When development stops. Test for Tay-Sachs.
When an infant or child suddenly stops being able to do the things that come naturally, the distress caused by the ‘wait and see’ approach can put enormous burden on family dynamics and potentially rob them of precious time.
Performing a simple blood test at the first signs of any issue, or referring to an opthamologist to check for a macular cherry-red spot,1 could have a life changing effect on a young family and the quality time they have left.
Early diagnosis and referral to the CATS Foundation offers families the opportunity to be part of research into a viable treatment, to join a community and gain support when facing this devastating disease.
Blood tests for Tay-Sachs and Sandhoff disease
The first blood sample, which will confirm a diagnosis, looks at the activity of the enzyme hexosaminidase A. This is taken as a standard blood test, with the sample usually drawn into a lithium heparin tube.*
If hexosaminidase A activity is found to be reduced or absent, further genetic testing can be performed to determine if there is a mutation in the HEXA or HEXB genes.
Blood Test
At the first sign of a developmental stop, refer the family to a paediatric consultant to perform a straight-forward blood test.1
Macular Cherry-Red Spot Test
Alternatively, refer them to an ophthalmologist to test for a macular cherry-red spot.1
Testing for a cherry-red spot
Examination via ophthalmoscopy or slit lamp will reveal a cherry-red spot in the centre of the macula. For Tay-Sachs and Sandhoff disease this is due to deposition of unmetabolised substances in the neuronal cell bodies surrounding the macula. There can be a wide differential diagnosis of conditions causing a cherry-red spot, including lysosomal storage disorders, retinal ischaemia and retinal infarction.
*Confirm correct bottle and sample conditions with local laboratory prior to performing the test.
Roles of healthcare professionals in diagnosis
General Practitioner
The GP will often be the first port of call for worried parents who notice changes in their child. After history and examination give concern for a neurodevelopmental condition, specialist referral to a paediatrician is advised. After a diagnosis is made, the GP will play an integral part in the management and support, both of the child and the family.
Paediatrician
Likely to both be responsible for making the diagnosis via history, examination and blood testing, but also counselling worried parents about what this means for the future development and needs of their child. Onward referral for specialist care may be needed. They will need to liaise with primary care to ensure management of the child in the community is optimal.
Ophthalmologist
May have received a referral either from the GP or paediatrician to perform an examination of the retina as part of a diagnostic workup. The presence of a cherry-red spot in the macula increases the likelihood of the symptoms being due to Tay-Sachs, Sandhoff disease or another lysosomal storage disorder.
About Tay-Sachs
Tay-Sachs is a genetic disorder caused by a defect in the HEXA gene which produces the beta-hexosaminidase A enzyme.2 The enzyme is important as it breaks down harmful waste products in the brain and without it these build up and cause extensive damage to the brain’s nerve cells.2,3 Physically, an individual diagnosed with Tay-Sachs will suffer a relentless deterioration of mental and physical abilities.2,3
About Sandhoff
Sandhoff disease is very similar to Tay-Sachs but the defected gene, called HEXB, does not allow the production of two enzymes (beta-hexosaminidase A and beta-hexosaminidase B).2 The disease also results in premature death in a sufferer and the signs and symptoms are the same as in Tay-Sachs.2
The CATS Foundation
Dedicated to finding a cure, the CATS foundation vows not to stop work until there is a viable treatment for Tay-Sachs or Sandhoff disease.
Their objectives are to support, research, and raise awareness, so that no family affected by the diseases feel isolated after a diagnosis.
Useful Resources:
Learn more about The CATS Foundation.
PUB MED on the Denver Scale, a guide for screening developmental progress in young children.
1. Toro C, Shirvan L, Tifft C. HEXA Disorders. In: Adam MP, et al, eds. GeneReviews. University of Washington, Seattle; 1993-2023. Accessed Nov 2023. Available at https://www.ncbi.nlm.nih.gov/books/NBK1218.
2. Toro C, et al. Neurosci Lett. 2021;764:136195.
3. Eswari G, et al. Sch Acad J Pharm. 2021;10(7): 111-114.