In alternative embodiments, the invention provides nucleic acid sequences that are genetic polymorphic variations of the human TMEM216 gene, and TMEM216 polypeptide encoded by these variant alleles. In alternative embodiments, the invention provides methods of determining or predicting a predisposition to, or the presence of, a ciliopathy (or any genetic disorder of a cellular cilia or cilia anchoring structure, basal body or ciliary function) in an individual, such as a Joubert Syndrome (JS), a Joubert Syndrome Related Disorder (JSRD) or a Meckel Syndrome (MKS). In alternative embodiments, the invention provides compositions and methods for the identification of genetic polymorphic variations in the human TMEM216 gene, and methods of using the identified genetic polymorphisms and the proteins they encode, e.g., to screen for compounds that can modulate the human TMEM216 gene product, and possibly treat JS, JSRD or MKS. In alternative embodiments, the invention provides cells, cell lines and/or non-human transgenic animals that can be used as screening or model systems for studying ciliopathies and testing various therapeutic approaches in treating ciliopathies, e.g., JS, JSRD or MKS.