ISL1 and Muscle weakness: Of the 113 candidate genes that were retained after filtering of variants based on confidence, population frequency, mode of inheritance, and computationally predicted deleteriousness scores, 12 were prioritized based on (1) gene expression in Isl1+ CN6 and CN7 developing rhombomere 4 motor neurons in embryonic mice,5,40 (2) known phenotypes in animal models and humans, and/or (3) relations to known congenital facial weakness disease-causing genes.