Yes, there are instances in which one can with right speak of “discrimination on the ground of sexual orientation”. For example, Russia has this week enacted a law that (according to media reports) bans people with sexual disorders (among which it quotes, in particular “transsexuals, fetishists, and pedophiles”) from obtaining a driving license. Also affected by the ban are cleptomaniacs and gamblers.
The measure does not seem to have any comprehensible purpose. While everybody can understand why a legislator might decide that persons with sexual disorders should not be allowed to marry, or to adopt and raise children, it is less clear how such sexual disorders might undermine their ability to drive cars.