Author 3 (JS) conceived of the study and contributed to experimental design, developed the computer analysis software, and had primary responsibility for manuscript drafting.

Author 6 EPK conceived the study and participated it its design and assisted in writing the manuscript.

Author 5 (VVVSM) has conceived and coordinated the study.

Author 2 (Y.T.) conceived of the study, participated in its design and coordination and carried out the catenation assay.

Author 4 XWD conceived the study, raised the funding for the project, and participated in its design and coordination.

Author 10 (VVM) has conceived and coordinated the study.

Author 3 (AE) conceived the study and participated in its design, coordination and reporting.

Author 3 conceived of the study and participated in its design and execution.

Author 5 (JH) conceived of the family data collection and supervised AR.

Author 5(CVM) conceived of the study, participated in the design and coordination of the studies, and helped draft the manuscript.