Tay-Sachs disease

• 330.1 Cerebral lipidoses

• E75.02 Tay-Sachs disease

• 5B: Impaired Neuromotor Development

Description

• Progressive autosomal recessive genetic disorder
• Infant lacks protein, beta-hexosaminidase A that prevents the accumulation of the lipid, ganglioside GM-2, thus causing damage to brain cells.

Essentials of Diagnosis

• Genetic defect of chromosome 15

General Considerations

• Categories:
  • Infantile: most common
    • Symptoms appear between 3 to 6 months of age.
  • Juvenile: Symptoms begin between 2 to 5 years old.
  • Adult: Symptoms begin during adolescence or as young adult.

Demographics

• Carrier rates
  • Ashkenazi Jewish: 1/272
  • Total population: 1/2503
  • French Canadian, Louisiana Cajun, and Ashkenazi Jewish: 1/273
  • British Isles or Irish: range between 1/50 to 1/1503
  • Equally affects males and females

Signs and Symptoms

• Deafness
• Blindness
• Loss of gag reflex
• Difficulty swallowing
• Muscle weakness
• Hypotonia
• Dementia
• Irritability
• Seizures
• Paralysis
• Regression in gross motor and fine motor skills
• Cherry-red spot on eyes

Possible Contributing Causes

• Progressive autosomal recessive genetic disorder
• Both parents must carry the defective Tay-Sachs gene, the child has a 25% chance of developing the disease

Differential Diagnosis

• Gaucher disease
• Niemann-Pick disease
• Danshoff disease
• Hepatosplenomegaly

Functional Implications

• Progressive muscle weakness resulting in decline in gross and fine motor skills such as inability to sit, ambulate or feed self

Laboratory Tests

• Blood test for hexosaminidase levels

Diagnostic Procedures

• DNA analysis

• Geneticist
• Neurologist
• Ophthalmologist
• Speech pathologist

• Inability to roll
• Inability to commando crawl or creep on hands and knees
• Inability to sit
• Inability to ambulate

• Early intervention developmental profile
• Neonatal behavioral assessment scale
• Pediatric evaluation of disability inventory
• Manual muscle test

• Developmental activities to:
  • Prevent loss of motor milestones
  • Prevent loss of muscle strength
• Therapeutic exercise to:
  • Prevent muscle contractures
  • Strengthen
  • Stretch
• Functional activities
  • Transfers
  • Gait training
  • Stair climbing

• Sit supported in adaptive chair for 15 minutes during play activities in 1 month.
• Prevent loss of range of motion to allow for optimal positioning within 3 months.
• Take steps in a gait trainer to allow for independent mobility and upright function within 4 months.
• Transfer from wheelchair to/from classroom chair with moderate assistance in 6 months.

• Infantile form: Child life expectancy is between 4 or 5 years old.1