Almost all studies into ASD published in English has been by carried out by culturally British or American people using culturally British or American people as their subjects. Far less research appears to have been carried out into people from culturally foreign backgrounds, or people who follow religions other than Christianity (and possibly Judaism in the US).
Therefore information about how ASD manifests in such people is scarce and largely unknown within psychology and ASD support communities. American publications are very unlikely to include findings from foreign communities which are significant in Britain but smaller, or even invisible, in the US.
My own experience of the NAS is that it is dominated by white, British, socially conservative, middle class people from the suburbs and the shires. The NAS superficially claims to uphold an inclusive and multicultural society but in reality it has a generally poor knowledge of foreign cultures and non-Christian religions.