Joubert syndrome

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Joubert syndrome
Classification and external resources
ICD-10Q04.3
ICD-9742.2
OMIM213300
DiseasesDB30688
 
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Joubert syndrome
Classification and external resources
ICD-10Q04.3
ICD-9742.2
OMIM213300
DiseasesDB30688

Joubert syndrome is a rare genetic disorder that affects the cerebellum, an area of the brain that controls balance and coordination.

Diagnosis[edit]

The disorder is characterized by absence or underdevelopment of the cerebellar vermis and a malformed brain stem (molar tooth sign).[1] The most common features include ataxia (lack of muscle control), hyperpnea (abnormal breathing patterns), sleep apnea, abnormal eye and tongue movements, and hypotonia. Other malformations such as extra fingers and toes, cleft lip or palate, tongue abnormalities, and seizures may also occur. There may be mild or moderate retardation. Joubert syndrome is one of the many genetic syndromes associated with syndromic retinitis pigmentosa.[2] The syndrome was first identified by pioneering pediatric neurologist Marie Joubert in Montreal, Canada, while working at the Montreal Neurological Institute and McGill University.[3]

Treatment[edit]

Treatment for Joubert syndrome is symptomatic and supportive. Infant stimulation and physical, occupational, and speech therapy may benefit some patients. Infants with abnormal breathing patterns should be monitored.

Prognosis[edit]

The prognosis for individuals with Joubert syndrome varies. Some patients have a mild form with minimal motor disability and good mental development, while others may have severe motor disability and moderate mental retardation.

Genetics[edit]

A number of mutations have been identified in individuals with Joubert syndrome (JBTS) which allowed for classification of the disorder into subtypes.

TypeOMIMGeneLocusInheritanceRemarks
JBTS1213300INPP5E9q34.3Autosomal recessiveAlso known as Cerebellooculorenal syndrome 1 (CORS1)
JBTS2608091TMEM21611q12.2Autosomal recessiveAlso known as Cerebellooculorenal syndrome 2 (CORS2)
JBTS3608629AHI16q23.3Autosomal recessive
JBTS4609583NPHP12q13
JBTS5610188CEP290
NPHP6
12q21.32Autosomal recessive
JBTS6610688TMEM678q22.1Autosomal recessive
JBTS7611560RPGRIP1L16q12.2
JBTS8612291ARL13B3q11.1
JBTS9612285CC2D2A4p15.32Autosomal recessive
JBTS10300804OFD1Xp22.2X-linked recessive
JBTS11TTC21B2q24.3
JBTS12KIF715q26.1
JBTS13614173TCTN112q24.11
JBTS14614424TMEM2372q33.1Autosomal recessive
JBTS15614464CEP417q32.2Autosomal recessive
JBTS16614465TMEM13811q12.2Autosomal recessive
JBTS17614615C5ORF425p13.2
JBTS18614815TCTN310q24.1
JBTS19ZNF42316q12.1Autosomal dominant
JBTS20614970TMEM23116q23.1Autosomal recessive

Ciliopathy[edit]

Research has revealed that a number of genetic disorders, not previously thought to be related, may indeed be related as to their root cause. Joubert syndrome is one such disease. It is a member of an emerging class of diseases called ciliopathies.

The underlying cause of the ciliopathies may be a dysfunctional molecular mechanism in the primary cilia structures of the cell, organelles which are present in many cellular types throughout the human body. The cilia defects adversely affect "numerous critical developmental signaling pathways" essential to cellular development and thus offer a plausible hypothesis for the often multi-symptom nature of a large set of syndromes and diseases.

Currently recognized ciliopathies include Joubert syndrome, primary ciliary dyskinesia (also known as Kartagener Syndrome), Bardet-Biedl syndrome, polycystic kidney disease and polycystic liver disease, nephronophthisis, Alstrom syndrome, Meckel-Gruber syndrome and some forms of retinal degeneration.[4]

References[edit]

  1. ^ Brancati F, Dallapiccola B, Valente EM (2010). "Joubert Syndrome and related disorders". Orphanet J Rare Dis 5: 20. doi:10.1186/1750-1172-5-20. PMC 2913941. PMID 20615230. 
  2. ^ Saraiva, JM; Baraitser, M (1992). "Joubert syndrome: a review". American Journal of Medical Genetics 43 (4): 726–731. doi:10.1002/ajmg.1320430415. PMID 1341417. 
  3. ^ Joubert M, Eisenring JJ, Robb JP, Andermann F (September 1969). "Familial agenesis of the cerebellar vermis. A syndrome of episodic hyperpnea, abnormal eye movements, ataxia, and retardation". Neurology 19 (9): 813–25. PMID 5816874. 
  4. ^ Badano, Jose L.; Norimasa Mitsuma, Phil L. Beales, Nicholas Katsanis (September 2006). "The Ciliopathies : An Emerging Class of Human Genetic Disorders". Annual Review of Genomics and Human Genetics 7: 125–148. doi:10.1146/annurev.genom.7.080505.115610. PMID 16722803. Retrieved 2008-06-15. 

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