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The 57 kb deletion in cystinosis patients extends into TRPV1 causing dysregulation of transcription in peripheral blood mononuclear cells
  1. Katy A Freed1,
  2. John Blangero1,
  3. Tom Howard2,
  4. Matthew P Johnson1,
  5. Joanne E Curran1,
  6. Yvonne R Garcia1,
  7. Hao-Chang Lan1,
  8. Hanna E Abboud3,
  9. Eric K Moses1
  1. 1Department of Genetics, Texas Biomedical Research Institute, San Antonio, Texas, USA
  2. 2Department of Pathology and Laboratory Medicine, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, USA
  3. 3Department of Medicine, University of Texas Health Science Center, San Antonio, Texas, USA
  1. Correspondence to Katy A Freed, Department of Genetics, Texas Biomedical Research Institute, P.O. Box 760549, San Antonio, Texas, 78245-0549, USA; kfreed{at}; kfreed{at}


Background Cystinosis is an autosomal recessive disease characterised by the abnormal accumulation of lysosomal cystine. Mutations in the cystinosin gene (CTNS) represent known causes for the disease. The major cystinosis mutation is a 57 kb deletion on human chromosome 17p13 that removes the majority of CTNS and the entire adjacent gene, CARKL/SHPK.

Objectives In order to identify other genes that may influence the cystinosis pathobiological pathway, peripheral blood mononuclear cells (PBMC) were collected from cystinosis family members, and DNA and RNA extracted.

Results Using whole genome transcriptional profiling, transient receptor potential vanilloid 1 (TRPV1) was found to be differentially expressed in association with cystinosis. This was verified using TaqMan qRT-PCR. There was a 72% reduction in PBMC TRPV1 mRNA levels in cystinosis individuals homozygous for the 57 kb deletion (n=6) compared to unaffected individuals without the deletion (n=6) (p=0.002). TRPV1 is a sensory receptor located on chromosome 17p13, adjacent to CARKL/SHPK. It was ascertained that the 57 kb deletion extends from exon 10 of CTNS, upstream through CARKL/SHPK, to intron 2 of TRPV1, thus deleting the first two non-coding exons.

Conclusion This is the first study to report that the 57 kb deletion extends into the TRPV1 gene causing dysregulation of transcription in PBMC isolated from cystinosis patients.

  • Cystinosis
  • TRPV1
  • 57-kb deletion
  • CTNS
  • gene expression
  • metabolic disorders
  • genetics
  • molecular genetics

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  • Funding Financial support for this project has been generously provided by the Cystinosis Research Foundation and the Azar and Shepperd families of San Antonio. This investigation was conducted in facilities constructed with support from Research Facilities Improvement Program grants C06 RR017515 from the National Center for Research Resources, National Institutes of Health. There was no involvement in the study design, analysis or interpretation of the data by these funding sources. Cystinosis Research Foundation18802 Bardeen AvenueIrvine, CA 92612.

  • Competing interests None.

  • Ethics approval This study was conducted with the approval of the Institutional Review Board of the University of Texas Health Science Center at San Antonio.

  • Provenance and peer review Not commissioned; externally peer reviewed.