The Invitae Hyperprolinemia panel analyzes two genes, ALDH4A1 and PRODH, which are known to cause hyperprolinemia—excess proline accumulation in the body. There are two types of hyperprolinemia, I and II. Genetic testing of the genes in this panel may confirm a diagnosis and help guide treatment and management decisions.
Hyperprolinemia type I (HPI) is caused by pathogenic variants in the PRODH gene, which codes for the enzyme proline oxidase (POX). POX breaks proline down into pyrroline-5-carboxylate. Hyperprolinemia type II (HPII) is caused by pathogenic variants in the ALDH4A1 gene, which codes for the enzyme 1-pyrroline-5-carboxylate dehydrogenase (P5CDh). P5CDh breaks pyrroline-5-carboxylate down into glutamate. Both enzyme deficiencies cause elevated levels of proline in the body.
With both types of hyperprolinemia, elevated proline levels are detected upon newborn screening. Most individuals with pathogenic variants in PRODH and ALDH4A1 are asymptomatic, but some have seizures, cognitive issues, and psychiatric manifestations. Nephropathy has been reported in HPI. Patients with HPII are most often asymptomatic, but some affected individuals may have febrile seizures and intellectual disability. Patients with HPI and HPII will have elevated proline levels in the blood, even in asymptomatic individuals. Hyperprolinemia can also occur in liver disease; this type is not due to pathogenic variants in the genes.
Hyperprolinemia is inherited in an autosomal recessive manner.
The prevalence of hyperprolinemia is unknown because most individuals are asymptomatic.
This test may be considered for individuals who present with elevated proline levels in blood, cerebrospinal fluid, or urine.
Invitae is a College of American Pathologists (CAP)-accredited and Clinical Laboratory Improvement Amendments (CLIA)-certified clinical diagnostic laboratory performing full-gene sequencing and deletion/duplication analysis using next-generation sequencing technology (NGS).
Our sequence analysis covers clinically important regions of each gene, including coding exons, +/- 10 base pairs of adjacent intronic sequence in the transcript listed below. In addition, analysis covers the select non-coding variants specifically defined in the table below. Any variants that fall outside these regions are not analyzed. Any specific limitations in the analysis of these genes are also listed in the table below.
Based on validation study results, this assay achieves >99% analytical sensitivity and specificity for single nucleotide variants, insertions and deletions <15bp in length, and exon-level deletions and duplications. Invitae's methods also detect insertions and deletions larger than 15bp but smaller than a full exon but sensitivity for these may be marginally reduced. Invitae’s deletion/duplication analysis determines copy number at a single exon resolution at virtually all targeted exons. However, in rare situations, single-exon copy number events may not be analyzed due to inherent sequence properties or isolated reduction in data quality. Certain types of variants, such as structural rearrangements (e.g. inversions, gene conversion events, translocations, etc.) or variants embedded in sequence with complex architecture (e.g. short tandem repeats or segmental duplications), may not be detected. Additionally, it may not be possible to fully resolve certain details about variants, such as mosaicism, phasing, or mapping ambiguity. Unless explicitly guaranteed, sequence changes in the promoter, non-coding exons, and other non-coding regions are not covered by this assay. Please consult the test definition on our website for details regarding regions or types of variants that are covered or excluded for this test. This report reflects the analysis of an extracted genomic DNA sample. In very rare cases, (circulating hematolymphoid neoplasm, bone marrow transplant, recent blood transfusion) the analyzed DNA may not represent the patient's constitutional genome.
|Gene||Transcript reference||Sequencing analysis||Deletion/Duplication analysis|