Bloom syndrome (MONDO_0008876) (BSyn) is a rare chromosomal breakage syndrome characterized by a marked genetic instability associated with pre- and postnatal growth retardation, facial sun-sensitive telangiectatic erythema, increased susceptibility to infections, and predisposition to cancer. Also known as: BSyn, Bloom-Torre-Machacek syndrome, congenital telangiectatic erythema syndrome.