Welcome to the Rare Classroom, a new series from Patient Worthy. Rare Classroom is designed for the curious reader who wants to get informed on some of the rarest, most mysterious diseases and conditions. There are thousands of rare diseases out there, but only a very small number of them have viable treatments and regularly make the news. This series is an opportunity to learn the basics about some of the diseases that almost no one hears much about or that we otherwise haven’t been able to report on very often.

Eyes front and ears open. Class is now in session.

The disease that we will be learning about today is:

Sandhoff Disease

Also called Sandhoff-Jatzkewitz disease.

What is Sandhoff Disease?

• Sandhoff disease is a genetic lipid storage disorder resulting in a deficiency in the ability to produce beta-hexosaminidases A and B​. 
  • These enzymes are responsible for the processing of several components of the neuronal membranes, such as certain oligosaccharides, ganglioside GM2, and others
  • With the processing ability gone, these metabolites accumulate in the body and lead to progressive damage and destruction of the nervous system
• In terms of symptoms, Sandhoff disease is nearly indistinguishable from Tay-Sachs disease, which similarly impacts the same enzymes
• Sandhoff disease is divided into three distinct forms:
  • The ‘classic’ or infantile form, which is the most common and is universally lethal
  • The juvenile form, in which symptoms begin between age three and ten; patients typically die in their teens
  • The adult-onset form, which has delayed symptom onset and is less severe; usually not lethal

How Do You Get It?

• This is a recessive genetic disorder in which both parents must carry the mutated gene in order to pass along the disease
• Mutation of the HEX B gene has been identified as the cause of Sandhoff disease
• Some research has suggested that people of certain ethnic backgrounds may be at higher risk, including:
  • Christian Maronite communities of Cyprus
  • The Métis indigenous people of Saskatchewan
  • The Creole population of northern Argentina

What Are the Symptoms?

• Symptom onset depends on the form of Sandhoff disease, but in the classic form, symptoms begin at around six months of age and include:
  • Regression of developmental milestones
  • Muscle degeneration
  • Sudden reactions to loud noises
  • Motor weakness
  • Hearing loss
  • Vision loss
  • Infections
  • Breathing problems
  • Enlarged liver and spleen
  • Cognitive impairment
  • Seizures
• Symptoms in the juvenile and adult form are less severe, with the adult form sometimes leading to only to muscle weakness

How Is It Treated?

• There is no standard treatment or cure for Sandhoff disease
• Symptomatic treatment includes clearing of the airways, management of infections, and proper nutrition and hydration
• Frequent surveillance is critical to support respiration
• Anticonvulsants may be used to relieve seizures
• In the future, Sandhoff disease could be a viable candidate for gene therapy development

Where Can I Learn More???

• Check out our cornerstone on this disease here.
• Learn more about this disease from the National Tay-Sachs Disease & Allied Diseases Association.