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.

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.

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.

Discrepant DNA analysis in three patients with inherited arrhythmia: molecular genetic test results deserve a second glance.

Molecular results provide a basis for diagnosis, risk assessment, medical management and genetic counseling. Unlike other areas of laboratory medicine, molecular genetic tests are rarely repeated. We describe three patients with suspected inherited arrhythmia in whom genetic testing was arranged via clinical and/or research laboratories. In all three instances, initial test results appeared falsely negative, with no deleterious mutations detected by various methodologies in selected long-QT or catecholaminergic polymorphic ventricular tachycardia-related genes. Discordant results emerged upon repeat analysis in separate laboratories. The cases highlight the importance of clinical judgment and assessment of genetic test results and methodology, in addition to the role of re-testing in molecular genetic medicine, particularly in the case of uninformative negative results.

Molecular autopsy in the sudden cardiac death of a young woman: a first Canadian report.

Standard autopsy of young victims with sudden cardiac death commonly does not identify a specific pathological diagnosis. In such cases, sudden cardiac death may be secondary to a genetic condition predisposing the patient to ventricular arrhythmias. Failure to identify a genetic etiology for an unexpected sudden death may leave surviving family members at risk for a similar tragedy. The case of a 21-year-old woman who died suddenly while at rest is presented. Molecular genetic analysis of tissue retrieved from the regional coroner's office identified a novel missense mutation in the KCNH2 gene, a gene known to cause the long QT syndrome.

Spondylocarpotarsal synostosis with epiphyseal dysplasia.

We report on an 11-year-old boy with thoracolumbar fusion, carpal synostosis, short stature, scoliosis, lordosis, defective dentition, and recurrent otitis media consistent with the diagnosis of spondylocarpotarsal synostosis syndrome. Unlike other documented cases, radiographs of our patient at 5(1/2) years of age show delay in ossification of many of the epiphyses in addition to delay in carpal ossification. Such delay may have contributed to the distinctly short stature of this boy. This report both confirms and extends the phenotype of this recently delineated syndrome.