( ( Also ( due ( to ( ( the complexity ) ( of ( the ( immune system ) ) ) ) ) ) ) ( , ( it ( ( ( ( is not ) unlikely ) ( that ( there ( may ( be ( ( rare forms ) ( of ( acquired ( immunodeficiency ( ( for which ) ( we ( ( do not ) ( know ( the cause ) ) ) ) ) ) ) ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (S (ADVP (RB Also)) (ADJP (JJ due) (PP (TO to) (NP (NP (DT the) (NN complexity)) (PP (IN of) (NP (DT the) (JJ immune) (NN system))))))) (, ,) (NP (PRP it)) (VP (VBZ is) (RB not) (ADJP (JJ unlikely)) (SBAR (IN that) (S (NP (EX there)) (VP (MD may) (VP (VB be) (NP (NP (JJ rare) (NNS forms)) (PP (IN of) (NP (VBN acquired) (NN immunodeficiency) (SBAR (WHPP (IN for) (WHNP (WDT which))) (S (NP (PRP we)) (VP (VBP do) (RB not) (VP (VB know) (NP (DT the) (NN cause)))))))))))))) (. .)))
Also due to the complexity of the immune system, it is not unlikely that there may be rare forms of acquired immunodeficiency for which we do not know the cause.
(ROOT (S (NP (DT The) (NN term)) (ADVP (RB immunodeficiency)) (VP (VBZ means) (NP (NP (DT a) (NN failure) (, ,) (NN insufficiency) (, ,) (CC or) (NN delay)) (PP (IN in) (NP (NP (DT the) (NN response)) (PP (IN of) (NP (NP (DT the) (JJ immune) (NN system)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (MD may) (VP (VB be) (VP (VBN acquired) (CC or) (VBN inherited)))))))))))) (. .)))