Table 1.

Molecular Genetic Testing Used in Juvenile Polyposis Syndrome

Gene 1Proportion of JPS Attributed to Pathogenic Variants in GeneProportion of Pathogenic Variants 2 Detectable by Method
Sequence analysis 3Gene-targeted deletion/duplication analysis 4
BMPR1A 28% 569%-85% 5, 615% 5
SMAD4 27% 583% 517% 5
Unknown 745%NA

NA = not applicable

1.
2.

See Molecular Genetics for information on variants detected in this gene.

3.

Sequence analysis detects variants that are benign, likely benign, of uncertain significance, likely pathogenic, or pathogenic. Variants may include small intragenic deletions/insertions and missense, nonsense, and splice site variants; typically, exon or whole-gene deletions/duplications are not detected. For issues to consider in interpretation of sequence analysis results, click here.

4.

Gene-targeted deletion/duplication analysis detects intragenic deletions or duplications. Methods used may include a range of techniques such as quantitative PCR, long-range PCR, multiplex ligation-dependent probe amplification (MLPA), and a gene-targeted microarray designed to detect single-exon deletions or duplications.

5.
6.

Sequence analysis of the BMPR1A promoter region identified a pathogenic variant in 6/65 individuals with JPS who did not have a BMPR1A or SMAD4 pathogenic variant identified on sequencing of the coding regions or deletion/duplication testing [Calva-Cerqueira et al 2010]. Sequence analysis that includes the promoter region increases the proportion of pathogenic variants detected by sequencing.

7.

Two individuals with early-onset JPS have been found to have ENG pathogenic variants. Neither had clinical symptoms of HHT, which is known to be associated with ENG pathogenic variants; however, neither had yet reached the age at which symptoms of HHT commonly manifest [Sweet et al 2005, Howe et al 2007].

From: Juvenile Polyposis Syndrome

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