Sandhoff disease

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Sandhoff disease is a rare inherited disorder that progressively destroys nerve cells (neurons) in the brain and spinal cord (central nervous system). This condition is classified into three major types based on the age at which signs and symptoms first appear: infantile, juvenile, and adult.

The infantile form of Sandhoff disease is the most common and severe form and becomes apparent in infancy. Infants with this disorder typically appear normal until the age of 3 to 6 months, when their development slows and muscles used for movement weaken. Affected infants lose motor skills such as turning over, sitting, and crawling. They also develop an exaggerated startle reaction to loud noises. As the disease progresses, children with Sandhoff disease experience seizures, vision and hearing loss, and intellectual disability. An eye abnormality called a cherry-red spot, which can be identified with an eye examination, is characteristic of this disorder. Some affected children also have distinctive facial features, enlarged organs (organomegaly), or bone abnormalities. Children with the infantile form of Sandhoff disease usually live only into early childhood.

The juvenile and adult forms of Sandhoff disease are very rare. Signs and symptoms are usually milder than those seen with the infantile form, although they vary widely. The juvenile form can begin between ages 2 and 10. Characteristic features include speech difficulties, loss of cognitive function (dementia), seizures, and loss of muscle coordination (ataxia). Adult Sandhoff disease is characterized by problems with movement and psychiatric problems.

ORPHANET DEFINITION A rare autosomal recessive lysosomal disease characterized by accumulation of GM2 gangliosides in the nervous system due to hexosaminidase A and hexosaminidase B deficiency as a consequence of biallelic pathogenic variants in the HEXB gene.

Inheritance

From: MedlinePlus Genetics, National Library of Medicine

Autosomal recessive

Frequency in the source

From: MedlinePlus Genetics, National Library of Medicine

Prevalence at birth: 1-9 / 100 000; Portugal; Value and class. Prevalence at birth: 1-9 / 1 000 000; Netherlands; Value and class. Prevalence at birth: 1-9 / 1 000 000; Czech Republic; Value and class. Prevalence at birth: 1-9 / 1 000 000; Australia; Value and class.

Reported clinical features and what the terms mean

The following findings are associated with this condition in Orphanet. They are not a checklist for diagnosing yourself, and they do not all occur in every affected person. Some are examination, imaging or laboratory findings that cannot be recognised at home.

The frequency labels describe how often a finding was reported among people with the condition in the source. They do not give the chance that a person with that symptom has the condition. Definitions below reproduce HPO terminology; they explain the term, not the likely severity in an individual.

Abnormal glycosphingolipid metabolism · Very frequent (99-80%)

An abnormality of glycosphingolipid metabolism.

Abnormality of movement · Very frequent (99-80%)

An abnormality of movement with a neurological basis characterized by changes in coordination and speed of voluntary movements.

Ataxia · Very frequent (99-80%)

Ataxia refers to impaired coordination of voluntary muscle movement. Cerebellar ataxia refers to ataxia due to dysfunction of the cerebellum. This causes a variety of elementary neurological deficits including asynergy (lack of coordination between muscles, limbs and joints), dysmetria (lack of ability to judge distances that can lead to under- or overshoot in grasping movements), and dysdiadochokinesia (inability to perform rapid movements requiring antagonizing muscle groups to be switched on and off repeatedly).

Blindness · Very frequent (99-80%)

Blindness is the condition of lacking visual perception defined as a profound reduction in visual perception. On the 6m visual acuity scale, blindness is defined as less than 3/60. On the 20ft visual acuity scale, blindness is defined as less than 20/400. On the decimal visual acuity scale, blindness is defined as less than 0.05. Blindness is typically characterized by a visual field of no greater than 10 degrees in radius around central fixation.

Cherry red spot of the macula · Very frequent (99-80%)

Pallor of the perifoveal macula of the retina with appearance of a small circular reddish choroid shape as seen through the fovea centralis due to relative transparency of the macula.

Failure to thrive · Very frequent (99-80%)

Failure to thrive (FTT) refers to a child whose physical growth is substantially below the norm.

Hearing impairment · Very frequent (99-80%)

A decreased magnitude of the sensory perception of sound.

Kyphosis · Very frequent (99-80%)

Exaggerated anterior convexity of the thoracic vertebral column.

Macrocephaly · Very frequent (99-80%)

Occipitofrontal (head) circumference greater than 97th centile compared to appropriate, age matched, sex-matched normal standards. Alternatively, a apparently increased size of the cranium.

Motor deterioration · Very frequent (99-80%)

Loss of previously present motor (i.e., movement) abilities.

Seizure · Very frequent (99-80%)

A seizure is an intermittent abnormality of nervous system physiology characterized by a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain.

Progressive psychomotor deterioration · Very frequent (99-80%)

Full cheeks · Frequent (79-30%)

Increased prominence or roundness of soft tissues between zygomata and mandible.

Hepatomegaly · Frequent (79-30%)

Abnormally increased size of the liver.

Other findings in the same source

From: Orphanet

Additional reported features include Muscle weakness (Frequent (79-30%)); Recurrent respiratory infections (Frequent (79-30%)); Splenomegaly (Frequent (79-30%)); Congestive heart failure (Occasional (29-5%)); Skeletal dysplasia (Occasional (29-5%)). This is a selected summary, not a complete description of the condition.

When it may begin

From: MedlinePlus Genetics, National Library of Medicine

Adolescent; Adult; Childhood; Infancy

Inheritance in the source

From: MedlinePlus Genetics, National Library of Medicine

Autosomal recessive

Frequency and the population described

From: MedlinePlus Genetics, National Library of Medicine

Prevalence at birth: 1-9 / 100 000; Portugal; Value and class. Prevalence at birth: 1-9 / 1 000 000; Netherlands; Value and class. Prevalence at birth: 1-9 / 1 000 000; Czech Republic; Value and class. Prevalence at birth: 1-9 / 1 000 000; Australia; Value and class.

Understanding the inheritance label

From: MedlinePlus Genetics

An autosomal recessive pattern usually involves disease-causing changes in both copies of a gene. Parents may each carry one altered copy without having the condition themselves. A genetic counsellor can explain carrier testing and reproductive implications using the actual laboratory findings, rather than the condition name alone.

Which doctor should you see?

The suggested department for discussing Sandhoff disease is Metabolic Medicine, with a metabolic specialist / clinical geneticist as the relevant type of clinician. Paediatrician (children) or physician (adults), with metabolic specialist / clinical geneticist referral.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Is a biochemical or molecular result needed to clarify the diagnosis?
• Does this condition require an individual plan for illness or reduced food intake?
• Should nutrition advice come from a specialist metabolic dietitian?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Sandhoff disease. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.