Noninvasive Prenatal Detection of Trisomy 21 by Targeted Semiconductor Sequencing: A Technical Feasibility Study.

OBJECTIVE: To develop an alternate noninvasive prenatal testing method for the assessment of trisomy 21 (T21) using a targeted semiconductor sequencing approach. METHODS: A customized AmpliSeq panel was designed with 1,067 primer pairs targeting specific regions on chromosomes 21, 18, 13, and others. A total of 235 samples, including 30 affected with T21, were sequenced with an Ion Torrent Proton sequencer, and a method was developed for assessing the probability of fetal aneuploidy via derivation of a risk score. RESULTS: Application of the derived risk score yields a bimodal distribution, with the affected samples clustering near 1.0 and the unaffected near 0. For a risk score cutoff of 0.345, above which all would be considered at "high risk," all 30 T21-positive pregnancies were correctly predicted to be affected, and 199 of the 205 non-T21 samples were correctly predicted. The average hands-on time spent on library preparation and sequencing was 19 h in total, and the average number of reads of sequence obtained was 3.75 million per sample. CONCLUSION: With the described targeted sequencing approach on the semiconductor platform using a custom-designed library and a probabilistic statistical approach, we have demonstrated the feasibility of an alternate method of assessment for fetal T21.

A novel NaV1.5 voltage sensor mutation associated with severe atrial and ventricular arrhythmias.

BACKGROUND: Inherited autosomal dominant mutations in cardiac sodium channels (NaV1.5) cause various arrhythmias, such as long QT syndrome and Brugada syndrome. Although dozens of mutations throughout the protein have been reported, there are few reported mutations within a voltage sensor S4 transmembrane segment and few that are homozygous. Here we report analysis of a novel lidocaine-sensitive recessive mutation, p.R1309H, in the NaV1.5 DIII/S4 voltage sensor in a patient with a complex arrhythmia syndrome. METHODS AND RESULTS: We expressed the wild type or mutant NaV1.5 heterologously for analysis with the patch-clamp and voltage clamp fluorometry (VCF) techniques. p.R1309H depolarized the voltage-dependence of activation, hyperpolarized the voltage-dependence of inactivation, and slowed recovery from inactivation, thereby reducing the channel availability at physiologic membrane potentials. Additionally, p.R1309H increased the "late" Na(+) current. The location of the mutation in DIIIS4 prompted testing for a gating pore current. We observed an inward current at hyperpolarizing voltages that likely exacerbates the loss-of-function defects at resting membrane potentials. Lidocaine reduced the gating pore current. CONCLUSIONS: The p.R1309H homozygous NaV1.5 mutation conferred both gain-of-function and loss-of-function effects on NaV1.5 channel activity. Reduction of a mutation-induced gating pore current by lidocaine suggested a therapeutic mechanism.

Activity intensity during free-living activities in children and adolescents with inherited arrhythmia syndromes: assessment by combined accelerometer and heart rate monitor.

BACKGROUND: International guidelines recommend restriction of activities for many children and adolescents with inherited arrhythmia syndromes to moderate activity (<7 metabolic equivalents [METs]). We hypothesized that moderate levels of intensity would be exceeded during free-living daily activity in these individuals when assessed objectively by combined heart rate and accelerometry monitor (Actiheart). METHODS AND RESULTS: Participants wore the Actiheart for ≤7 days on 2 occasions after a maximal exercise test that was used to calibrate the monitor individually against intensity levels. Of 16 participants, 13 (81%) had long QT syndrome, 9 (56%) were female, and median age was 12 years. Monitors were worn for a median (range) of 13 (6-14) days, and a mean (SD) of 11.3 (1.7) hours per day. Vigorous (7 MET) and very vigorous (10 MET) thresholds were exceeded by 15 and 13 participants, respectively. The median (interquartile range), individual, total weekly time spent >7 MET threshold was 113 (65-330) minutes, whereas such time spent >10 MET threshold was 53 (9-115) minutes. Total time>7 MET threshold was 2.3% of monitor wear time. There were no differences in time above threshold between male and female participants (P=0.357) or among those with different levels of activity restriction (P=0.769). CONCLUSIONS: Current recommended activity guidelines are frequently exceeded during routine free-living activities in young participants with inherited arrhythmia syndromes. Whether this indicates increased risk for these individuals or excessively restrictive guidelines remains to be determined.

A family genetic risk communication framework: guiding tool development in genetics health services.

Family communication of genetic risk information is a complex process. Currently, there are no evidence-based interventions to help genetics professionals facilitate the process of disclosure within families. This study was designed to create a framework to assist in the development of tools to support patients in communicating genetic risk information to family members. A systematic review identified the factors relevant in communicating genetic risk information in families. A guiding theory for the proposed framework was selected and populated with the factors identified from the review. The review identified 112 factors of relevance. The theory of planned behaviour was selected to guide framework development, organising the framework in terms of the patient's attitudes about disclosure, perceived pressure to disclose and perceived control over disclosure. Attitudes about disclosure are influenced by a desire to protect oneself or family members, and the patient's perceptions of relevance of the information for family members, responsibility to disclose, family members' rights to information and the usefulness of communicating. Perceived pressure to disclose information is shaped by genetic professionals, family members and society. Perceived control over disclosure is affected by family relationships/dynamics, personal communication skills, the ability of the patient and family to understand the information and coping skills of the patient and family member. The family genetic risk communication framework presents a concise synthesis of the evidence on family communication of genetic information; it may be useful in creating and evaluating tools to help genetic counsellors and patients with communication issues.

