microcephalic

• adj.

• 小頭症の

関

microcephaly, microencephaly

　

WordNet

1. having an abnormally small head and underdeveloped brain; "a nanocephalic dwarf" (同)microcephalous, nanocephalic

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/05/04 21:24:50」(JST)

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"Microcephalus" redirects here. For the genus of beetle, see Microcephalus (genus).

Microcephaly
Neural scans of a person without microcephaly (left) and a patient with microcephaly
Classification and external resources
ICD-10	Q02
ICD-9	742.1
OMIM	251200
DiseasesDB	22629
MedlinePlus	003272
MeSH	D008831

Microcephaly is a neurodevelopmental disorder. It is an important neurologic sign, but no uniformity exists in its definition. It is usually defined as a head circumference (HC) more than two standard deviations below the mean for age and gender. Some academics advocate defining it as head circumference more than three standard deviations below the mean for the age and sex. Microcephaly may be congenital or it may develop in the first few years of life. The disorder may stem from a wide variety of conditions that cause abnormal growth of the brain, or from syndromes associated with chromosomal abnormalities. A homozygous mutation in one of the microcephalin genes causes primary microcephaly.

In general, life expectancy for individuals with microcephaly is reduced and the prognosis for normal brain function is poor. The prognosis varies depending on the presence of associated abnormalities.

Causes

Microcephaly is a type of cephalic disorder. It has been classified in two types based on the onset:

Congenital

Isolated

1. Familial (autosomal recessive) microcephaly
2. Autosomal dominant microcephaly
3. X-linked microcephaly
4. Chromosomal (balanced rearrangements and ring chromosome)

Syndromes

• Chromosomal

1. Down syndrome
2. Edward syndrome
3. Patau syndrome
4. Unbalanced rearrangements

• Contiguous gene deletion

1. 4p deletion (Wolf–Hirschhorn syndrome)
2. 5p deletion (Cri-du-chat)
3. 7q11.23 deletion (Williams syndrome)
4. 22q11 deletion (DiGeorge syndrome)

• Single gene defects

1. Smith–Lemli–Opitz syndrome
2. Seckel syndrome
3. Cornelia de Lange syndrome
4. Holoprosencephaly

Acquired

• Disruptive injuries

1. Ischemic stroke
2. Hemorrhagic stroke
3. Death of a monozygotic twin

• Congenital infections

1. Congenital cytomegalovirus infection
2. Toxoplasmosis
3. Congenital rubella syndrome

• Drugs

1. Fetal hydantoin syndrome
2. Fetal alcohol syndrome

Other

1. Radiation exposure to mother
2. Maternal malnutrition
3. Maternal phenylketonuria
4. Poorly controlled gestational diabetes
5. Hyperthermia
6. Maternal hypothyroidism
7. Placental insufficiency

Postnatal onset

Genetic

• Inborn errors of metabolism

1. Congenital disorder of glycosylation
2. Mitochondrial disorders
3. Peroxisomal disorder
4. Glucose transporter defect
5. Menkes disease
6. Amino acidopathies
7. Organic acidemia

Syndromes

• Contiguous gene deletion

1. 17p13.3 deletion (Miller–Dieker syndrome)

• Single gene defects

1. Rett syndrome (primarily girls)
2. Nijmegen breakage syndrome
3. X-linked lissencephaly with abnormal genitalia
4. Aicardi–Goutières syndrome
5. Ataxia telangiectasia
6. Cohen syndrome
7. Cockayne syndrome

Acquired

• Disruptive injuries

1. Traumatic brain injury
2. Hypoxic-ischemic encephalopathy
3. Ischemic stroke
4. Hemorrhagic stroke

• Infections

1. Congenital HIV encephalopathy
2. Meningitis
3. Encephalitis

• Toxins

1. Lead poisoning
2. Chronic renal failure

• Deprivation

1. Hypothyroidism
2. Anemia
3. Congenital heart disease
4. Malnutrition

A genetic factor may play a role in causing some cases of microcephaly. Relationships have been found between autism, duplications of chromosomes, and macrocephaly on one side. On the other side, a relationship has been found between schizophrenia, deletions of chromosomes, and microcephaly. Moreover, an association has been established between common genetic variants within known microcephaly genes (MCPH1, CDK5RAP2) and normal variation in brain structure as measured with MRI (i.e., primarily brain cortical surface area and total brain volume).

Microencephaly

"Microcephaly" means "smallheadedness" (New Latin microcephalia, from Ancient Greek μικρός "small" and κεφαλή "head"). "Microencephaly" means "small brain". Because the size of the brain is mostly determined by the size of the head, microencephaly is implied when discussing microcephaly.

Other

After the dropping of atomic bombs on Hiroshima and Nagasaki, several women close to ground zero who had been pregnant at the time gave birth to children with microcephaly. Microcephaly prevalence was seven of a group of 11 pregnant women at 11–17 weeks of gestation who survived the blast at less than 1.2 km 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. Microcephaly is the only proven malformation, or congenital abnormality, found in the children of Hiroshima and Nagasaki.

Presentation

Affected newborns generally have striking neurological defects and seizures. Severely impaired intellectual development is common, but disturbances in motor functions may not appear until later in life.

Infants with microcephaly are born with either a normal or reduced head size. Subsequently, the head fails to grow, while the face continues to develop at a normal rate, producing a child with a small head and a receding forehead, and a loose, often wrinkled scalp. As the child grows older, the smallness of the skull becomes more obvious, although the entire body also is often underweight and dwarfed. Development of motor functions and speech may be delayed. Hyperactivity and intellectual disability are common occurrences, although the degree of each varies. Convulsions may also occur. Motor ability varies, ranging from clumsiness in some to spastic quadriplegia in others.

