# data[].attributes.body
The most common mutation of Tay-Sachs disease is a on Exon 5. A deletion occurs in cell line 904 that causes a frameshift mutation (9). Due to the frameshift mutation, there is a disruption of the whole gene since it does not occur in a group of three but rather the rest of the gene after the mutation (9). Other types of mutations on the HEXA gene lead to Tay-Sachs disease, such as the known "Tay-Sachs insertion", however, the insertion on Exon 5 is the most common. Some of these other mutations lead to abnormal splicing, incorrect amino acids being produced, and stop codons being produced.

# data[].attributes.body
Wild Type DNA Sequence

5'-TCAACAAGAC[TG]AGATTG-3'
[deletion occurs here]

Mutated DNA Sequence with deletion

5'-TCAACAAGACAGATTG-3'

Wild Type mRNA sequence

5'-CAAUCU[CA]GUCUUGUUGA-3'

mRNA sequence with deletion

5'-CAAUCUGUCUUGUUGA-3'

Wild Type amino acid sequence

ASN,LEU,SER,LEU,VAL

Amino acid sequence with deletion:

ASN,LEU,SER,CYS,STOP

As stated previously, this is the deletion on Exon 5. The frameshift mutation that occurs due to the deletion would cause a stop codon to be produced. This changes the overall length and structure of the protein, making it much shorter. With this new amino acid sequence, the production of the enzyme that is normally produced, HEXA, would stop (2).

# data[].attributes.body
Due to the deletion in Tay-Sachs Disease, the production of the enzyme beta-hexosaminidase A (Hex-A) is halted. This Hex-A enzyme prevents the abnormal build up of GM2 ganglioside lipid (3). As a result of Hex-A not breaking down the GM2 ganglioside lipid, it builds up to a toxic level, particularly in neurons in the central nervous system (4). Damage caused by the buildup of GM2 ganglioside leads to the dysfunction and eventual death of these neurons, which causes the signs and symptoms of Tay-Sachs disease (8).

# data[].attributes.body
In the infantile form of Tay-Sachs Disease some of the most common symptoms are exaggerated startle and response to loud noises, loss of motor skills, muscle weakness, and seizures (5). With the infantile form of Tay-Sachs Disease, most individuals do not live past 6 years old. The symptoms also being occurring at around 3 to 6 months old.

# data[].attributes.body
The HEXA gene encodes a member of the glycosyl hydrolase 20 family of proteins. The encoded preproprotein is proteolytically processed to generate the alpha subunit of the lysosomal enzyme beta-hexosaminidase. This enzyme, together with the cofactor GM2 activator protein, catalyzes the degradation of the ganglioside GM2, and other molecules containing terminal N-acetyl hexosamines (3).

# data[].attributes.body
1. 2 Kids Get First Gene Therapy for Tay-Sachs Disease. 2022 Feb 14. Industrial Equipment News (IEN). https://www.ien.com/product-development/news/22056063/2-kids-get-first-gene-therapy-for-taysachs-disease.

‌
2. Hexa Gene - Hexa Gene Chromosome 15 PNG Image | Transparent PNG Free Download on SeekPNG. SeekPNGcom. [accessed 2022 Oct 28]. https://www.seekpng.com/ipng/u2e6q8i1u2e6a9w7_hexa-gene-hexa-gene-chromosome-15/.

3. HEXA hexosaminidase subunit alpha [Homo sapiens (human)] - Gene - NCBI. 2019. Nihgov. https://www.ncbi.nlm.nih.gov/gene/3073.

4. Irish ancestry focus of Tay-Sachs families. 2013 Jan 27. Daily Local. https://www.dailylocal.com/2013/01/27/irish-ancestry-focus-of-tay-sachs-families-2/.

5. Mayo Clinic. 2018 May 16. Tay-Sachs disease - Symptoms and causes. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/tay-sachs-disease/symptoms-causes/syc-20378190.

6. Wikipedia Contributors. 2017 Oct 27. HEXA. Wikipedia. https://en.wikipedia.org/wiki/HEXA.

7. The Gene - Tay Sachs Disease. sitesgooglecom. https://sites.google.com/site/tsdisease/the-gene.

8. Tay-Sachs disease: MedlinePlus Genetics. medlineplusgov. https://medlineplus.gov/genetics/condition/tay-sachs-disease/#causes.

9. Triggs-Raine B, Akerman B, Clarket J, Gravel R. 1991. Sequence of DNA Flanking the Exons of the HEXA Gene, and Identification of Mutations in Tay-Sachs Disease. Am J Hum Genet. 49:1041–1054. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1683266/pdf/ajhg00082-0138.pdf.

‌

# data[].attributes.attachment_link.description
Hexosaminidase A and the cofactor GM2 activator protein catalyze the degradation of the G M2 gangliosides and other molecules containing terminal N-acetyl hexosamines. Hexosaminidase A is a heterodimer composed of an alpha subunit (this protein) and a beta subunit. The alpha subunit polypeptide is encoded by the HEXA gene while the beta subunit is encoded by the gene.

# data[].attributes.body
Tay-Sachs Disease is caused by a frameshift insertion mutation in the HEXA gene which is located at chromosome 15q23.