A mosaic PTEN mutation causing Cowden syndrome identified by deep sequencing.

[cowden syndrome]

Mosaic PTEN mutations are not well described in Cowden syndrome . We report a 40 -year -old woman with a clinical diagnosis of Cowden syndrome including Lhermitte-Duclos disease , who had a mosaic PTEN mutation detected by next -generation deep sequencing .Complete PTEN gene sequencing by the Sanger method and deletion /duplication analysis performed on DNA extracted from blood leukocytes at a commercial clinical laboratory did not identify a mutation . Because of high suspicion of a PTEN mutation , we repeated testing by next -generation sequencing using the ColoSeq assay , which sequences the entire PTEN locus at >320 -fold average coverage .ColoSeq identified a frameshift PTEN mutation (c .767 _768 delAG ) in 1 .7 % of sequencing reads from peripheral blood leukocytes (21 /1 ,184 reads ), which is below the limit of detection of most Sanger sequencing methods . The mutation was detected at full heterozygous levels in skin fibroblasts and a cerebellar tumor , and at approximately the 25 % level in colonic and endocervical mucosa , confirming somatic mosaicism .Our report highlights the power of deep next -generation sequencing to identify mosaic mutations that can be missed by traditional less sensitive approaches . We speculate that mosaic PTEN mutations are more common in Cowden syndrome than previously described .

Diseases
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Diseases presenting "full heterozygous levels in skin" symptom

cowden syndrome

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