Research available about cryptochordism in Shih Tsu.?

I have a 5.5 month old male Shih Tsu who has cryptochordism (undescended testicles). He will be neutered to protect his health, of course. This issue was brought to the attention of the owners of the sire and the dam; to which they BOTH responded that they had never heard of such a thing and are even considering breeding the two together again. I have been unable, after 4.5 hours of Internet searching, to find any printable or down loadable and email able research about this condition and the likelihood of it being hereditary. Does anyone have a clue where I can get this information and be able to send it on to the owners of the sire and dam?