Genetic Disorders Flashcards
what are the two main categories of genetic disorder
chromosomal abnormalities and gene defects
3 types of chromosomal abnormalities
nondisjunction, deletion, translocation
cell divide unequally
nondisjunction
part of a chromosome is lost
deletion
part of a chromosome becomes detached and reattaches to a completely different chromosome
translocation
3 types of gene defects
autosomal dominant, autosomal recessive, sex-linked
one parent is affected by the gene
autosomal dominant
either parents is a carrier for the disorder
autosomal recessive
abnormal gene is carried on the X chromosome
sex-linked
cri-du-chat is the deletion of the short arm of which chromosome
5
affects nervous system and affects intellect, can have cardiopulmonary components
cri-du-chat
what are the features of cri-du-chat syndrome
Cat-like cry
Microcephaly
Widely spaced eyes
Profound intellectual disability
Hypotonia
Developmental delay
Club feet
Hip dislocation
Joint hypermobility
Scoliosis
what is the cat cry caused by in cri-du-chat syndrome
laryngeal malformation
prader-willi syndrome is due to partial deletion of what
long arm of chromosome 15
prader-willi syndrome
obesity, underdeveloped gonads, short stature, hypotonia and mild/mod intellectual disability, respiratory compromise, gross motor delays
what disorder is characterized as children becoming obsessed with food at 2, even though they typically have feeding difficulties prior
prader-willi syndrome
partial deletion of long arm chromosome 15 inherited from dad
prader-willi syndrome (PWS)
partial deletion of long arm chromose 15 inherited from mother
angelman syndrome
features of angelman syndrome
developmental delays, intellectual disability, ataxia, speech impairments, progressive microencephaly
when do delays typically present for angelman syndrome
6-12 mo
characteristic of happy affect and flapping hand/arm movements, “happy puppet syndrome”
angelman syndrome
how many cases of arthogryposis multiplex congenita (AMC) are cased from a genetic cause
1/3
neuropathic AMC is caused by an abnormality on which chromosome
5
distal AMC is inherited as an autosomal dominant trait with abnormality on which chromosome
9
T/F: AMC is a non-progressive neuromuscular syndrome
T
features of arthrogryposis multiplex congenita (AMC)
multiple joint contractures, misaligned joints, clubfeet, hip dislocation often requiring surgical correction
autosomal dominant disorder of collagen synthesis that affects bone metabolism; brittle bone disease
osteogenesis imperfecta (OI)
a disorder of bone fragility chiefly caused by mutations in COL1A1 and COL1A2 genes that encode type I procollagen
osteogenesis imperfecta (OI)
features of osteogenesis imperfecta (OI)
short stature, bowing of long bones, ligamentous laxity, kyphoscoliosis, weakness, average or abive average intelligence
how many types of osteogenesis imperfecta (OI) are there, which are the most common and which are most severe
7, I and IV, II and III
what type of activities do you want to avoid with pts with osteogenesis imperfecta (OI)
pull to sit –> do ACTIVE exercises, not passive bc do not want to cause a fx
leading inherited cause of intellectual disability
fragile X syndrome (FXS)
how to manage OI
medical (fx mgnt, parent education), surgical (telescoping rods)
the fragile site for fragile X syndrome (FXS) is on the X chromosome which has a gene that encodes for a ______
fragile X mental redardation protein (FMRP)
features of fragile X syndrome (FXS)
intellectual disability, hypotonia, characteristic long and narrow face with a prominent forehead, jaw and ears, joint hypermobility, flat feet, inguinal hernia, pectus excavatum, mitral valve prolapse
as fragile X syndrome (FXS) passes through generation, does it disease worsen or get better
worsen as it is passed on
behavior characteristics of fragile X syndrome (FXS)
short attention span, impulsivity, tactile defensiveness, perseveration of speech
most common single gene defect associated with autism spectrum disorder
fragile X syndrome (FXS)
a neurodevelopmental disorder that almost only affects females
rett syndrome
features of rett syndrome
intellectural disability (severe to profound), ataxia, and growth retardation
mutation to which gene is responsible for development of synaptic connections in the brain that causes problems in rett syndrome
MECP2
what is william’s syndrome characterized by
cardiovascular disease, developmental delays, learning disabilities
first 6 months, infant appears typically developing, followed by decline of skills loss of language and motor skills, loss of hand function, develop hand flapping and mouthing
rett syndrome
see verbal abilities, highly social personalities, and affinity for music
williams syndrome
facial characteristics of william’s syndrome
small upturned nose, long upper lip, wide mouth, small chin, puffy eyes
features of williams syndrome
low birth weight, feeding intolerance, slow weight gain, sensitive hearing, lower muscle tone, joint laxity
22 Q 11.2 deletion is a microdeletion of which chromosome
