Unintended diagnosis of Von Hippel Lindau syndrome using Array Comparative Genomic Hybridization (CGH): counseling challenges arising from unexpected information

Genetic Testing in Neurodevelopmental Disorders

Neurodevelopmental disorders are the most prevalent chronic medical conditions encountered in pediatric primary care. In addition to identifying appropriate descriptive diagnoses and guiding families to evidence-based treatments and supports, comprehensive care for individuals with neurodevelopmental disorders includes a search for an underlying etiologic diagnosis, primarily through a genetic evaluation. Identification of an underlying genetic etiology can inform prognosis, clarify recurrence risk, shape clinical management, and direct patients and families to condition-specific resources and supports. Here we review the utility of genetic testing in patients with neurodevelopmental disorders and describe the three major testing modalities and their yields - chromosomal microarray, exome sequencing (with/without copy number variant calling), and FMR1 CGG repeat analysis for fragile X syndrome. Given the diagnostic yield of genetic testing and the potential for clinical and personal utility, there is consensus that genetic testing should be offered to all patients with global developmental delay, intellectual disability, and/or autism spectrum disorder. Despite this recommendation, data suggest that a minority of children with autism spectrum disorder and intellectual disability have undergone genetic testing. To address this gap in care, we describe a structured but flexible approach to facilitate integration of genetic testing into clinical practice across pediatric specialties and discuss future considerations for genetic testing in neurodevelopmental disorders to prepare pediatric providers to care for patients with such diagnoses today and tomorrow.

CGH analysis in Colombian patients: findings of 1374 arrays in a seven-year study

Background

Array-based comparative genome hybridization (array CGH) is a first-line test used in the genetic evaluation of individuals with multiple anomalies, developmental delays, and cognitive deficits. In this study, we analyzed clinical indications and findings of array CGH tests of Colombian individuals forwarded to a reference laboratory over a period of seven years in order to evaluate the diagnostic performance of the test in our population.

Results

The results of 1374 array CGH analyses of Colombian individuals were referred to the Andean Reference Institute in Colombia (Instituto de Referencia Andino) during a 7-year period (2009–2015). Chromosomal imbalances were detected in 488 cases (35%), whereas 121 cases were classified as nonpathogenic variants, 65 cases (4.7%) were classified as variants of uncertain significance, and 302 cases (22%) were classified as abnormal or pathogenic. The most common findings in the abnormal and/or pathogenic set were deletions, followed by duplications and complex rearrangements. Variants in the carrier status of autosomal recessive diseases were identified as incidental findings in 29 subjects (2%).

Conclusions

Clinical indications preceding the referral of aCGH in Colombian patients are not standardized and result in unexpected pathogenic variants as well as secondary findings that need careful interpretation. Development of local infrastructure will probably improve the communication between all stakeholders, to ensure accurate clinical diagnoses.

Predictive genetic testing in children: constitutional mismatch repair deficiency cancer predisposing syndrome

Biallelic germline mutations in mismatch repair genes predispose to constitutional mismatch repair deficiency syndrome (CMMR-D). The condition is characterized by a broad spectrum of early-onset tumors, including hematological, brain and bowel and is frequently associated with features of Neurofibromatosis type 1. Few definitive screening recommendations have been suggested and no published reports have described predictive testing. We report on the first case of predictive testing for CMMR-D following the identification of two non-consanguineous parents, with the same heterozygous mutation in MLH1: c.1528C > T. The genetic counseling offered to the family, for their two at-risk daughters, is discussed with a focus on the ethical considerations of testing children for known cancer-causing variants. The challenges that are encountered when reporting on heterozygosity in a child younger than 18 years (disclosure of carrier status and risk for Lynch syndrome), when discovered during testing for homozygosity, are addressed. In addition, the identification of CMMR-D in a three year old, and the recommended clinical surveillance that was proposed for this individual is discussed. Despite predictive testing and presymptomatic screening, the sudden death of the child with CMMR-D syndrome occurred 6 months after her last surveillance MRI. This report further highlights the difficulty of developing guidelines, as a result of the rarity of cases and diversity of presentation.

Genetic medicine and incidental findings: it is more complicated than deciding whether to disclose or not

PURPOSE

The aim of this study was to explore the clinical management of incidental findings. Advances in the speed and sensitivity of genetic technologies have not only improved the diagnostic rate but also result in an increase in unanticipated diagnoses. Recent debate on such "incidental findings" has considered whether or not to actively search for and, then, disclose incidental findings. In our experience, many incidental findings need to be investigated in family members before their clinical significance can be assessed. This adds complexity to the debate about disclosure.

METHODS

Using anonymized clinical examples, we illustrate the downstream implications when a result reveals an incidental abnormality of potential clinical significance that is not related to the reasons for doing the test.

RESULTS

Our examples illustrate that the determination of clinical significance may require participation of family members in both testing and surveillance.

CONCLUSION

The need to investigate multiple relatives in order to decide whether or not a finding is clinically significant has implications for consent and disclosure practices. Communication with, and care for, relatives who have no reason to suspect particular diagnoses is a challenge for any health-care service. These costs also need to be taken into account as genetic testing enters mainstream medicine.

Incidental findings from clinical genome-wide sequencing: a review

There are several unresolved challenges associated with the clinical application of genome-wide sequencing technologies. One of the most discussed issues is incidental findings (IF), which are defined as discoveries made as a result of genetic testing that are unrelated to the indication for the test. The discussion surrounding IF began in the context of research, which we have used to frame consideration of IF in the clinical context. There is growing consensus that analytically valid and medically actionable IF should be offered to patients, but whether and to what extent clinicians should disclose other kinds of IF is debated. While others have systematically reviewed the literature concerning genetic IF, previous reviews focus on ethical and research-related issues and do not consider the implications for the genetic counseling profession specifically. This review discusses the practical considerations, ethical concerns and genetic counseling issues related to IF, with a particular focus on clinical genome-wide sequencing. To date, the bulk of the literature with respect to IF in the clinical context consists of commentaries, reviews and case reports. There is a need for more empirical studies to provide a foundation for institutional protocols and evidence-based clinical practice standards.