Evaulation Of GDD/ID Flashcards
What percent of the population have GDD/ID
3%
What percent of GDD/ID have an identifiable etiology?
40-80%
- 80% in severe ID
- 24% mild ID
What are the benefits of diagnosis in GDD/ID
- timely initiation of treatment and supportive management
- Prevention of complications
- Improved prognostication
- Accurate genetic counselling
- Better access to community services
- Resolution of diagnostic odyssey and avoidance of unneeded tests
What are the diagnostic criteria for GDD?
Significant (<2SD below mean) in >2 developmental domains
- Gross or fine motor
- Speech and language
- Cognition
- Social/personal
- ADLs
Age <5yo
What are the diagnostic criteria for ID
3 criteria must be meet
- deficits in intellectual function (reasoning, problem solving, planning, abstract thinking, judgement, academic learning) confirmed on clinical assessment and intelligence testing
- deficits in adaptive functioning that results in failure to be personally independent and socially responsible - requires ongoing support in community, social participation, independent living
- onset during the developmental period
What are causes of GDD/ID
Prenatal intrinsic: genetic, CNS malformation, metabolic
Prenatal extrinsic: teratogens/toxins, infections
Perinatal: asphyxia, prematurity, neonatal complications
Postnatal: neglect, infections, trauma, toxins
What percent of GDD/ID etiology can be diagnosed based on history and physical?
- 5-38.6%
- requires 3 generation Fhx, psychosocial history, prenatal and birth history, and timing of major milestones
What important factors are you looking for in a family history?
Recurrent miscarriages Birth defects Infant deaths GDD/ID Neurologic conditions Genetic conditions Ethnic background Consanguinity
Which 2 test should be ordered immediately for children with GDD/ID
Vision and hearing assessments
What test is considered the single best test for diagnosing GDD/ID? What is it’s diagnostic yield?
CMA
8-20%
Why isn’t karyotype a first line investigation?
Sensitivity is less than half of CMA
When should a karyotype be ordered?
If there’s suspected aneuploidy
What is the most common cause of ID
FXS - males 2-6%, females 1-4%
How common is Rett syndrome? What gene is it? When should it be tested?
1.5% girls with moderate-severe ID
MECP2 gene
If characteristic symptomatology is present OR if female with moderate-severely affected
What percent of causal mutations can WES identify in severe ID?
40%
What are red flags for IEMs
Family history of IEM, DD, unexplained neonatal death or SIDS Consanguinity IUGR FTT HC or height >2SD or <2SD from mean Recurrent vomiting, ataxia, seizures, lethargy, coma Hx of severely symptomatic or needing longer to recover with benign illnesses Unusual dietary preferences Regression Behavioural or psychiatric problems Movement disorder Facial dysmorphism Organomegaly Severe hypotonia Congenital nonfacial anomalies Sensory deficits, esp. if progressive Noncongenital progressive spine deformities Neuroimaging abnormalities
When should metabolic testing be done?
If there is clinical suspicion, absence of neonatal screening or if genetic testing and neuroimaging have not been diagnostic
What is the diagnostic yield of screening metabolic work up
1-5%
What is the diagnostic yield of the TIDE work up - 1st tier testing?
60%
What additional investigations that are not recommended in the tier 1 investigations, but are causes of ID
Hypothyroidism - central or acquired causes
Iron deficiency anemia - hx of pica or feeding restrictions
B12 deficiency
Lead poisoning - if risk factors
Congenital infections - only if neurological anomalies, microcephaly, VL or HL
How many cases have lesions on MRI? What is the diagnostic yield of MRI?
30% have lesions
0.2-2.2% of the time it contribute to the diagnosis
When should MRI and EEG be considered?
- MRI: if abN Neuro exam, seizures, macro/microcephaly, (AAN - if CMA/FXS/Rett testing inconclusive)
- EEG: if clinical suspicion of seizures, speech regression, neurodegenerative disorder
