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J Med Genet 38:615-616 doi:10.1136/jmg.38.9.615
  • Letters to the editor

A G339R mutation in the CTNS gene is a common cause of nephropathic cystinosis in the south western Ontario Amish Mennonite population

  1. C Anthony Rupara,b,c,d,
  2. Douglas Matsellb,
  3. Susan Surryb,
  4. Victoria Siub
  1. a J Med Genet 2001; 38 :615–616 Department of Biochemistry, University of Western Ontario, London, ON, Canada, bDepartment of Paediatrics, University of Western Ontario, London, ON, Canada, cChild Health Research Institute, University of Western Ontario, London, ON, Canada, dChild and Parent Resource Institute, University of Western Ontario, London, ON, Canada
  1. Dr Rupar, Biochemical Genetics Laboratory, CPRI, 600 Sanatorium Road, London, Ontario, Canada N6H 3W7,trupar{at}julian.uwo.ca

    Editor—Nephropathic cystinosis (MIM 219800) is a rare autosomal recessively inherited lysosomal storage disorder with a newborn incidence of about 1 in 100 000-200 000 in the general population (OMIM). Cystine accumulates in lysosomes because of dysfunctional cystinosin mediated transport of cystine out of lysosomes. The accumulation of cystine results in damage to several organs with renal damage being the most pronounced in the first decade of life. Patients with cystinosis experience both tubular dysfunction (renal Fanconi syndrome) and glomerular deterioration. Renal Fanconi syndrome usually occurs within the first year of life with glomerular deterioration progressing throughout the first decade of life resulting in end stage renal failure.1

    The CTNS gene was mapped to chromosome 17p13 and subsequently isolated and characterised to have 12 exons spanning 23 kb of genomic DNA.2 3 The most common mutation that causes cystinosis is a large deletion that encompasses exons 1-10.4 Originally, this deletion was described as 65 kb long but the size has been recently refined to 57 257 bases.5 Forty four percent of 108 American based patients with nephropathic cystinosis were homozygous for this deletion.6

    At least seven children in the Old Order …