Genomic Testing in Patients with Kidney Failure of an Unknown Cause: a National Australian Study.

BACKGROUND: The cause of kidney failure is unknown in approximately 10% of patients with stage 5 chronic kidney disease (CKD). For those who first present to nephrology care with kidney failure, standard investigations of serology, imaging, urinalysis and kidney biopsy are limited differentiators of etiology. We aimed to determine the diagnostic utility of whole-genome sequencing (WGS) with analysis of a broad kidney gene panel in patients with kidney failure of unknown cause. METHODS: We prospectively recruited 100 participants who reached CKD stage 5 at 50 years of age and had an unknown cause of kidney failure after standard investigation. Clinically-accredited WGS was performed in this national cohort after genetic counselling. The primary analysis was targeted to 388 kidney-related genes with second-tier genome-wide and mitochondrial analysis. RESULTS: The cohort was 61% male and the average age of participants at stage 5 CKD was 32 years (9 months to 50 years). A genetic diagnosis was made in 25% of participants. Disease-causing variants were identified across autosomal dominant tubulointerstitial kidney disease (6), glomerular disorders (4), ciliopathies (3), tubular disorders (2), Alport syndrome (4) and mitochondrial disease (1). Most diagnoses (80%) were in autosomal dominant, X-linked or mitochondrial conditions (UMOD; COL4A5; INF2; CLCN5; TRPC6; COL4A4; EYA1; HNF1B; WT1; NBEA; m.3243A>G). Patients with a family history of CKD were more likely to have a positive result (OR 3.29, 95% CI 1.10-11.29). Thirteen percent of participants without a CKD family history had a positive result. In those who first presented in stage 5 CKD, WGS with broad analysis of a curated kidney-disease gene panel was diagnostically more informative than kidney biopsy, with biopsy being inconclusive in 24 of 25 participants. CONCLUSIONS: In this prospectively ascertained Australian cohort, we identified a genetic diagnosis in 25% of patients with kidney failure of unknown cause.

Inherited variants in CHD3 show variable expressivity in Snijders Blok-Campeau syndrome.

PURPOSE: Common diagnostic next-generation sequencing strategies are not optimized to identify inherited variants in genes associated with dominant neurodevelopmental disorders as causal when the transmitting parent is clinically unaffected, leaving a significant number of cases with neurodevelopmental disorders undiagnosed. METHODS: We characterized 21 families with inherited heterozygous missense or protein-truncating variants in CHD3, a gene in which de novo variants cause Snijders Blok-Campeau syndrome. RESULTS: Computational facial and Human Phenotype Ontology-based comparisons showed that the phenotype of probands with inherited CHD3 variants overlaps with the phenotype previously associated with de novo CHD3 variants, whereas heterozygote parents are mildly or not affected, suggesting variable expressivity. In addition, similarly reduced expression levels of CHD3 protein in cells of an affected proband and of healthy family members with a CHD3 protein-truncating variant suggested that compensation of expression from the wild-type allele is unlikely to be an underlying mechanism. Notably, most inherited CHD3 variants were maternally transmitted. CONCLUSION: Our results point to a significant role of inherited variation in Snijders Blok-Campeau syndrome, a finding that is critical for correct variant interpretation and genetic counseling and warrants further investigation toward understanding the broader contributions of such variation to the landscape of human disease.

Genetic Counseling in the Era of Genomics: What's all the Fuss about?

As genomic sequencing becomes more widely available in clinical settings for diagnostic purposes, a number of genetic counseling issues are gaining precedence. The ability to manage these issues will be paramount as genetic and non-genetic healthcare professionals navigate the complexities of using genomic technologies to facilitate diagnosis and inform patient management. Counseling issues arising when counseling for diagnostic genomic sequencing were identified by four genetic counselors with 10 years of collective experience providing genetic counseling in this setting. These issues were discussed and refined at a meeting of genetic counselors working in clinical genomics settings in Melbourne, Australia. Emerging counseling issues, or variations of established counseling issues, were identified from the issues raised. Illustrative cases were selected where pre- and post-test genetic counseling was provided in clinical settings to individuals who received singleton or trio WES with targeted analysis. Counseling issues discussed in this paper include a reappraisal of how genetic counselors manage hope in the genomic era, informed consent for secondary use of genomic data, clinical reanalysis of genomic data, unexpected or unsolicited secondary findings, and trio sequencing. The authors seek to contribute to the evolving understanding of genetic counseling for diagnostic genomic sequencing through considering the applicability of existing genetic counseling competencies to managing emerging counseling issues and discussing genetic counseling practice implications.

"It wasn't a disaster or anything": Parents' experiences of their child's uncertain chromosomal microarray result.

Chromosomal microarray is an increasingly utilized diagnostic test, particularly in the pediatric setting. However, the clinical significance of copy number variants detected by this technology is not always understood, creating uncertainties in interpreting and communicating results. The aim of this study was to explore parents' experiences of an uncertain microarray result for their child. This research utilized a qualitative approach with a phenomenological methodology. Semi-structured interviews were conducted with nine parents of eight children who received an uncertain microarray result for their child, either a 16p11.2 microdeletion or 15q13.3 microdeletion. Interviews were transcribed verbatim and thematic analysis was used to identify themes within the data. Participants were unprepared for the abnormal test result. They had a complex perception of the extent of their child's condition and a mixed understanding of the clinical relevance of the result, but were accepting of the limitations of medical knowledge, and appeared to have adapted to the result. The test result was empowering for parents in terms of access to medical and educational services; however, they articulated significant unmet support needs. Participants expressed hope for the future, in particular that more information would become available over time. This research has demonstrated that parents of children who have an uncertain microarray result appeared to adapt to uncertainty and limited availability of information and valued honesty and empathic ongoing support from health professionals. Genetic health professionals are well positioned to provide such support and aid patients' and families' adaptation to their situation as well as promote empowerment. © 2016 Wiley Periodicals, Inc.

Heritable GATA2 mutations associated with familial myelodysplastic syndrome and acute myeloid leukemia.

We report the discovery of GATA2 as a new myelodysplastic syndrome (MDS)-acute myeloid leukemia (AML) predisposition gene. We found the same, previously unidentified heterozygous c.1061C>T (p.Thr354Met) missense mutation in the GATA2 transcription factor gene segregating with the multigenerational transmission of MDS-AML in three families and a GATA2 c.1063_1065delACA (p.Thr355del) mutation at an adjacent codon in a fourth MDS family. The resulting alterations reside within the second zinc finger of GATA2, which mediates DNA-binding and protein-protein interactions. We show differential effects of the mutations on the transactivation of target genes, cellular differentiation, apoptosis and global gene expression. Identification of such predisposing genes to familial forms of MDS and AML is critical for more effective diagnosis and prognosis, counseling, selection of related bone marrow transplant donors and development of therapies.