Any autosomal recessive malignant osteopetrosis in which the cause of the disease is a mutation in the PLEKHM1 gene. The disease is autosomal recessive osteopetrosis 6 (MONDO_0012679). Also known as: OPTB6, PLEKHM1 osteopetrosis (disease), autosomal recessive intermediate osteopetrosis, autosomal recessive osteopetrosis intermediate form, autosomal recessive osteopetrosis type 6, osteopetrosis (disease) caused by mutation in PLEKHM1, osteopetrosis, autosomal recessive type 6.