I am sorry to read what was said to your son and I am sure that it would be very hurtful to hear. However, I do believe that the teacher was trying to make a valid point on how some schools of Buddhism think about cause and effect leading to illness. The issue here of course is that we all know that AS is NOT an illness. But hey your son's teavher is probably amongst the great unenlightened.

See the following extract below taken from : http://www.dharma-haven.org/tibetan/tibe...ealing.htm in particualr the third paragrapgh which contains:" Tibetan Buddhist believes that karma (simply stated, the law of cause and effect) from one's previous incarnations can also be responsible for our illnesses in our present experience".

I hope this helps at least explain why it may have happened - but I know as an Aspie and a prent of an aspie that this will not take the pain away.

ETIOLOGY OF ILLNESS

In an early Mahayana text, the Buddhist sage Vimalakirti mused that, "All sentient beings are ill" (Birnbaum, p.13). To the Tibetan, the inevitability of suffering and illness is a reflection of the fact that we are born. The Tibetans believe that we "take birth" because we are ignorant of the true nature of reality and that it is this ignorance that is the cause of all suffering and disorder. Dr. Yeshi Donden remarked that "the root [of illness] is beginningless ignorance" and that "ignorance is with us like our own shadow . . . even if we think that we are in very good health, actually we have had the basic cause of illness since beginningless time" (Donden, p. 26).  

Tibetans believe that our false perceptions of the world and its projections actually change the world, which is fundamentally neutral. Moreover, people become attached to ego-centered views, which "contain the seeds of profound misunderstanding of what it means to have Being in this world" (Walsh-Frank, p. 8). Consequently, because "all phenomena are mere reflections and designation of the mind" (Thonduk, p.193), and the mind is driven by delusional thinking, samsara (our perception of the phenomenal world) is filled with suffering.  

Furthermore, the Tibetan Buddhist believes that karma (simply stated, the law of cause and effect) from one's previous incarnations can also be responsible for our illnesses in our present experience. Sakyamuni, the historical Buddha, explained this principle when he said:  

In sooth to every man that's born  
A hatchet grows within his mouth,  

Wherewith the fool, whene'er he speaks  

And speaks amiss, doth cut himself . . . (quoted from Samyutta-nikaya in Birnbaum, p.9)

Thus, the distant causes of the diseases are seated in the past mental environment which was influenced by "afflictive emotions"--mental factors that are the root cause of all illness. While these factors are impossible to enumerate, they are all the consequences of ignorance (Donden, p.15). Ignorance generates other negative states of mind such as desire, hatred, jealousy and pride. Such negative emotions drive our mentations, and our mentations contribute to our suffering.  However, our emotional energies are neither good nor bad in themselves; for example, the energy/intelligence that turns to hatred when siezed in the neurotic grip of ego can also manifest as simple, clear awareness of the true situation--thus it is how we relate to our emotional energies that is crucial to well-ness. Understanding one's emotions is an essential part of the Buddhist journey to full awakening and freedom form unwanted conditions of all sorts. However, since most of us have very little ability to work with our emotional energies without creating negative experiences, medicines and other remedies are required.  

While Tibetan notions of the law of karma imply infinite interlinked causes for any single event, three emotions, known as the "Three Interior Poisons," are considered to be at the root of all illness. The first poison is desire or passion, which implies grasping at objects or pleasant experiences. Desire is also perceived as "grasping at self" where self is our involvement with any object of our desire whether it is a chair, person or idea (Tsarong, p.17). And self, which involves a subject grasping an object, is an illusion to which we cling, because we still do not understand that anitya(impermanence) is a primordial condition of living in samsara. Similarly, hatred, or aversion, regarded as the second poison, consists of pushing away unpleasant experiences or objects. Finally, ignorance, or confusion, which involves misunderstanding the nature of an object or a particular experience, is the third poison of the mind.