Bloom syndrome (BSyn) is characterized by severe pre- and postnatal growth deficiency, immune abnormalities, sensitivity to sunlight, insulin resistance, and a high risk for many cancers that occur at an early age. Despite their very small head circumference, most affected individuals have normal intellectual ability. Women may be fertile but often have early menopause, and men tend to be infertile, with only one confirmed case of paternity. Serious medical complications that are more common than in the general population and that also appear at unusually early ages include cancer of a wide variety of types and anatomic sites, diabetes mellitus as a result of insulin resistance, chronic obstructive pulmonary disease, and hypothyroidism.

Hypotrichosis-lymphedema-telangiectasia-renal defect syndrome is an autosomal dominant disorder characterized by these 4 features, which begin in early childhood and are progressive (summary by Moalem et al., 2015).