| 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 | |
