Disorder | Clinical features | Targeted tests |
Down syndrome |
| G-banded karyotype analysis |
Fragile X |
| FMR1 DNA analysis |
Rett syndrome |
| MECP2 testing |
Klinefelter syndrome |
| G-banded karyotype analysis |
Prader-Willi syndrome |
| Methylation analysis to detect abnormal parent-specific methylation on chromosome 15q11.2-13 |
DiGeorge (22q11.2 deletion) syndrome |
| FISH for 22q11.2 deletion |
Metabolic disorders |
| Metabolic screening (typically this includes measurement of plasma amino acids, urine organic acids, serum ammonia, and lactate; more selective testing can be performed based on the patient's specific characteristics). Further metabolic testing is guided by a specialist. |
Muscular dystrophy |
| Measure serum creatinine kinase as initial screen; if elevated, perform additional evaluation (refer to UpToDate topics on muscular dystrophy for details). |
Congenital hypothyroidism* |
| Thyroid function tests (serum TSH free T4) |
Lead poisoning¶ |
| Blood lead level |
CMA: chromosomal microarray analysis; CT: computed tomography; DNA: deoxyribonucleic acid; FISH: fluorescence in situ hybridization; FMR1: fragile X mental retardation 1 gene; GDD: global developmental delay; ID: intellectual disability; MECP2: methyl-CpG-binding protein 2 gene; MRI: magnetic resonance imaging; TSH: thyroid stimulating hormone; T4: thyroxine.
* Thyroid testing is recommended routinely for infants and children presenting with ID in countries without newborn screening programs for congenital hypothyroidism. In these areas, unrecognized congenital hypothyroidism is a more common cause of ID. In countries where newborn screening for hypothyroidism is routinely performed, congenital hypothyroidism is an uncommon cause of ID and therefore routine thyroid testing is not necessary for children with ID who lack associated signs and symptoms of hypothyroidism.
¶ Blood lead testing should also be performed if the child has not had prior lead screening. While lead toxicity is an uncommon cause of ID in the United States, children with ID are at increased risk for lead exposure. Case identification is essential to allow for treatment and for evaluation of other children who may have been similarly exposed. Refer to UpToDate content on screening for lead poisoning for further information.Do you want to add Medilib to your home screen?