Been reading up on Mattsson and from what I can tell from google translate, his Mom had breast cancer in 1997, survived then the cancer returned in 2008 and metastasized and was uncurable. His mother passed away in 2012.
His youngest brother has a "cerebal injury" and needs special care.
His mother and family wrote a blog about dealing with the cancer (in Swedish):
http://joelisacadam.blogspot.ca/