Isolated microcephaly | Autosomal recessive (multiple types) | Autosomal dominant | X-linked microcephaly | Chromosomal abnormalities and syndromes | Trisomies (eg, 21, 18, 13) | Monosomy 1p36 deletion | Seckel syndrome | Smith-Lemli-Opitz syndrome | Williams-Beuren syndrome (7q11.23 deletion) | Cornelia de Lange syndrome | Miller-Dieker lissencephaly syndrome (17p13.3 deletion) | Wolf-Hirschhorn syndrome (4p deletion) | Cri-du-chat syndrome (5p15.2 deletion) | Mowat-Wilson syndrome | Rubinstein-Taybi syndrome | Aicardi-Goutières syndrome | Cockayne syndrome | Bloom syndrome | Angelman syndrome | | Neuroanatomic abnormalities associated with microcephaly | Neural tube defects (eg, anencephaly, hydranencephaly, encephalocele) | Holoprosencephaly | Atelencephaly (aprosencephaly) | Lissencephaly | Schizencephaly | Polymicrogyria | Pachygyria (macrogyria) | Fetal brain disruption sequence | Metabolic disorders | Maternal diabetes mellitus | Untreated maternal phenylketonuria | Phenylketonuria | Methylmalonic aciduria | Citrullinemia | Neuronal ceroid lipofuscinosis | Environmental causes | Congenital infection (eg, cytomegalovirus, herpes simplex virus, rubella, varicella, toxoplasmosis, HIV, syphilis, enterovirus, Zika virus) | Meningitis | In utero drug or toxin exposure (eg, alcohol, tobacco, marijuana, cocaine, opioid, antineoplastic agents, antiepileptic agents, radiation, toluene) | Perinatal insult (eg, hypoglycemia, hypothyroidism, hypopituitarism, hypoadrenalism) | Anoxia/ischemia | |