Neurological Diseases that Often Suffer by Babies – After going through several stages of the screening process, we are finally able to refine the article we have collected with data from reliable sources regarding neurological diseases that often affect babies.
Tay-Sachs disease is a neurological disorder when a deficiency of an enzyme (hexosaminidase A) causes an excessive build-up of certain fats (lipids), known as gangliosides, in the brain and nerve cells.
This abnormal accumulation of gangliosides results in progressive dysfunction of the central nervous system. This disorder is categorized as a lysosome storage disease. The lysosome is the main digestive unit in the cell. The enzymes present in lysosomes break down or digest nutrients, such as certain complex carbohydrates and fats.
When enzymes such as hexosaminidase A, which are needed to break down certain substances, such as fat, are either lost or ineffective, they build up in the lysosomes. This condition is called “ abnormal storage ”. When too much fatty material builds up in the lysosome, it becomes a poison that destroys cells and damages the surrounding tissue.
1. The onset of Tay-Sachs disease is discovered
Tay-Sachs disease is named after the British specialist, Warren Tay (1843-1927). In 1881, he described a patient with a cherry red spot on the retina of his eye, which is a characteristic symptom of this genetic disease.
In addition, Sach’s name comes from the neurologist from New York, United States (US), namely Bernard Sach (1858-1944), whose work a few years later provides the first description of cellular changes in Tay-Sachs disease. He also recognized the familial nature of the disease. Looking at several cases, he noted that the babies with Tay-Sachs disease at the time were of Eastern European Jewish descent.
2. Tay-Sachs disease is caused by a mutation in the HEXA gene
Based on information from NORD, Tay-Sachs disease is caused by a mutation in the alpha subunit hexosaminidase gene (HEXA). The HEXA gene provides instructions for the production of a protein that plays an important role in many bodily functions. When this gene mutation occurs, the protein product may be damaged, inefficient, or absent. Depending on the function of the protein, this can affect many organ systems and the body, including the brain.
The HEXA gene regulates the production of the enzyme hexosaminidase A. More than 80 different mutations of the HEXA gene have been identified in individuals with Tay-Sachs disease.
Inheriting two copies of the HEXA gene mutation (homozygous) results in a deficiency of the enzyme hexosaminidase A, which is needed to break down fatty substances (lipids), known as GM2-gangliosides in the body’s cells. Failure to break down GM2-ganglioside causes an abnormal accumulation in the brain and nerve cells which later leads to progressive damage to the central nervous system.
Changes in the HEXA gene that cause Tay-Sachs disease are inherited in an autonomous recessive manner. Most genetic diseases are determined by the status of two copies of the gene, that is, one from each parent.
A recessive genetic disorder occurs when a person inherits two copies of an abnormal gene for the same trait, one from each parent. However, if a person inherits only one normal gene and one gene for the disease, then that person will become a carrier, which usually will not show symptoms.
The risk of two carrier parents passing on the altered gene and having the affected child is 25 percent with each pregnancy, while the risk of having a child who is a carrier is 50 percent with each pregnancy. The chance for a person to receive a normal gene from both parents is 25 percent in each pregnancy. The risk is the same for women and men.
3. Types of Tay-Sachs disease based on the symptoms that develop
The signs and symptoms of Tay-Sachs disease vary when symptoms first develop. The most common type is infantile Tay-Sachs disease, whose first signs appear between 3 and 6 months of age. Usually parents will start to notice if the child’s development and movements are very slow.
At this stage, your child may not be able to turn over or sit down. If your child is older, they will likely have difficulty crawling or lifting their arms.
In addition, your child may overreact and be surprised to loud noises and may appear lethargic. From there, the deterioration of mental and physical functioning is usually discontinuous and profound. Other symptoms of infantile Tay-Sachs disease include:
- Hearing loss and deafness
- Muscle rigidity and spasticity
- Loss of vision and blindness
- Drooling and difficulty swallowing (dysphagia)
- Muscle atrophy
- Loss of intellectual and cognitive function
Death, even with the best of medical care, usually occurs before 4 years of age.
Apart from infantile Tay-Sachs disease, there are other forms of the disease that are seen less frequently in children and adults. The timing of the disease is largely related to the combination of genes inherited from parents. Two less common forms of Tay-Sachs disease are:
- Juvenile Tay-Sachs disease: this type usually manifests as symptoms from 2 to 10 years of age. Like the infantile Tay-Sachs, the progression of this type of disease persists, leading to deterioration of cognitive skills, speech and muscle coordination, as well as dysphagia and spasticity. Death usually occurs between the ages of 5 and 15 years.
- Late-onset Tay-Sachs disease or adult Tay-Sachs: this type is very rare and usually develops between the ages of 30 and 40. Unlike other types, this type is usually not fatal and will stop growing after some time. During this time, a person may experience decreased mental skills, shakiness, difficulty speaking, dysphagia, spasticity, and even psychoses such as schizophrenia. Patients with this type of Tay-Sachs disease can often be permanently disabled and need full-time wheelchair assistance.