Table 1.

Molecular Genetic Testing Used in X-Linked Hyper IgM Syndrome

Gene 1Test MethodVariants Detected 2Variant Detection Frequency by Test Method 3
Affected MalesCarrier Females
CD40LGSequence analysis 4Sequence variants 595% 4, 595% 6
Deletion/duplication analysis 7(Multi)exon or whole-gene deletion5%5% 8
1.
2.

See Molecular Genetics for information on allelic variants.

3.

The ability of the test method used to detect a pathogenic variant that is present in the indicated gene

4.

Sequence analysis detects variants that are benign, likely benign, of unknown 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.

5.

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

6.

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

7.

Testing that identifies exon or whole-gene deletions/duplications not readily 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.

8.

Although it is technically feasible for this method to detect a deletion in a carrier female whether or not the deletion has previously been identified in the family, some laboratories may offer deletion testing only to those at-risk women whose family-specific deletion is known.

From: X-Linked Hyper IgM Syndrome

Cover of GeneReviews®
GeneReviews® [Internet].
Adam MP, Ardinger HH, Pagon RA, et al., editors.
Seattle (WA): University of Washington, Seattle; 1993-2018.
Copyright © 1993-2018, University of Washington, Seattle. GeneReviews is a registered trademark of the University of Washington, Seattle. All rights reserved.

GeneReviews® chapters are owned by the University of Washington. Permission is hereby granted to reproduce, distribute, and translate copies of content materials for noncommercial research purposes only, provided that (i) credit for source (http://www.genereviews.org/) and copyright (© 1993-2018 University of Washington) are included with each copy; (ii) a link to the original material is provided whenever the material is published elsewhere on the Web; and (iii) reproducers, distributors, and/or translators comply with the GeneReviews® Copyright Notice and Usage Disclaimer. No further modifications are allowed. For clarity, excerpts of GeneReviews chapters for use in lab reports and clinic notes are a permitted use.

For more information, see the GeneReviews® Copyright Notice and Usage Disclaimer.

For questions regarding permissions or whether a specified use is allowed, contact: ude.wu@tssamda.

NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.