Genetic Syndromes Flashcards
Rett syndrome
an x-linked disorder that manifests with decreased head circumference velocity and initial failure to gain developmental skills, then progresses to loss of milestones, including speech.
Behaviors include repetitive, purposeless hand movements.
Initial onset is between 6 and 18 months of age.
The majority of children develop epilepsy, often experiencing more than one type of seizure.
Prader-Willi syndrome
genetic syndrome that presents with hypotonia, failure to thrive due to poor feeding, developmental delay, and short stature.
Later, the child becomes constantly hungry, often leading to obesity and type 2 diabetes.
these children are frequently infertile.
Turner syndrome
occurs in girls and is related to the full or partial absence or alteration of one of the X chromosomes. The classic physical findings are short stature, neck webbing, and low-set ears.
cannot reproduce without assistive reproductive technology and usually have average intelligence.
Klinefelter syndrome
only occurs in males and is usually diagnosed at an older age due to a delayed onset of puberty. This syndrome is caused by the presence of two or more XX chromosomes; if three or more X chromosomes are present, the symptoms are usually more severe.
Fragile X
most common inherited cause of intellectual disability
caused by trinucleotide repeat expansion (CGG) within the FMR1 gene
females more mild. most males will present with intellectual disability in the mild-to-severe range
physical phenotype is less apparent prior to puberty but includes: protuberant ears, long thin face, prominent jaw and forehead
Williams syndrome
caused by microdeletion on chromosome 7 at 7g11 and is found in 1 in 7,500 children
associated with heart disease in 80% (usually supravalvar aortic stenosis)
characteristic facial features of periorbital fullness, short nose with bulbous nasal tip, long philtrum, wide mouth, full lips and mild micrognatha
have developmental delays and 75% have intellectual disability
what IQ level is consistent with mild intellectual disability?
50-55 to approximately 70
what IQ level is consistent with moderate intellectual disability?
35-40 to 50-55
what IQ level is consistent with severe intellectual disability?
20-25 to 35-40
what IQ level is consistent with profound intellectual disability?
below 20-25
what is the definition of intellectual disability
cognitive IQ that is 2 standard deviations below the mean (i.e. IQ < 70)
AND
adaptive function that is 2 SD below the mean
what school level can people with mild intellectual disability attain?
6th grade
what school level with moderate ID?
second grade
Down syndrome/Trisomy 21
most common genetic cause of intellectual disability
cause by extra copy of chromosome 21
an x-linked disorder that manifests with decreased head circumference velocity and initial failure to gain developmental skills, then progresses to loss of milestones, including speech.
Behaviors include repetitive, purposeless hand movements.
Initial onset is between 6 and 18 months of age.
The majority of children develop epilepsy, often experiencing more than one type of seizure.
Rett syndrome
