Cold Spring Harbor Molecular Case Studies: Bloom syndrome in a Mexican-American family with rhabdomyosarcoma: evidence of a Mexican founder mutation (Bishop, Chen, Tomlinson)

  1. Erin H. Sybouts1,2,11,
  2. Adam D. Brown1,2,8,11,
  3. Maria G. Falcon-Cantrill3,9,11,
  4. Martha H. Thomas1,10,
  5. Thomas DeNapoli4,5,
  6. Julie Voeller5,6,
  7. Yidong Chen1,7,
  8. Gail E. Tomlinson1,3 and
  9. Alexander J.R. Bishop1,2


Bloom syndrome is a rare autosomal recessive disorder with less than 300 cases reported in the literature. Bloom syndrome is characterized by chromosome instability, physical stigmata, growth deficiency, immunodeficiency, and a predisposition to cancer, most commonly leukemias, although solid tumors are reported as well. Bloom syndrome occurs in multiple ethnic groups with a higher incidence in persons of Ashkenazi Jewish origin. Few patients of Hispanic ethnicity have been reported. We report here a Mexican American family with a BLM pathogenic variant, c.2506_2507delAG, previously reported in a single patient from Mexico. In this family of four siblings, three have phenotypic features of Bloom syndrome, and BLM gene mutation was homozygous in these affected individuals. Our proband developed a rhabdomyosarcoma. Analysis of surrounding markers in the germline DNA revealed a common haplotype, suggesting a previously unrecognized founder mutation in the Hispanic population of Mexican origin.

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