TYROBP and Nasu-Hakola disease: Biallelic (both alleles carry a variant, homozygous or compound heterozygous) loss-of-function variants in either TYROBP or TREM2 cause Nasu-Hakola disease (NHD) known also as polycystic lipomembranous osteodysplasia with sclerosing leukoencephalopathy (PLOSL).