rare-earth elements
rare-earth ions
rare-earth metals
rare autosomal recessive disorder
rare benign neoplasm
rare benign tumor
rare benign tumour
rare bleeding disorders
rare case
rare case report
rare cause
rare clinical entity
rare clinical presentation
rare combination

rare complication
rare complications
rare condition
rare congenital anomaly
rare disease
rare disorder
rare disorders
rare earth
rare earth complexes
rare earth elements
rare earth ions
rare entity
rare event
rare example
rare exceptions

rare finding
rare form
rare genetic disorder
rare genetic syndromes
rare haplotypes
rare hereditary disorder
rare instances
rare lesion
rare malformation
rare malignancy
rare manifestation
rare mutations
rare neoplasm
rare occasions
rare occurrence

rare ones
rare opportunity
rare outcome
rare phenomenon
rare phenotype
rare plant species
rare plants
rare polymorphism
rare population
rare presentation
rare reports
rare side effects
rare site
rare species
rare subtype

rare syndrome
rare taxa
rare tumor
rare tumour
rare type
rare variant
rare variants
rare variation
rarefaction curves