Allelic phenotype values: a model for genotype-based phenotype prediction in phenylketonuria
The nature of phenylalanine hydroxylase (PAH) variants determines residual enzyme activity, which modifies the clinical phenotype in phenylketonuria (PKU). We exploited the statistical power of a large genotype database to determine the relationship between genotype and phenotype in PKU. A total of...
Saved in:
| Main Authors: | , , , , , , |
|---|---|
| Format: | Article (Journal) |
| Language: | English |
| Published: |
2019
|
| In: |
Genetics in medicine
Year: 2018, Volume: 21, Issue: 3, Pages: 580-590 |
| ISSN: | 1530-0366 |
| DOI: | 10.1038/s41436-018-0081-x |
| Online Access: | Verlag, Volltext: https://doi.org/10.1038/s41436-018-0081-x Verlag, Volltext: https://www.nature.com/articles/s41436-018-0081-x 
|
| Author Notes: | Sven F. Garbade, Nan Shen, Nastassja Himmelreich, Dorothea Haas, Friedrich K. Trefz, Georg F. Hoffmann, Peter Burgard, Nenad Blau |
| Summary: | The nature of phenylalanine hydroxylase (PAH) variants determines residual enzyme activity, which modifies the clinical phenotype in phenylketonuria (PKU). We exploited the statistical power of a large genotype database to determine the relationship between genotype and phenotype in PKU. A total of 9336 PKU patients with 2589 different genotypes, carrying 588 variants, were investigated using an allelic phenotype value (APV) algorithm. We identified 251 0-variants encoding inactive PAH, and assigned APVs (0 = classic PKU; 5 = mild PKU; 10 = mild hyperphenylalaninaemia) to 88 variants in PAH-functional hemizygous patients. The genotypic phenotype values (GPVs) were set equal to the higher-APV allele, which was assumed to be dominant over the lower-APV allele and to determine the metabolic phenotype. GPVs for 8872 patients resulted in cut-off ranges of 0.0-2.7 for classic PKU, 2.8-6.6 for mild PKU and 6.7-10.0 for mild hyperphenylalaninaemia. Genotype-based phenotype prediction was 99.2% for classic PKU, 46.2% for mild PKU and 89.5% for mild hyperphenylalaninaemia. The relationships between known pretreatment blood phenylalanine levels and GPVs (n = 4217), as well as tetrahydrobiopterin responsiveness and GPVs (n = 3488), were significant (both P < 0.001). APV and GPV are powerful tools to investigate genotype-phenotype associations, and can be used for genetic counselling of PKU families. |
|---|---|
| Item Description: | Published: 12 July 2018 Gesehen am 05.07.2019 |
| Physical Description: | Online Resource |
| ISSN: | 1530-0366 |
| DOI: | 10.1038/s41436-018-0081-x |