Peutz-Jeghers syndrome

Peutz-Jeghers syndrome is caused by mutations in the STK11 gene.  It is characterized by multiple Peutz-Jeghers type hamartomatous gastrointestinal polyps, mucocutaneous hyperpigmentation, and an increased risk for multiple cancer types, primarily of the gastrointestinal tract.

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Test Code: 2762 Test Name: STK11 specific site analysis TAT 7-14 days Gene: 1
Test Code: 2766 Test Name: STK11 seq and del/dup TAT 14-21 days Gene: 1

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Why Is This Important?

  1. Option to modify frequency and initial age of mammogram/breast MRI, colonoscopy, or other screening as appropriate
  2. Consideration of prophylactic mastectomy, as appropriate based on family history
  3. Identify at-risk family members 

When To Consider Testing

STK11 genetic testing is indicated when any of the following are present1:

  1. >2 histologically confirmed PJS-type hamartomatous polyps
  2. Any number of PJS-type polyps, with a family history of PJS in close relatives
  3. Characteristic mucocutaneous pigmentation, with a family history of PJS in close relatives
  4. Any number of PJS-type polyps, along with characteristic mucocutaneous pigmentation

Mutation Detection Rate

Genetic testing detects a pathogenic mutation in 94% of individuals meeting the above clinical diagnostic criteria.2 

Ambry’s STK11 testing is capable of detecting >99.9% of described mutations in the gene, when present (analytic sensitivity).

Test Description

STK11 coding exons 1-9 and well into the 5’ and 3’ ends of all the introns and untranslated regions are analyzed by sequencing. Gross deletion/duplication analysis determines gene copy number for coding exons 1-9. Clinically significant intronic findings beyond 5 base pairs are always reported. Intronic variants of unknown or unlikely clinical significance are not reported beyond 5 base pairs from the splice junction. Genomic deoxyribonucleic acid (gDNA) is isolated from the patient’s specimen using a standardized methodology and quantified. Sequence enrichment of the targeted coding exons and adjacent intronic nucleotides is carried out by incorporating the gDNA onto a microfluidics chip, along with primer pairs followed by polymerase chain reaction (PCR) and next generation sequencing (NGS). Sanger sequencing is performed for any regions missing, or with insufficient read depth coverage for reliable heterozygous variant detection. Suspect variant calls are verified by Sanger sequencing.  Gross deletion/duplication analysis of STK11 using read-depth from NGS data is also performed. Any copy number changes detected by NGS are confirmed by targeted chromosomal microarray and/or multiplex ligation-dependent probe amplification (MLPA).

 

1. Beggs AD, et al. Peutz-Jeghers syndrome: a systematic review and recommendations for management. Gut. 2010; 59:975-986. 

2. Aretz S et al. High proportion of large genomic STK11 deletions in Peutz-Jeghers syndrome. Human Mutation. 2005;26(6): 513-519. 

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