Neural scans of a normal-sized skull (left) and a case of microcephaly (right) Elderly woman with microcephaly Six microcephalic siblings Microcephaly is a type of cephalic disorder. It has been classified in two types based on the onset: Congenital * Isolated *# Familial (autosomal recessive) microcephaly *# Autosomal dominant microcephaly *# X-linked microcephaly *# Chromosomal (balanced rearrangements and ring chromosome) * Syndromes * Chromosomal *# Poland syndrome *# Down syndrome *# Edward syndrome *# Patau syndrome *# Unbalanced rearrangements * Contiguous gene deletion *# 4p deletion (Wolf–Hirschhorn syndrome) *# 5p deletion (Cri-du-chat) *# 7q11.23 deletion (Williams syndrome) *# 22q11 deletion (DiGeorge syndrome) * Single gene defects *# Smith–Lemli–Opitz syndrome *# Seckel syndrome *# Cornelia de Lange syndrome *# Holoprosencephaly *# Primary microcephaly 4 *# Wiedemann-Steiner syndrome * Acquired * Disruptive injuries *# Ischemic stroke *# Hemorrhagic stroke *# Death of a monozygotic twin * Vertically transmitted infections *# Congenital cytomegalovirus infection *# Toxoplasmosis *# Congenital rubella syndrome *# Congenital Varicella Syndrome *# Zika virus (see Zika fever#Microcephaly) * Drugs *# Fetal hydantoin syndrome *# Fetal alcohol syndrome * Other *# Radiation exposure to mother *# Maternal malnutrition *# Maternal phenylketonuria *# Poorly controlled gestational diabetes *# Hyperthermia *# Maternal hypothyroidism *# Placental insufficiency *# Craniosynostosis Postnatal onset * Genetic * Inborn errors of metabolism *# Congenital disorder of glycosylation *# Mitochondrial disorders *# Peroxisomal disorder *# Glucose transporter defect *# Menkes disease *# Congenital disorders of amino acid metabolism *# Organic acidemia * Syndromes * Contiguous gene deletion *# 17p13.3 deletion (Miller–Dieker syndrome) * Single gene defects *# Rett syndrome (primarily girls) *# Nijmegen breakage syndrome *# X-linked lissencephaly with abnormal genitalia *# Aicardi–Goutières syndrome *# Ataxia telangiectasia *# Cohen syndrome *# Cockayne syndrome * Acquired * Disruptive injuries *# Traumatic brain injury *# Hypoxic-ischemic encephalopathy *# Ischemic stroke *# Hemorrhagic stroke * Infections *# Congenital HIV encephalopathy *# Meningitis *# Encephalitis * Toxins * Chronic kidney failure * Deprivation *# Hypothyroidism *# Anemia *# Congenital heart disease *# Malnutrition Genetic mutations cause most cases of microcephaly. Relationships have been found between autism, duplications of genes and macrocephaly on one side. On the other side, a relationship has been found between schizophrenia, deletions of genes and microcephaly. Several genes have been designated "MCPH" genes, after microcephalin (MCPH1), based on their role in brain size and primary microcephaly syndromes when mutated. In addition to microcephalin, these include WDR62 (MCPH2), CDK5RAP2 (MCPH3), KNL1 (MCPH4), ASPM (MCPH5), CENPJ (MCPH6), STIL (MCPH7), CEP135 (MCPH8), CEP152 (MCPH9), ZNF335 (MCPH10), PHC1 (MCPH11) and CDK6 (MCPH12). Moreover, an association has been established between common genetic variants within known microcephaly genes (such as MCPH1 and CDK5RAP2) and normal variation in brain structure as measured with magnetic resonance imaging (MRI)i.e., primarily brain cortical surface area and total brain volume. The spread of Aedes mosquito-borne Zika virus has been implicated in increasing levels of congenital microcephaly by the International Society for Infectious Diseases and the US Centers for Disease Control and Prevention. Zika can spread from a pregnant woman to her fetus. This can result in other severe brain malformations and birth defects. A study published in The New England Journal of Medicine has documented a case in which they found evidence of the Zika virus in the brain of a fetus that displayed the morphology of microcephaly. Microlissencephaly Microlissencephaly is microcephaly combined with lissencephaly (smooth brain surface due to absent sulci and gyri). Most cases of microlissencephaly are described in consanguineous families, suggesting an autosomal recessive inheritance. Historical causes of microcephaly After the dropping of atomic bombs "Little Boy" on Hiroshima and "Fat Man" on Nagasaki, several women close to ground zero who had been pregnant at the time gave birth to children with microcephaly. Microcephaly was present in 7 children from a group of 11 pregnant women at 11–17 weeks of gestation who survived the blast at less than from ground zero. Due to their proximity to the bomb, the pregnant women's in utero children received a biologically significant radiation dose that was relatively high due to the massive neutron output of the lower explosive-yielding Little Boy. Researchers studied 286 additional children who were in utero during the atomic bombings, and after a year they found these children had a higher incidence of microcephaly and mental retardation. Other relations Intracranial volume also affects this pathology, as it is related with the size of the brain.
symptom of Adenylosuccinate lyase deficiency
symptom of Pyruvate carboxylase deficiency
symptom of Glucose-6-phosphate dehydrogenase deficiency
symptom of Phenylketonuria
symptom of Dubin–Johnson syndrome
complications of Pyruvate carboxylase deficiency
symptom of Beta-mannosidosis
medical cause of Neonatal jaundice