Joubert Syndrome is caused by genetic mutations in which its patients have hypotonia and normal pressure hydrocephalus.
Joubert Syndrome is caused by mutations in ten genes, so how does this happen and what is its relationship to hypotonia and normal pressure hydrocephalus?
An overview of Joubert Syndrome
Joubert Syndrome is an inherited disorder of genetic development that was first identified in 1969. In patients with Joubert syndrome, certain areas of the brain (mainly the cerebellum worm and the brainstem) are underdeveloped or deformed, and this can lead to impairment. Attention, visual, motor, language, and social functional skills.
Causes of Joubert Syndrome
Joubert can be caused by mutations in more than 30 genes. It is known or suspected that the proteins produced from these genes play roles in primary cilia of cells. Mutations in the genes associated with Joubert syndrome lead to problems with the structure and function of the primary cilia, and defects in these cell structure can disrupt important chemical signaling pathways during development.
Specifically, mutations in genes known to be associated with Joubert account for about 60 to 90 percent of all Joubert cases. In the remaining cases, the genetic cause is unknown.
Risk factors
All individuals carry 4 to 5 abnormal genes, so close parents have a higher chance of having children with a recessive genetic disorder than unrelated fathers; Because they both carry the same abnormal gene.
In particular, ten genes have been identified that cause Joubert to mutate, and they are:
JBTS1.
JBTS2.
AHI1 (JBTS3).
NPHP1 (JBTS4).
CEP290 (JBTS5).
TMEM67 (JBTS6).
JBTS7.
JBTS8.
JBTS9.
JBTS10.
Types of Joubert Syndrome
1- Joubert Net
Patients exhibit neurological symptoms of hypotonia, ataxia, and growth retardation differently related to irregular breathing, abnormal eye movements, and intellectual disability. There is no retinal, renal, or hepatic injury. No major gene has been linked to this phenotype, but occasional mutations have been reported in several genes.
2- Joubert with a visual defect
Neurological features of Joubert syndrome are present with retinal dystrophy, including congenital Leber's disease. To date, the gene most mutated in this subset is AHI1, which accounts for about 20% of cases.
3- Joubert with a renal defect
Neurological signs are associated with kidney disease, which in most cases is atrophy of the kidneys, in the absence of retinal injury. The two most common genes for mutation in this rare phenotype are NPHP1 and RPGRIP1L.
4- Joubert with renal visual defect
This type is characterized by linking the neurological signs of Joubert to both retinal atrophy and isotonic hydrocephalus. About 50% of patients carry mutations in the CEP290 gene.
5- Joubert with a liver defect
This type is associated with Joubert's association with chronic liver failure. Colon tumors of retinal choroid neuralgia or coloboma and ischemic hydrocephalus can be part of the phenotype but are not mandatory symptoms. Over 70% of cases are caused by mutations in the TMEM67 gene.
6- Joubert with oral-facial defects
Joubert symptoms are associated with a cleft or lobular tongue (often described as soft tissue nodules or multiple hemangiomas), with a Y-shaped gland of the hand, and the pituitary gland may also be part of this spectrum. This phenotype has recently been associated with mutations in the TMEM216 gene.
Symptoms of Joubert Syndrome
Typically, individuals suffering from Joubert develop:
Ataxia.
Deformed faces.
Delayed development.
Hypotonia.
Rapid breathing.
Impairment of motor performance.
Impaired mental function with an IQ of between 30 and 80.
Difficulty with speech and movement.
Nystagmus.
Joubert Syndrome is caused by recessive gene mutations, so it is recommended to undergo the necessary tests before marriage, especially for relatives. To detect its presence.
