criteria include normal dev til 6-18 months, head growth slows at 2-4 months, and what 3 other symptoms
- gait abnormalities
- stereotypic hand movements (wringing, washing, clapping, bumping...)
Retts Syndrome stage I
- between 6-18 months
- subtle slowing of development
- delays in gross motor
- less eye contact
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)
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: .
Retts Syndrome stage III - when?
- 2-10 yrs, can last for many years or lifetime
- can be a plateau
Retts Syndrome stage III -- 6 prominent features
- communication skills may improve
- motor difficulties
- mod to severe MR
- hyperventilation & breath holding
Retts Syndrome stage IV - the stage's nickname?
Retts Syndrome stage IV - features
- reduced mobility
- muscle weakness
- rigidity, spasticity, dystonia
- neuromuscular scoliosis
- cognition, communication, hand skills typically don't decline
life expectancy w Retts Syndrome
uncertain beyond 40 yrs
why do many Retts Syndrome gals get femoral fx
what percent of Retts Syndrome girls get scoliosis by 13 y/o?
- so conduct a physical exam for this and educate the parents!
mitochondrial disorders come from who?
the mohter, bc the zygote gets all its mitochondria from the egg
clinical features of mitochondrial disorders
- CNS & muscle affected bc of large amounts of mitochondria in their tissue
- myopathies, gen weakness, decreased balance
- exercise intolerance
- retinal degen