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Sorting nexin 3 (SNX3) is disrupted in a patient with a translocation t(6;13)(q21;q12) and microcephaly,

V S Vervoort1, D Viljoen, R Smart

  • 1Greenwood Genetic Center, Greenwood, South Carolina 29646, USA.

Journal of Medical Genetics
|December 10, 2002
PubMed

Insights

Researchers investigated a rare genetic disorder, microcephaly, microphthalmia, ectrodactyly, and prognathism (MMEP), linked to a chromosome translocation. The sorting nexin 3 (SNX3) gene was disrupted, but further analysis revealed no mutations, suggesting other genetic factors may be involved.

Area of Science:

  • Genetics
  • Molecular Biology
  • Human Disease

Background:

  • A patient presented with microcephaly, microphthalmia, ectrodactyly, and prognathism (MMEP) and mental retardation.
  • This patient carried a de novo reciprocal t(6;13)(q21;q12) translocation, suggesting a potential genetic cause for the observed phenotype.

Purpose of the Study:

  • To identify the gene disrupted by the t(6;13) translocation in a patient with MMEP.
  • To investigate the role of the sorting nexin 3 (SNX3) gene in MMEP etiology.

Main Methods:

  • Fluorescence in situ hybridisation (FISH) to map translocation breakpoints.
  • Southern blot analysis and Inverse PCR to identify gene disruption.
  • Mutation screening (dHPLC, Southern blot) of SNX3 in another MMEP case.

Main Results:

  • The t(6;13) translocation breakpoint on chromosome 6 disrupted the SNX3 gene.
  • No additional rearrangements were found at the breakpoints on either chromosome.
  • Mutation screening of SNX3 in a second MMEP patient revealed no coding sequence mutations or deletions.

Conclusions:

  • The balanced t(6;13) translocation disrupted SNX3, making it a candidate gene for MMEP in the initial patient.
  • The absence of SNX3 mutations in a second MMEP case suggests genetic heterogeneity or a positional effect of the translocation.
  • Further investigation is needed to identify the causative gene(s) for MMEP, potentially involving genes near the translocation breakpoint or other genetic factors.

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