Here I present: “AB-variant GM2-Gangliosidosis”, Victor McKusick, Mendelian Inheritance in Man’, 1966. AB-變異GM2-神經節苷症。 icd10=E75.00
INTRODUCTION.
AB variant GM2-gangliosidosis is an autosomal recessive metabolic disorder that causes progressive destruction of nerve cells in the brain and spinal cord. It has a similar pathology to Sandhoff disease and Tay–Sachs disease. The three diseases are classified together as the GM2 gangliosidoses, because each disease represents a distinct molecular point of failure in the activation of the same enzyme, beta-hexosaminidase. AB variant is caused by a failure in the gene that makes an enzyme cofactor for beta-hexosaminidase, called the GM2 activator
(GM2A).
The GM2-gangliosidoses are a group of disorders caused by excessive accumulation of ganglioside GM2 and related glycolipids in the lysosomes, mainly of neuronal cells.
There is evidence GM2-gangliosidosis AB variant is caused by homozygous mutation in the GM2A gene on cytogenetic location 5q33.1 and genomic coordinates 5:151,253,185-151,270,440 . The screenshot of the GM2A gene 17,256 bp (base pairs) of DNA sequence length is shown BELOW. Nine (9) other genes besides GM2A in the 5q33.1 cytogenetic location are listed BENEATH.
| Coordinate | Symbol | Genomic Name |
| 5:151,020,591 | GPX3 | Glutathione peroxidase-3, plasma |
| 5:151,029,943 | TNIP1 | TNFAIP3-interacting protein 1 |
| 5:151,100,706 | ANXA6 | Annexin A6 (calcium-binding protein p68) |
| 5:151,181,052 | CCDC69 | Coiled-coil domain-containing protein 69 |
| 5:151,253,185 | GM2A | GM2 ganglioside activator protein |
| 5:151,276,358 | SLC36A3 | Solute carrier family 36 member 3 |
| 5:151,314,972 | SLC36A2 | Solute carrier family 36 member 2 |
| 5:151,344,596 | SLC36A1 | Solute carrier family 36 member 1 |
| 5:151,504,092 | FAT2 | FAT atypical cadherin 2 |
| 5:151,661,096 | SPARC | Osteonectin (secreted protein, acidic-rich cysteine) |
