Table 1.

Molecular Genetic Testing Used in Peters Plus Syndrome

Gene 1MethodProportion of Probands with Pathogenic
Variants 2 Detectable by Method
B3GLCT Sequence analysis 335% 4-100% 5, 6
Gene-targeted deletion/duplication analysis 74 individuals 8
1.

See Table A. Genes and Databases for chromosome locus and protein.

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.

Nine of 26 affected individuals tested, as identified by the Laboratory of Diagnostic Genome Analysis, Leiden, The Netherlands. Note: This is a clinically heterogeneous group.

5.

Twenty of 20 affected individuals tested, as identified by Lesnik Oberstein et al [2006]. This cohort is clinically well described.

6.

Most affected individuals tested to date are homozygous for a splice site pathogenic variant in intron 8 (c.660+1G>A) [Lesnik Oberstein et al 2006]. However, several other loss-of-function variants have been identified, including pathogenic missense variants located in the putative catalytic domain of the enzyme.

7.

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.

8.

Lesnik Oberstein et al [2006] described two brothers with a ~1.5-Mb contiguous gene deletion on their maternal allele that included B3GLCT. The proximal deletion breakpoint is between exons 7 and 8 of B3GLCT; the distal breakpoint is between exons 13 and 14 of BRCA2. Haldeman-Englert et al [2009] also reported a large deletion including all of B3GLCT. The paternal allele harbored a pathogenic single-nucleotide variant. Within the Laboratory of Diagnostic Genome Analysis, Leiden, The Netherlands, a heterozygous deletion of only exon 7 was identified; the other allele harbored the common intron 8 splice site pathogenic variant [Author, personal communication].

From: Peters Plus Syndrome

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