A person born with one normal copy and one defective copy is called a carrier. They will produce less α-L-iduronidase than an individual with two normal copies of the gene. The reduced production of the enzyme in carriers, however, remains sufficient for normal function; the person should not show any symptoms of the disease. Mechanisms
The IDUA gene is responsible for encoding an enzyme called alpha-L-iduronidase. Through hydrolysis, alpha-L-iduronidase is responsible for breaking down a molecule called unsulfated alpha-L-iduronic acid. This is a uronic acid found in the GAGs dermatan sulfate and heparan sulfate. The alpha-L-iduronidase enzyme is located in lysosomes. Without sufficient enzymatic function, these GAGs cannot be digested properly. Diagnosis
Diagnosis often can be made through clinical examination and urine tests (excess mucopolysaccharides are excreted in the urine). Enzyme assays (testing a variety of cells or body fluids in culture for enzyme deficiency) are also used to provide definitive diagnosis of one of the mucopolysaccharidoses. Prenatal diagnosis using amniocentesis and chorionic villus sampling can verify if a fetus either carries a copy of the defective gene or is affected with the disorder. Genetic counseling can help parents who have a family history of the mucopolysaccharidoses determine if they are carrying the mutated gene that causes the disorders. Classification
All members of the mucopolysaccharidosis family are also lysosomal storage diseases. Mucopolysaccharidosis type I (MPS I) is divided into three subtypes based on severity of symptoms. All three types result the absence or decreased functioning of the same enzyme.
This was noted in human tissue in 1974 and in animal models in 1985. In TLE, the sprouting mossy fibres are larger than in the normal brain and their connections may be aberrant. Mossy fibre sprouting continues from one week to two months after injury. : 416–431 Aberrant mossy fibre sprouting may create excitatory feedback circuits that lead to temporal lobe seizures. This is evident in intracellular recordings. Stimulation of aberrant mossy fibre areas increases the excitatory postsynaptic potential response.However, aberrant mossy fiber sprouting may inhibit excitatory transmission by synapsing with basket cells which are inhibitory neurons and by releasing GABA and neuropeptide Y which are inhibitory neurotransmitters. Also, in animal models, granule cell hyper-excitability is recorded before aberrant mossy fibre sprouting has occurred. Diagnosis
The diagnosis of temporal lobe epilepsy can include the following methods: Magnetic resonance imaging (MRI), CT scans, positron emission tomography (PET), EEG, and magnetoencephalography. Imaging
CT scan is useful as the emergency situations when the suspected cause of epilepsy is due to conditions such as intracerebral haemorrhage, or brain abscesses, or when MRI imaging is not readily available or there is any contraindications to MRI such as the presence of cardiac pacemakers or cochlear implants in the subjects body. CT scan also detect some abnormal calcifications in the brain that is characteristic of diseases such as tuberous sclerosis and Sturge-Weber syndrome.