Regex for matching specific numbers separated by comma

I have a regex which matches any combination of the number 1,7 and 99, separated by commas. E.g. these should be matched:

1
1,7
1,99
99,1,7

While these should not match:

1,
8
8,99
,7
1,7,99,

The following works fine, but can probably be shortened and made more efficient?

/^(1|7|99)(,?(1|7|99)(,?(1|7|99))?)?$/