R.C. Sproul Jr.: "there is no Shannon to comfort me in the loss of Shannon"

Does anyone know the background of “Denise” and “Shannon”? I looked on his website but only found references to each dying; no mention of why.

Denise was RC Sproul Jr’s Wife, who died Dec 2011 after cancer. Shannon was a special needs daughter that died more recently

Thanks!

http://www.ligonier.org/blog/shannon-macfarlane-sproul/

http://www.legacy.com/obituaries/orlandosentinel/obituary.aspx?pid=1551…

http://www.ligonier.org/blog/denise-sproul-memorial-message/