Deletion of the telomerase reverse transcriptase gene and haploinsufficiency of telomere maintenance in Cri du chat syndrome.
Cri du chat syndrome (CdCS) results from loss of the distal portion of chromosome 5p, where the telomerase reverse transcriptase (hTERT) gene is localized (5p15.33). hTERT is the rate-limiting component for telomerase activity that is essential for telomere-length maintenance and sustained cell proliferation. Here, we show that a concomitant deletion of the hTERT allele occurs in all 10 patients with CdCS whom we examined. Induction of hTERT mRNA in proliferating lymphocytes derived from five of seven patients was lower than that in unaffected control individuals (P<.05). The patient lymphocytes exhibited shorter telomeres than age-matched unaffected individuals (P<.0001). A reduction in replicative life span and a high rate of chromosome fusions were observed in cultured patient fibroblasts. Reconstitution of telomerase activity by ectopic expression of hTERT extended the telomere length, increased the population doublings, and prevented the end-to-end fusion of chromosomes. We conclude that hTERT is limiting and haploinsufficient for telomere maintenance in humans in vivo. Accordingly, the hTERT deletion may be one genetic element contributing to the phenotypic changes in CdCS.
Zhang
Anju
A
Department of Pathology and Oncology, Karolinska Institutet and Hospital, Stockholm, Sweden.
Zheng
Chengyun
C
Hou
Mi
M
Lindvall
Charlotta
C
Li
Ke-Jun
KJ
Erlandsson
Fredrik
F
Björkholm
Magnus
M
Gruber
Astrid
A
Blennow
Elisabeth
E
Xu
Dawei
D
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D003410:Cri-du-Chat Syndrome / Q000235:genetics*; D004268:DNA-Binding Proteins; D005260:Female; D017353:Gene Deletion; D006801:Humans; D007223:Infant; D007621:Karyotyping; D008297:Male; D008969:Molecular Sequence Data; D019098:Telomerase / Q000235:genetics*; D016615:Telomere / Q000235:genetics*
D004268:DNA-Binding Proteins; D019098:Telomerase