LAMB3 and Alzheimer disease: We and others showed that heterozygous variants in some of these same genes can causehypoplastic AI without clinical skin abnormalities (McGrath et al. 1996; Murrell et al. 2007; Yuen et al. 2012; Poulter, El-Sayed, et al. 2014).LAMB3 variants have now been reported as a cause of AD AI in 10families (Appendix Table 1).