<unk>  can be detected through the following procedures (before it is apparent through physical examination): a biopsy removing a sample of tissue from the liver, genetic testing, molecular analysis of cells and tissues (to determine the presence of a genetic metabolic disorder), enzyme assay, and occasionally a urinalysis to determine if the above-noted compounds are abnormally stored within the body. For a child to suffer from this disease, both parents must be carriers, and both must transmit the mutation to the child. Thus, even in the case where both parents have the mutation, there is only a 25 percent chance their child will inherit the condition. Frequently, parents are given the opportunity to have a DNA screening if they are at high risk, to determine their carrier status before they have children. However, it is also highly recommended to undergo testing even for those parents who do not have a family history of<unk> . Over 95% of the families that have children with<unk>  had no known prior family history of the condition, as the mutation in the HEXB gene does not cause clinical symptoms when only one copy is present, and often passed undetected from one generation to the next Naturally, if an individual carries the mutation, he or she has a risk of transmitting it to the unborn child. Genetic counseling is recommended for those who have the mutation. It is possible for parents who are about to have a child or had a child with<unk>  can have a PGD or PEGD. PEGD is pre-embryonic genetic diagnosis for the parents that would not benefit from a pre-implantation genetic diagnosis because of their religion or negative attitude for the discarding of embryos. PEGD sequences the genome of the embryo to be produced by two parents if they were to conceive a child. If the family has a history of<unk>  it is recommended they have their genome sequenced to ensure they are not carriers or to sequence the genome of their child. Types There are three types of<unk> : classic infantile, juvenile, and adult late onset. Each form is classified by the severity of the symptoms as well as the age at which the patient shows these symptoms. * Classic infantile form of the disease is classified by the development of symptoms anywhere from 2 months to 9 months of age. It is the most common and most severe of all of the forms and will lead to death before the patient reaches the age of three. Infants with this disorder typically appear normal until the age of 3 to 6 months, when development slows and muscles used for movement weaken. Affected infants lose motor skills such as turning over, sitting, and crawling. As the disease progresses, infants develop seizures, vision and hearing loss, dementia, and paralysis. An eye abnormality called a cherry-red spot, which can be identified with an eye examination, is characteristic of this disorder. Some infants with<unk>  may have enlarged organs (organomegaly) or bone abnormalities. Children with the severe form of this disorder usually live only into early childhood. * The juvenile form of the disease shows symptoms starting at age 3 ranging to age 10 and, although the child usually dies by the time they are 15, it is possible for them to live longer if they are under constant care. Symptoms include autism, ataxia, motor skills regression, spacticity, and learning disorders. * Adult onset form of the disease is classified by its occurrence in older individuals and has an effect on the motor function of these individuals. It is not yet known if<unk>  will cause these individuals to have a decrease in their life span. Juvenile and adult onset forms of<unk>  are very rare. Signs and symptoms can begin in childhood, adolescence, or adulthood and are usually milder than those seen with the infantile form of<unk> . As in the infantile form, mental abilities and coordination are affected. Characteristic features include muscle weakness, loss of muscle coordination (ataxia) and other problems with movement, speech problems, and mental illness. These signs and symptoms vary widely among people with late-onset forms of<unk> .
Sandhoff disease
Tay–Sachs disease
Stratton Parker syndrome
Menkes disease
Gerstmann–Sträussler–Scheinker syndrome
Scheie syndrome
Aceruloplasminemia
Batten disease