Clinical, cellular, and molecular features of an Israeli xeroderma pigmentosum family with a frameshift mutation in the XPC gene: sun protection prolongs life.
An Ashkenazi Jewish Israeli family with two children affected with severe xeroderma pigmentosum was investigated. A son, XP12TA, developed skin cancer at 2 y and died at 10 y. A daughter, XP25TA, now 24 y old, was sun protected and began developing skin cancers at 10 y. Their cultured skin fibroblasts showed reductions in post-ultraviolet survival (11% of normal), unscheduled DNA synthesis (10% of normal), global genome DNA repair (15% of normal), and plasmid host cell reactivation (5% of normal). Transcription-coupled DNA repair was normal, however. Northern blot analysis revealed greatly reduced xeroderma pigmentosum complementation group C mRNA. A plasmid host cell reactivation assay assigned the cells to xeroderma pigmentosum complementation group C. Cells from both parents and an unaffected child exhibited normal post-ultraviolet-C survival and normal DNA repair. Sequencing the xeroderma pigmentosum complementation group C cDNA of XP12TA and XP25TA revealed a homozygous deletion of two bases (del AT 669-670) in exon 5 with a new termination site 10 codons downstream that is expected to encode a truncated xeroderma pigmentosum complementation group C protein. Sequence analysis of the xeroderma pigmentosum complementation group C cDNA in cells from the parents found identical heterozygous mutations: one allele carries both the exon 5 frameshift and an exon 15 polymorphism and the other allele carries neither alteration. Cells from the unaffected brother had two normal xeroderma pigmentosum complementation group C alleles. This frameshift mutation in the xeroderma pigmentosum complementation group C gene led to reduced DNA repair with multiple skin cancers and early death. Sun protection delayed the onset of skin cancer and prolonged life in a sibling with the same mutation.
Slor
H
H
Department of Human Genetics and Molecular Medicine, Sackler Faculty of Medicine, Tel Aviv University, Israel.
Batko
S
S
Khan
S G
SG
Sobe
T
T
Emmert
S
S
Khadavi
A
A
Frumkin
A
A
Busch
D B
DB
Albert
R B
RB
Kraemer
K H
KH
D000328:Adult; D002470:Cell Survival / Q000528:radiation effects; D002648:Child; D002675:Child, Preschool; D004260:DNA Repair; D005192:Family Health; D005260:Female; D005347:Fibroblasts / Q000166:cytology; D016368:Frameshift Mutation; D005816:Genetic Complementation Test; D006801:Humans; D007557:Israel / Q000453:epidemiology; D008297:Male; D010375:Pedigree; D012333:RNA, Messenger / Q000378:metabolism; D017422:Sequence Analysis, DNA; D014466:Ultraviolet Rays; D014983:Xeroderma Pigmentosum / Q000453:epidemiology / Q000235:genetics*
D012333:RNA, Messenger