Prognosis

Generally, no specific cure is known for microcephaly. Treatment is symptomatic and supportive.

History

People with microcephaly were sometimes sold to freak shows in North America and Europe in the 19th and early 20th centuries, where they were known by the name "pinheads". Many of them were presented as different species (e.g., "monkey man") and described as being the missing link. Famous examples are Zip the Pinhead (although he may not have had microcephaly) and Schlitzie the Pinhead, who also starred in the 1932 movie Freaks. Both these individuals were cited as influences on the development of the long-running comic strip character Zippy the Pinhead, created by Bill Griffith.

Notable microcephalic persons

• Beetlejuice is a member of Howard Stern's "Wack Pack".
• Triboulet was a jester of kings Louis XII and Francis I of France. He appears in Victor Hugo's Le Roi s'amuse and its operatic version, Giuseppe Verdi's Rigoletto.
• Jenny Lee Snow and Elvira Snow, commonly referred to as Pip and Flip, were sisters with microcephaly who acted in the 1932 film, Freaks.
• Schlitze "Schlitzie" Surtees, possibly born Simon Metz, was a sideshow performer and actor.

See also

• Hydrocephaly
• Macrocephaly
• Seckel syndrome
• Anencephaly

References

External links

• microcephaly at NINDS
• Microcephaly Support Group
• The Rat People of Pakistan
• NINDS Overview
• Schlitzie The Pinhead

UpToDate Contents

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• 1. 幼児および小児における小頭症：病因および評価 microcephaly in infants and children etiology and evaluation
• 2. 新生児における小水疱性および膿疱性の病変 vesiculobullous and pustular lesions in the newborn
• 3. 小頭症に対する臨床遺伝学的アプローチ microcephaly a clinical genetics approach

English Journal

• Zika Virus RNA Replication and Persistence in Brain and Placental Tissue.

• Bhatnagar J, Rabeneck DB, Martines RB, Reagan-Steiner S, Ermias Y, Estetter LB, Suzuki T, Ritter J, Keating MK, Hale G, Gary J, Muehlenbachs A, Lambert A, Lanciotti R, Oduyebo T, Meaney-Delman D, Bolaños F, Saad EA, Shieh WJ, Zaki SR.
• Emerging infectious diseases.Emerg Infect Dis.2017 Mar 15;23(3). doi: 10.3201/eid2303.161499. [Epub ahead of print]
• Zika virus is causally linked with congenital microcephaly and may be associated with pregnancy loss. However, the mechanisms of Zika virus intrauterine transmission and replication and its tropism and persistence in tissues are poorly understood. We tested tissues from 52 case-patients: 8 infants w
• PMID 27959260

• Homozygous variants in pyrroline-5-carboxylate reductase 2 (PYCR2) in patients with progressive microcephaly and hypomyelinating leukodystrophy.

• Meng L1,2, Donti T1, Xia F1,2, Niu Z1, Al Shamsi A3, Hertecant J3,4, Al-Jasmi F3,4, Gibson JB5, Nagakura H5, Zhang J2, He W2, Eng C1,2, Yang Y1,2, Elsea SH1,2.
• American journal of medical genetics. Part A.Am J Med Genet A.2017 Feb;173(2):460-470. doi: 10.1002/ajmg.a.38049. Epub 2016 Nov 11.
• Pyrroline-5-carboxylate reductase 2, encoded by PYCR2, is one of the three homologous enzymes that catalyze the last step of proline synthesis. Homozygous variants in PYCR2 have been reported in patients from multiple consanguineous families with hypomyelinating leukodystrophy 10 (HLD10) (MIM: 61642
• PMID 27860360

• Evaluation of anti-Zika virus activities of broad-spectrum antivirals and NIH clinical collection compounds using a cell-based, high-throughput screen assay.

• Adcock RS1, Chu YK1, Golden JE2, Chung DH3.
• Antiviral research.Antiviral Res.2017 Feb;138:47-56. doi: 10.1016/j.antiviral.2016.11.018. Epub 2016 Dec 3.
• Recent studies have clearly underscored the association between Zika virus (ZIKV) and severe neurological diseases such as microcephaly and Guillain-Barre syndrome. Given the historical complacency surrounding this virus, however, no significant antiviral screenings have been performed to specifical
• PMID 27919709

Japanese Journal

• The origin of Homo floresiensis and its relation to evolutionary processes under isolation

• LYRAS G. A.,DERMITZAKIS M. D.,VAN DER GEER A. A. E.,VAN DER GEER S. B.,DE VOS J.
• Anthropological science : journal of the Anthropological Society of Nippon 117(1), 33-43, 2009-04-01
• … The microcephalic skulls fall within the range of modern humans, as well as the skulls of the Neolithic small people of Flores. …
• NAID 10029566900

• Microcephalic osteodysplastic primordial dwarfism II 型患児に対する日帰り全身麻酔経験

• 湯村 潤子,笠原 正貴,福田 謙一,高北 義彦,田村 洋平,櫻井 誠,金子 完子,一戸 達也,金子 譲
• 日本歯科麻酔学会雑誌 = JOURNAL OF JAPANESE DENTAL SOCIETY OF ANESTHESIOLOGY 34(2), 223-224, 2006-04-15
• NAID 10018114126

Related Pictures

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★リンクテーブル★

リンク元	「microencephaly」

「microencephaly」

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小頭症

関

microcephalic、microcephaly