AS: differential diagnosis
| Disorder | Useful investigations | References |
|---|---|---|
| Adapted from Williams CA, et al. Angelman syndrome: mimicking conditions and phenotypes. Am J Med Genet 2001;101:59–64. | ||
| Chromosome disorders | ||
| 22qter deletions involving 22q13.3 | 22qter FISH | Precht et al51 |
| dup 15q11-13 | Chromosome analysis, FISH test | Clayton-Smith et al,52 Repetto et al,53 Schroer et al55 |
| del 2q22-q23 | Microsatellite studies 2q22-23 | Mowat et al62 |
| ZFHX1B analysis | Yamada et al63 | |
| 5p- | FISH | |
| Others: eg 17q23, 4q12, 4p15 | High resolution chromosome studies | Williams et al64 |
| Single gene disorders | ||
| Rett syndrome | MECP2 analysis, EEG. | Laan et al,73 Imessaoudine et al59 |
| Alpha-thalassaemia, retardation syndrome, (ATR-X) | Hb inclusions, mutation/methylation studies of ATR-X gene | Wilkie et al61 |
| Methylenetetrahydrofolate reductase deficiency (MTHFR) | Urine amino acids for homocysteine | Arn et al58 |
| X rays of vertebrae and ilia | ||
| Gurrieri syndrome | Ophthalmological examination | Battaglia and Gurrieri57 |
| Heterogeneous neurodevelopmental disorders | ||
| Cerebral palsy | MRI of the brain | |
| Lennox-Gastaut syndrome | EEG | Laan et al15 |
| Non-progressive encephalopathy | ||
| Childhood autism | ||
| Pervasive developmental disorder | ||
| Mitochondrial encephalopathy | Blood/CSF lactate. MRI of the brain | Nissenkorn et al64 |
| Mitochondrial DNA studies | ||