Dr. Cotter's article is available as a
PDF file, size 1.6MB. That article was published in 1995 and was apparently based on results obtained in 1992 or earlier, so I'm sure there has been further research since then. The article describes two patients, one 77 and one 81 at the time, and concludes by suggesting that all elderly patients with microcytic sideroblastic anemia should be considered candidates for X-linked sideroblastic anemia (XLSA), especially if they have a good vitamin B6 (pyridoxine) response.
According to a 2003 report from doctors in Sendai, Japan (
PDF, 52K) late-onset XLSA is extremely rare, with only 3 cases reported to date, at that time. So a good response to B6 is great news, while unlikely to be related to XLSA.
Is that your understanding too?