Methods and gene therapy constructs for treating GM2 gangliosidoses

1. A composition, comprising:

an AAV9 vector; and

a nucleotide sequence encoding from a 5′ end to a 3′ end a first ITR, a CAG promoter, a human HEXB gene, a human HEXA gene, and a self-cleaving P2A linker of 57 nucleotides that links the HEXB gene and the HEXA gene, and a second ITR;

wherein the nucleotide sequence from the beginning of the first ITR through the end of the second ITR consists of nucleotides 1 to 4792 of SEQ ID NO: 1.

2. The composition of claim 1 , further comprising a pharmaceutically acceptable carrier.