| Cognitive |
Intellectual disability, usually severe |
Intellectual disability |
Intellectual disability |
| Head |
Macrocephaly (relative) |
Macrocephaly (enlarged skull) with a prominent forehead |
Brachycephaly, frontal bossing |
| |
Upswept frontal hairline |
|
Frontal hair upsweep or low anterior hairline |
| Ears |
Small, underdeveloped ears |
Low set ears with some apparent retroversion |
Low set ears |
| Eyes |
Down-slanting palpebral fissures |
|
Upslanting palpebral fissures |
| |
Widely set eyes (hypertelorism), |
|
Mild hypertelorism |
| Muscle |
Severe hypotonia; |
Hypotonia |
Hypotonia |
| |
A characteristic facial appearance due to hypotonia, giving a droopy, 'open-mouthed' expression |
|
Facial hypotonia with droopy open-mouthed expression |
| |
A thin upper lip, a full or pouting lower lip |
|
|
| Brain |
Partial or complete loss of the corpus callosum |
Partial or complete loss of the corpus callosum |
|
| Cardiac |
Heart defects |
Dilation of the aortic root, ventricular and atrial septal defect |
Some cases with d-TGA, other complex cardiac defects |
| Genitalia |
Cryptorchidism (males) |
Slightly enlarged to normal testicular size in males |
Cryptorchidism or micropenis |
| Chest |
|
Pectus excavatum |
|
| Miscellaneous features unique to each syndrome |
Hyperactive behavior; severe constipation, with or without structural anomalies in the anus such as imperforate anus, broad thumbs and wide first (big) toes |
Maxillary hypoplasia, seizures, Marfanoid habitus |
Autistic and/or hyperactive behavior (not always present) |
