Interestingly, it is only individuals that are heterozygous for TREM2 that are at risk for AD: homozygous, autosomal recessive mutations for TREM2 result in The Nasu-Hakola disease in some individuals characterized by bone cysts and dementia [75], while resulting in fronttemporal dementia without bone disease in others [76]. This evidence concerns the gene TREM2 and bone disorder.