Features involve head and neck (microcephaly or
macrocephaly, micrognathia, frontal bossing, zygomatic hypoplasia, increased cranial
base angle, hypertelorism, telecanthus, choroid coloboma, hypoplastic alar
cartilage, broad nasal root, short upper lip, median cleft lip, cleft
palate, palatal grooves, alveolar notching, hyperplastic oral frenula,
lobulated/bifid tongue, tongue hamartomas, missing incisor teeth,
supernumerary teeth, periodontal diseases, malocclusion), digits (brachydactyly,
clinodactyly, syndactyly), skin (dry scalp, sparse hair, alopecia), central nervous system
(hydrocephaly, hydranencephaly, porencephaly, partial agenesis of the corpus
callosum, hamartoma of the hypothalamus, gray matter heterotopias,
conductive deafness), and kidneys (renal failure, polycystic kidneys). Mild mental
retardation and irritability occur in 50% of cases. Seizures, precocious
puberty, and short stature can be associated.