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Tay-Sachs, Canavan, Sandhoff, GM1 and related diseases

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Overview

Sandhoff is a progressive neurological genetic disorder caused by the absence of a vital enzyme.  It is one of over 50 genetically inherited disorders known as Lysosomal Storage Diseases.

There are 3 forms of Sandhoff

alt Infantile Sandhoff - Symptoms appear around 6 months of age.

alt Juvenile Sandhoff - Symptoms appear after the first year of life, typically between ages 2 and 5, but can occur anytime during childhood.

alt Late Onset Sandhoff - Symptoms typically appear in adolescence or early adulthood, but sometimes later.

Who is at risk?

Anyone can be a carrier of Sandhoff. When both parents are carriers, each child has a 25% of having the disease. The carrier rate for the general population is low, approximately 1/600 and it is not yet clear whether Sandhoff disease is more common in any particular population, but may have a higher carrier rate in several somewhat isolated populations. Talk to your doctor about Genetic Counseling to discuss your options before starting your family.

Explore More

altSupport for Families - Resources collected specifically for families

altCauses- Sandhoff is caused by the absence of two vital enzymes: Hexosaminidase A (HexA) and Hexosaminidase B (HexB).

altResearch - To date, there is no treatment or cure for Sandhoff disease but there is exciting ongoing research.

altHistory of Sandhoff - The disease is named for Konrad Sandhoff, a German chemist.

altInfantile & Juvenile Support

altLate Onset Support

 

Symptoms of Infantile Sandhoff

First signs - A baby with Classic Infantile Sandhoff appears normal at birth and typically develops normally for the first six months of age. As development slows, parents may notice a reduction in vision and tracking. The baby does not outgrow normal startle response.

Gradual loss of skills - Infantile Sandhoff children gradually regress, losing skills one by one and eventually are unable to crawl, turn over, sit or reach out.  Other symptoms include loss of coordination, progressive inability to swallow and difficulty breathing.

By Age 2 and beyond - Most children experience recurrent seizures by age 2 and eventually lose muscle function, mental function and sight, becoming mostly non-responsive to their environment.

Diagnosis

Sandhoff disease is diagnosed through a blood test to check the levels of Hexosaminidase A (HexA) and Hexosaminidase B (HexB). A follow-up DNA test may be recommended.  Any doctor can order the Tay-Sachs HexA blood test. Often, diagnosis is made by a neurologist or geneticist.

Babies affected by the infantile form of Sandhoff are frequently diagnosed by the cherry-red spot on the retina of the eye.  Initially many parents notice developmental delays but pediatricians often dismiss these concerns by stating "every baby develops differently" and "the baby will catch up". Often at about 10-14 months of age, children may start to exhibit trouble tracking and/or focusing with their eyes, so parents schedule an appointment for an eye exam.   The cherry-red spot is quickly seen and an initial diagnosis of Sandhoff disease is made.

Diagnosis can also be made by a neurologist or geneticists and the completion of a metabolic evaluation.

Management

There is no treatment or cure for Sandhoff disease but there are ways to manage symptoms. These range from life extending interventions like a feeding tube to comfort measures like massage to promote relaxation.

Respiratory health and seizure management are the two main symptom management challenges in Infantile Sandhoff.

Support

For family resources and recommendations for managing the symptoms, visit Infantile & Juvenile Support

Newly diagnosed families should read Finding Your Philosophy of Care, available through NTSAD. It will help parents develop a care plan and care goals to aid in major care choices.

 

Symptoms

First signs - Early symptoms of Juvenile Sandhoff include lack of coordination or clumsiness and muscle weakness such as struggling with stairs. A child may also exhibit slurred speech, swallowing difficulties and muscle cramps.

Gradual Loss of skills - Over time children with Juvenile Sandhoff slowly decline, losing their ability to walk, eat on their own and communicate. Children are prone to respiratory infections and often experience recurrent bouts of pneumonia.  Many have seizures.

Range of Severity - Juvenile Sandhoff has a broad range of severity. In most cases, the earlier the first signs are observed, the more quickly the disease will progress. For example, a child with first symptoms at age 2 will decline faster than a child with first symptoms at age 5.

Diagnosis

Children affected by the Juvenile form of Sandhoff disease do not exhibit the tell-tale cherry-red spot in the eye.  This can make the road to diagnosis long and challenging. Unfortunately many healthcare providers are not aware of the rare juvenile forms of these diseases and dismiss the initial diagnosis due to the age of the child. 

Management

There is no treatment or cure for Sandhoff disease but there are ways to manage symptoms. These range from life extending interventions like a feeding tube to comfort measures like massage to promote relaxation.

Progressive loss of ambulatory skills followed by respiratory health and seizure management are the main symptom management issues in Juvenile Sandhoff. 

Recommendations for managing the symptoms appear in Find Support.

Newly diagnosed families should read Finding Your Philosophy of Care, available through NTSAD. It will help parents develop a care plan and care goals to aid in major care choices.

Symptoms

First signs - Early symptoms of Late Onset Sandhoff can include clumsiness and muscle weakness in the legs. Once diagnosed, adults often reflect back to their childhood and may notice experiencing symptoms much earlier such as not being athletic and/or speech difficulties or a stutter as a child or teenager.

The mental health symptoms may present first which can lead to an especially long road to diagnosis. About 40% of affected adults experience mental health symptoms such as bi-polar or psychotic episodes.

Gradual Loss of skills - Over time adults with Late Onset Sandhoff slowly decline. Adults frequently require more mobility assistance, i.e. cane to walker to wheelchair. Many experience speech and swallowing difficulties but few require a feeding tube.

Long Road to Diagnosis

Late Onset Sandhoff may be hard to diagnose. Some adults go 5 or more years before learning their true diagnosis. The disease may sometimes be misdiagnosed as Multiple Sclerosis or ALS.

Living with Late Onset Sandhoff

Late Onset Sandhoff is a challenging and debilitating disorder but doesn't always shorten life span like the childhood forms of Sandhoff. Visit Tay-Sachs, Sandhoff and GM-1 Late Onset Support to learn more about living a full and empowered life with Late Onset Sandhoff.

Sandhoff disease is caused by the absence or significantly reduced level of two vital enzymes: Hexosaminidase A (HexA) Hexosaminidase B (HexB). Without HexA & HexB, a fatty substance or lipid called GM2 ganglioside accumulates abnormally in cells, especially in the nerve cells of the brain. This ongoing accumulation, also called "substrate", causes progressive damage to the cells.

The Juvenile and Late Onset forms of Sandhoff occur when the mutations allow the Hex A and Hex B enzymes to function a little bit. Just a small increase in HexA and HexB activity is enough to delay the onset and slow the progression of symptoms.

Inheritance

Sandhoff is an autosomal recessive genetic disorder. Both parents must be a carrier for children to be at risk. There is a 25% chance with each pregnancy the child will be affected.

Sandhoff "breeds true" in a family. If one child is diagnosed with infantile Sandhoff the other children are only at risk for the infantile form. One set of parents could not have children with both the infantile and juvenile forms of the disease.

Gene Location

The gene that causes Sandhoff is located on chromosome 5, specifically 5q13.

alt Read more About Inheritance

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