22
also called digeorge syndrome, velocardiofacial syndrome, opitx G/BBB syndrome
22 Q 11.2 deletion
features of 22 Q 11.2 deletion
heart abnormalities, cleft palate, distinctive facial features, kidney abnormalities, feeding difficulties, hearing loss, short stature
what are kids with 22 Q 11.2 deletion at increased risk for developing
ADHD, ASD and later in life anxiety, depression, bipolar
how many features do you need to have to be diagnosed with VACTERL/VATER Association
3
features of VACTERL
Vertebral defects (misshapen, fused, missing or extra)
Anal atresia (narrowing or blockage of anus)
Cardiac defects (ventricular septal defect, atrial septal defect, tetralogy of fallot)
Tracheo-esophagel fistula
Renal anomalies (missing one or both kidneys)
Limb abnormalities (poorly developed or missing thumbs/radius)
a chromosomal disorder resulting in 47 chromosomes instead of 46
down syndromes (T21)
occurs due to failure of cell division at chromosome pair 21
down syndrome
most to least common chromosome abnormality at 21
Nondisjunction (each cell in the body have 3 copies of chromosome 21)
Translocation (extra chromosome 21, but is is attached or translocated onto another chromosome)
Mosaic (some cells have 3 copies of chromosome 21, some have 2)
what is the most common chromosomal disorder
T21
what factors play a role in increase incidence of T21
maternal age
neurpathology of T21
microcephaly, decreased diameter of head, reduction of secondary sulci, lack of small neurons, abnormalities to pyramidal tracts of motor cortex (difficulties with motor coordination), lack of and delay of myelination (up till age 6)
physical characteristics of T21
brachycephaly, fontanels are large and take longer to close, face has flat contour (undeveloped bones), small nose, eyes appear narrow/slanted eyelids, small mouth, tongue sticking out of mouth, short neck/webbing, small ears, abdominal protuberance, small hands and feet, small pinky fingers that curve in, simian crease in hands, toes are small, wide space between 1st and 2nd toes, short in stature
cardiopulmonary impairments of T21
congenital heart defect, atrioventricular septal defect (hole between pumping chambers or collecting chambers), tetralogy of fallot (VSD, narrowing of passage from R ventricle to lungs, enlarged R ventricle, enlarged aorta)
flattening of the back of the head
brachycephaly
visual deficits T21
myopia, cataracts, strabismus, nystagmus
what percent of children with T21 present with mild to moderate hearing loss
60-80%
MSK impairments T21
decreased growth/slow growth, decreased leg length, decreased metacarpal and metatarsal growth, hypotonia, decreased strength, lig laxity (due to collagen deficit, pes planus, patellar instability, scoliosis, atlantoaxial instability)
what are two hallmarks of T21
hypotonia and ligament laxity
neuromuscular impairments T21
hypotonia (low force production and poor cx of muscles), slow postural reactions (balance limitations, slow reaction time, decreased speed), joint hypermobility (instability, movement anxiety)
other medical issues associated with T21
celiac disease, hypothyroidism, ear canal stenosis, frequent otitis media, airway obstruction/sleep (low tone and large tongue), transesophagela fistual (opening between esophagus and trachea allow fluid to pass into trachea/lungs, ASD
hematologic concerns for T21
polycythemia, macrocytosis, thrombocytopenia, leukopenia
elevated number of RBCs
polycythemia
enlargement of RBCs, associated with hypothyroidism
macrocytosis
decreased number of platelets, can be associated with congenital heart defects
thrombocytopenia
low number of WBCs
leukopenia
two oncological concerns in T21
myelodyplastic syndrome (MDS) and leukemia
precancerous condition, originate in bone marrow, decreased platelet count, increased size RBC, decreased number of RBC
myelodysplastic syndrome (MDS)
what can myelodysplastic syndrome progress to if left untreated
leukemia
cancer of blood cells, blasts cells crowd out the normal bone marrow cells, diagnosis via bone marrow aspirate, can be treated with chemotherapy or bone marrow transplantation
leukemia
how to evaluate cognitive deficits during eval for t21
repetition of instruction, use of visual cues/demonstration, repetition of practice of skills, hand over hand or hand over foot demonstration
standardized test for T21
AIMS, PDMS-2, GMGFM 88, BOT 2
gait of children with T21
wide base of support, toeing out and increased hip ER, increased knee hyperextension, excessive pronation
best standardized test to help with prognosis of T21
GMFM
intervention examples for T21
sensory/tactile input, postural alignment, core strengthening, WB activities to promote joint stability, facilitation of co-cx at joints, gross motor skills/transitions, gait training, orthotic management
gait training with children with T21
increase stride length, weight shifting onto lateral border of feet, improve foot alignment, increase trunk rotation, eccentric control
will excessive pronation in T21 be outgrown on its own
no - will most likely need orthotics