Factors associated with knowledge of and satisfaction with newborn screening education: a survey of mothers.

PURPOSE: Effective parental education about newborn blood-spot screening may facilitate prompt follow-up, reduce psychosocial harms, and promote trust in screening programs. However, little is known about the aspects of education delivery and content that are of most importance for fostering understanding and meeting parental expectations. We aimed to identify elements of newborn blood-spot screening education and their associations with mothers' knowledge and satisfaction levels. METHODS: We conducted a survey (by mail) of 1,712 mothers who were residing in Ontario, Canada, and whose infants had recently undergone newborn blood-spot screening. RESULTS: We received 750 completed questionnaires (response rate 47%). Factors associated with respondents' higher knowledge of newborn blood-spot screening were higher level of education (odds ratio = 2.79), English being spoken at home (odds ratio = 1.96), receiving an information sheet at the time of newborn blood-spot screening (odds ratio = 1.57), and receiving information about how to interpret the results (odds ratio = 2.65). Factors associated with being satisfied were: receiving information prenatally (odds ratio = 2.35), from a health-care professional (odds ratio = 4.54), or from an information sheet at the time of newborn blood-spot screening (odds ratio = 1.72); and receiving messages about the purpose of screening (odds ratio = 3.78), the communication process (odds ratio = 2.57), the interpretation of the results (odds ratio = 4.19), and sample-handling methods (odds ratio = 3.13). CONCLUSION: Promoting mothers' understanding and meeting their expectations with respect to education about newborn blood-spot screening may require greater engagement with prenatal providers. It also calls for a greater emphasis on communicating with mothers about how blood samples are handled and about the meaning of the test results.

Apparent transmission distortion of a pericentric chromosome one inversion in a large multi-generation pedigree.

Pericentric chromosome inversions are often associated with infertility, recurrent pregnancy loss, and an increased risk for offspring with congenital anomalies. We report on a chromosome 1 inversion between 1p36.21 and 1q42.13, one of the largest described familial pericentric inversions of chromosome 1. The inversion was ascertained following the birth of a female with multiple congenital anomalies due to a recombinant chromosome 1. The inversion was subsequently detected or inferred in 16 healthy individuals over five generations. Interestingly, with a ratio of 16 carriers to 6 noncarriers, there appears to be transmission distortion of the inverted chromosome 1 within the family. Although there is no reported difficulty conceiving in the family, the risk of miscarriage is higher than predicted at 34% (13/38). The recurrence risk of a recombinant chromosome also appears to be lower than expected based on the mode of ascertainment. This case contributes to the spectrum of clinical features of chromosome 1 recombinants and raises the question of whether or not there is a selective advantage of the inverted chromosome at meiosis, conception, or post-zygotically that has contributed to transmission distortion of the inverted chromosome.

Recommendations for the use of genetic testing in the clinical evaluation of inherited cardiac arrhythmias associated with sudden cardiac death: Canadian Cardiovascular Society/Canadian Heart Rhythm Society joint position paper.

The era of gene discovery and molecular medicine has had a significant impact on clinical practice. Knowledge of specific genetic findings causative for or associated with human disease may enhance diagnostic accuracy and influence treatment decisions. In cardiovascular disease, gene discovery for inherited arrhythmia syndromes has advanced most rapidly. The arrhythmia specialist is often confronted with the challenge of diagnosing and managing genetic arrhythmia syndromes. There is now a clear need for guidelines on the appropriate use of genetic testing for the most common genetic conditions associated with a risk of sudden cardiac death. This document represents the first ever published recommendations outlining the role of genetic testing in various clinical scenarios, the specific genes to be considered for testing, and the utility of test results in the management of patients and their families.

Peer Observed Interaction and Structured Evaluation (POISE): a Canadian experience with peer supervision for genetic counselors.

Peer observation, while often used in other professions, has not been formally applied in genetic counseling. The objective of this study was to pilot a method of peer evaluation whereby genetic counselors observed, and were observed by, each other during patient interaction. All of the available genetic counselors participated in both rounds of the pilot study (six in round one, seven in round two). The genetic counselors that observed the session used an observation room. Most participants reported learning a new skill. Sensitivity to, and comfort with, the feedback process improved. We conclude that Peer-Observed Interaction and Structured Evaluation (POISE) provides an opportunity to refresh counseling approaches and develop feedback skills without causing undue team discord. This new approach to peer supervision in genetic counselling offers a live observation approach for genetic counsellor supervision.