This is what the DSM IV says:
(I) Qualitative impairment in social interaction, as manifested by at least two of the following:
(A) Marked impairments in the use of multiple nonverbal behaviors such as eye-to-eye gaze, facial expression, body posture, and gestures to regulate social interaction
(B) Failure to develop peer relationships appropriate to developmental level
(C) A lack of spontaneous seeking to share enjoyment, interest or achievements with other people, (e.g.. by a lack of showing, bringing, or pointing out objects of interest to other people)
(D) Lack of social or emotional reciprocity.
By no means does this mean there is no ability to empathize; it means there may be a lack of it in some cases.
Empathy is organic, and one of the things that makes social animals successful. Some people have an impaired sense of empathy, and it's development can be systematically altered by the environment, such as the case with sociopaths. "Social reciprocity" would seem to suggest something more incidental, such as manners and being curtious; I cant say if this is meant to be interchangeable with empathy in this context, but the two are not mutually inclusive.
In my case, I do not always experience it at appropriate times. So, yes there is a definite lack of it, but it's not absent from a human perspective.