To the Editor.—
Xeroderma pigmentosum is an autosomal recessive disease characterized by marked sunlight sensitivity and early development of actinic degeneration and malignancies, primarily basal and squamous cell types.Although the specific cellular defect is as yet unknown, recent studies seem to indicate an enzymatic deficiency. Cleaver had demonstrated that xeroderma pigmentosum fibroblasts when grown in tissue culture show diminished ability to repair short-wave ultraviolet DNA damage.1 Epstein reported that xeroderma pigmentosum epidermal cells showed defective DNA repair in vivo.2In vitro tritiated thymidine radiographs were prepared utilizing epidermal tissue cultures obtained from two female siblings ages 4 and 6 years, their parents, two normal controls, and a patient with basal cell nevus syndrome.Counts were made at 14 days exposure in the initial study and at 60 days in the second study. Only epidermal cells showing sparse nuclear graininess were considered to represent thymidine uptake for purposes of unscheduled synthesis. Densely labeled cells in premitosis were not counted.
Currie JM, Nordquist RE. XERODERMA PIGMENTOSUM. Arch Dermatol. 1970;102(2):236. doi:10.1001/archderm.1970.04000080108030