A) Brain MRIs showing that ADD1 variants are associated with agenesis of corpus callosum. Case I-1 carrying the homozygous ADD1 variant Chr4:2877811 A>T (hg19, p.Arg57Trp ) exhibits agenesis of corpus callosum (ACC), a grossly enlarged 3rd ventricle, and hypoplasia of white matter and cerebellar vermis. Case II-1 carrying the de novo truncation variant Chr4:2906748_G>A (p. Trp473*, NM_014189) exhibits partial agenesis of the corpus callosum, with only a segment of the anterior body present; there is also abnormal lobulation and disorganized subluxation and folia of the inferior and lateral aspects of the left cerebellar hemisphere. Case III-1 carrying the de novo truncation variant Chr4:2930065-2930075 delGCCAGCCCCGA, NM_001119, p.Glu680Argfs*7) exhibits complete agenesis of the corpus callosum and enlarged ventricles.
B) ADD1 exon-intron structure and the positions of variants reported in this study.
See also Figure S1.