Table 2.

Summary of Molecular Genetic Testing Used in NDP-Related Retinopathies

Gene 1Test MethodProportion of Probands with a Pathogenic Variant Detectable by This Method
Affected MalesCarrier Females
NDPSequence analysis 295% 3, 480% 5
Deletion/duplication analysis 615% 715% 7
1.

See Table A. Genes and Databases for chromosome locus and protein. See Molecular Genetics for information on allelic variants detected in this gene.

2.

Sequence analysis detects variants that are benign, likely benign, of uncertain significance, likely pathogenic, or pathogenic. 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.

3.

Lack of amplification by PCR prior to sequence analysis can suggest a putative (multi)exon or whole-gene deletion on the X chromosome in affected males; confirmation may require additional testing by deletion/duplication analysis.

4.

Includes the 15% of pathogenic variants that are submicroscopic deletions involving all or part of NDP and adjacent genomic segments [Berger & Ropers 2001; Sims, unpublished].

5.

Sequence analysis of genomic DNA cannot detect deletion of one or more exons or the entire X-linked gene in a heterozygous female.

6.

Testing that identifies exon or whole-gene deletions/duplications not detectable by sequence analysis of the coding and flanking intronic regions of genomic DNA. Included in the variety of methods that may be used are: quantitative PCR, long-range PCR, multiplex ligation-dependent probe amplification (MLPA), and chromosomal microarray (CMA) that includes this gene/chromosome segment.

7.

Submicroscopic deletions involving all or part of NDP and adjacent genomic segments [Berger & Ropers 2001; Sims, unpublished].

From: NDP-Related Retinopathies

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