Genetic Brain Disorders

Genetics play an all important role in the growth and health of a human being. The presence of a mutated gene or absence of an important gene in one parent, gives a child a 50% chance of inheriting a disorder. Sometimes the mutated gene can lie dormant for generations, only to suddenly manifest in a particular generation. While there are many genetic diseases recorded in medical science, inherited diseases which affect the brain and its functioning are of special concern, with respect to the delicate nature of the body area and the severe complications. In this article, learn more about various genetic brain disorders, based on their prevalence in the general population.

Genetic Disorders of the Brain

Huntington's Disease

Gene	Huntingtin
Statistics	Occurrence of 5-10 cases among 100,000 people. No preference for sex but high prevalence rate among people of Western European ethnicity
Symptoms Occurrence Age	Symptoms usually appear in middle age (35 - 45 years) but early signs can occur in young adults and children
Symptoms	Involuntary, slow and jerky movements (chorea) Difficulty in speaking, psychological problems (depression, insomnia, morbid thoughts, bipolar) Cognitive functions like concentration are hampered
Prognosis	No treatment or cure exists but medications can help ease symptoms and improve quality of life

Description : This disorder affects the brain through damage and destruction of neurons (nerve cells). Presence of an affected or mutated copy of the gene can cause this disorder in an individual. It is genetic in nature, where a child of a Huntington infected parent, has a 50% chance of inheriting it. With 2 infected parents, the risk increases to 75%.

Rett Syndrome

Gene	MECP2, CDKL5(rare), FOXG1(rare)
Statistics	Almost exclusive in occurrence in females. Occurs in every 1 out of 10,000 children
Symptoms Occurrence Age	Early childhood onset between 6-18 months of infancy
Symptoms	Cannot speak Severe muscle coordination problems (walking and balance) Breathing difficulties Social withdrawal, tendency to panic and get anxious Abnormal hand actions (wringing of hands) Fingers and hand muscles will not function properly
Prognosis	There is no cure or treatment, patients will require assisted living throughout their lives. Average life span is mid-forties

Description : This is a developmental disorder, which is often confused with autism and cerebral palsy, due to similar symptoms. It can be genetic or sporadic in occurrence. Skills, abilities and normal functioning behavior patterns are lost or cannot be conducted by the affected individual.

Rare Genetic Brain Disorders

The following disorders are rare or uncommon in occurrence. Some are also classified as hereditary brain disorders in infants and young children.

Aicardi Syndrome

Gene	Exact gene not identified yet
Statistics	Predominant amongst the female gender. Estimated 900 cases exist in the USA
Symptoms Occurrence Age	An affected infant will show symptoms of this syndrome between 3-5 months
Symptoms	Abnormal eye formation and structure Seizures or fits in infants Enlarged ventricles and small-sized brain
Prognosis	Treatment involves handling of seizures. The affected individual's development, both mentally and physically is affected. Expected life span is mid-forties

Description : This syndrome is caused by a defect in the brain structure. An important part of the brain, the corpus callosum is incomplete in formation or absent altogether. In a family, only one individual carries the defective gene.

Joubert Syndrome

Gene	JBTS3, JBTS4 and JBTS5
Statistics	Very rare
Symptoms Occurrence Age	Physical signs appear in infant-hood
Symptoms	Cleft lip Extra digits Abnormal eye and tongue movements Erratic and deep breathing Involuntary movements with poor muscle tone Seizures
Prognosis	The affect of this syndrome on individuals varies. Some can have severe mental and physical retardation, others can have a milder impact on mental and physical abilities. Therapy, both physical and speech is prescribed

Description : This disorder physically affects the cerebellum, such that the cerebellar vermis is absent or damaged and brain stem are deformed. It can be genetic or sporadic in nature. For it to be inherited, the defective gene must be in both parents.

Other disorders are:

• Batten Disease
• Fahr's Syndrome
• Moyamoya Disease
• Gerstmann-Sträussler-Scheinker Syndrome

The outcome for most brain disorders, which are inherited is bleak due to lack or no treatment. Research is being carried out as to determine possible treatments or cures. Genetic screening tests and DNA analysis is recommended for individuals, with a familial risk of having a genetic disease.