Primary
Simple
	Nonsyndromic: sagittal, coronal, metopic, lambdoid
Compound
	Nonsyndromic: bicoronal
	Syndromic: Crouzon’s disease, Apert’s syndrome, Pfeiffer’s disease, Saethre-Chotzen syndrome
Secondary
Metabolic disorders (e.g., hyperthyroidism)
Malformations (e.g., holoprosencephaly, microcephaly, shunted hydrocephalus, encephalocele)
Exposure of fetus (e.g., valproic acid, phenytoin)
Mucopolysaccharidosis (e.g., Hurler’s syndrome, Morquio’s syndrome)