Table 1.

Molecular Genetic Testing Used in Adenine Phosphoribosyltransferase Deficiency

Gene 1MethodProportion of Probands with a Pathogenic Variant 2 Detectable by Method
APRT Sequence analysis 3, 4~87% 5
Gene-targeted deletion/duplication analysis 6Rare 7
1.
2.

See Molecular Genetics for information on allelic 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.

Approximately 50 pathogenic variants have been identified in the coding region of APRT in >400 affected individuals from >25 countries, including at least 200 individuals from Japan (see Molecular Genetics).

5.

DNA sequence analysis of the APRT coding region and intron/exon junctions from 31 affected individuals (62 chromosomes) with complete APRT deficiency failed to identify 13% of the mutated alleles [Bollée et al 2010]. It remains to be determined whether pathogenic variants occur outside of the sequenced regions or are due to epigenetic changes.

6.

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.

7.

Rare deletions of both APRT and GALNS, as well as a complex 254-bp deletion with 8-bp insertion, have been described (see Molecular Genetics).

From: Adenine Phosphoribosyltransferase Deficiency

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