Borjeson-Forssman-Lehmann syndrome (BFLS) is an extremely rare disorder characterized by mental retardation, obesity, seizures, failure of the testes in males or the ovaries in females to produce hormones (hypogonadism), and distinctive facial features. Affected infants often experience delays in reaching developmental milestones. The exact symptoms vary from case to case, even among members of the same family.
BFLS is caused by disruptions or changes (mutations) of the PHF6 gene on the X chromosome. This mutation is usually transmitted as an X-linked recessive trait, which means the disorder is fully expressed predominantly in males. Females who carry a single copy of the disease gene (heterozygous carriers) may develop some variable features of the disorder, however, in some instances they can have features similar to the affected males (i.e. be considered as affected with the syndrome).