Different Interpretations of the Same Genetic Data

COL4A4 variant recently identified: lessons learned in variant interpretation-a case report

Background

Alport syndrome is a hereditary kidney disease characterized by hematuria and proteinuria. Although there have been reports of autosomal dominant COL4A4 variants, this is likely an underdiagnosed condition. Improved access to affordable genetic testing has increased the diagnosis of Alport syndrome. As genetic testing becomes ubiquitous, it is imperative that clinical nephrologists understand the benefits and challenges associated with clinical genetic testing.

Case Presentation

We present a family of Mexican descent with a heterozygous COL4A4 variant (c.5007delC, ClinVar accession numbers: SCV001580980.2, SCV001993731.1) not previously discussed in detail in the literature. The proband received a biopsy diagnosis suggestive of Fabry disease 18 years after she first developed hematuria and progressed to chronic kidney disease stage III. One year later, the proband was provisionally diagnosed with Alport syndrome after a variant of uncertain significance in the COL4A4 gene was identified following targeted family variant testing of her daughter. Upon review of the medical histories of the proband’s children and niece, all but one had the same variant. Of the four with the variant, three display clinical symptoms of hematuria, and/or proteinuria. The youngest of the four, only months old, has yet to exhibit clinical symptoms. Despite these findings there was a considerable delay in synthesizing this data, as patients were tested in different commercial genetic testing laboratories. Subsequently, understanding this family’s inheritance pattern, family history, and clinical symptoms, as well as the location of the COL4A4 variant resulted in the upgrade of the variant’s classification. Although the classification of this variant varied among different clinical genetic testing laboratories, the consensus was that this variant is likely pathogenic.

Conclusions

This COL4A4 variant (c.5007delC) not yet discussed in detail in the literature is associated with Alport syndrome. The inheritance pattern is suggestive of autosomal dominant inheritance. This report highlights the intricacies of variant interpretation and classification, the siloed nature of commercial genetic testing laboratories, and the importance of a thorough family history for proper variant interpretation. Additionally, the cases demonstrate the varied clinical presentations of Alport syndrome and suggest the utility of early screening, diagnosis, monitoring, and treatment.

The Challenge of Genetic Variants of Uncertain Clinical Significance : A Narrative Review

Genomic tests expand diagnostic and screening opportunities but also identify genetic variants of uncertain clinical significance (VUSs). Only a minority of VUSs are likely to prove pathogenic when later reassessed, but resolution of the uncertainty is rarely timely. That uncertainty adds complexity to clinical decision making and can result in harms and costs to patients and the health care system, including the time-consuming analysis required to interpret a VUS and the potential for unnecessary treatment and adverse psychological effects. Current efforts to improve variant interpretation will help reduce the scope of the problem, but the high prevalence of rare and novel variants in the human genome points to VUSs as an ongoing challenge. Additional strategies can help mitigate the potential harms of VUSs, including testing protocols that limit identification or reporting of VUSs, subclassification of VUSs according to the likelihood of pathogenicity, routine family-based evaluation of variants, and enhanced counseling efforts. All involve tradeoffs, and the appropriate balance of measures is likely to vary for different test uses and clinical settings. Cross-specialty deliberation and public input could contribute to systematic and broadly supported policies for managing VUSs.

Genetic Counseling and Testing in Pulmonary Arterial Hypertension

A subgroup of patients diagnosed with pulmonary arterial hypertension (PAH) carry transmissible pathogenic gene mutations. For many of these patients, the heritable nature of their disease can only be uncovered by genetic testing. Because identification of PAH patients who carry pathogenic gene mutations has important implications for other family members, genetic counseling and testing should be offered to patients diagnosed with idiopathic or familial PAH. This review describes the current state of genetic counseling and testing for patients diagnosed with PAH.