Mobile element insertion detection in 89,874 clinical exomes.

PURPOSE: Exome sequencing (ES) is increasingly used for the diagnosis of rare genetic disease. However, some pathogenic sequence variants within the exome go undetected due to the technical difficulty of identifying them. Mobile element insertions (MEIs) are a known cause of genetic disease in humans but have been historically difficult to detect via ES and similar targeted sequencing methods. METHODS: We developed and applied a novel MEI detection method prospectively to samples received for clinical ES beginning in November 2017. Positive MEI findings were confirmed by an orthogonal method and reported back to the ordering provider. In this study, we examined 89,874 samples from 38,871 cases. RESULTS: Diagnostic MEIs were present in 0.03% (95% binomial test confidence interval: 0.02-0.06%) of all cases and account for 0.15% (95% binomial test confidence interval: 0.08-0.25%) of cases with a molecular diagnosis. One diagnostic MEI was a novel founder event. Most patients with pathogenic MEIs had prior genetic testing, three of whom had previous negative DNA sequencing analysis of the diagnostic gene. CONCLUSION: MEI detection from ES is a valuable diagnostic tool, reveals molecular findings that may be undetected by other sequencing assays, and increases diagnostic yield by 0.15%.

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.

Survey of the Definition of Fetal Viability and the Availability, Indications, and Decision Making Processes for Post-Viability Termination of Pregnancy for Fetal Abnormalities and Health Conditions in Canada.

The purpose of this study was to explore the definition of fetal viability and the availability, indications, and decision making processes for post-viability termination of pregnancy for fetal abnormalities and health conditions in Canada. An online survey of members of the Canadian Association of Genetic Counsellors, the Canadian College of Medical Geneticists, and the Canadian Society for Maternal-Fetal Medicine who provide direct counselling to, or management of, prenatal patients in Canada (total sample size 815). Results of this study showed that the majority of respondents indicated that their centre will offer post-viability termination of pregnancy (98/123; 80 %). Sixty-seven percent (68/101) of respondents reported the definition of fetal viability to be 24 weeks' gestation. Most respondents reported that a collaborative decision making process was used to determine if post-viability termination of pregnancy would be offered (136/170; 80 %). For conditions presumed to be lethal/likely lethal, the majority of respondents would "sometimes" or "always" offer post-viability termination of pregnancy, whereas for conditions presumed to have a mild effect, the majority of respondents would "rarely" or "never" offer post-viability termination of pregnancy. Ninety percent (77/86) of respondents reported that perinatal hospice is offered as an alternative to termination of pregnancy. In conclusion, this study suggests that although post-viability termination is available in many provinces in Canada, variation in the definition of fetal viability and indications appear to exist. While these variations may lead to unequal access to post-viability termination of pregnancy across Canada, they might also represent the complexity of the decision making process and the importance of examining individual factors to ensure that the most appropriate decision is made in each case.

First and second trimester maternal serum markers for prenatal aneuploidy screening: An update on the adjustment factors for race, smoking, and insulin dependent diabetes mellitus.

OBJECTIVES: The concentrations of maternal serum markers for aneuploidy screening are influenced by maternal characteristics such as race, smoking, insulin dependent diabetes mellitus (IDDM), and in vitro fertilization (IVF). Accurate risk estimation requires adjustment of initial values for these characteristics. This study aims to update and validate adjustment factors for race, smoking, and IDDM. METHODS: The study included singleton pregnancies that received multiple marker screening in Ontario, Canada between January 2012, and December 2018, and had their information collected in the Better Outcomes Registry & Network (BORN) Ontario. Serum markers assessed included first trimester pregnancy-associated plasma protein A (PAPP-A), free ß and total human chorionic gonadotropin (hCG), placental growth factor (PlGF) and αlpha-fetoprotein (AFP); second trimester AFP, unconjugated estriol (uE3), total hCG and inhibin A. The Mann-Whitney U test was used to assess the differences in the median multiple of the median (MoM) of serum markers between study and reference groups. New adjustment factors were generated by dividing the median MoM of a particular race, individuals who smoke tobacco, or have IDDM by those of the reference groups. RESULTS: The study included 624,789 pregnancies. There were statistically significant differences in serum marker concentrations among pregnant individuals who were Black, Asian, or First Nations compared to a White group, those who smoked compared to Non-smoking individuals, and those with IDDM compared to Non-IDDM group. New adjustment factors for race, smoking, and IDDM were validated by comparing median MoM of serum markers corrected using the current adjustment factors and new adjustment factors generated in this study. CONCLUSION: The adjustment factors generated in this study can adjust the effects of race, smoking, and IDDM on serum markers more accurately.

Survey of prenatal counselling practices regarding aneuploidy risk modification, invasive diagnostic procedure risks, and procedure eligibility criteria in Canadian centres.

OBJECTIVE: To explore prenatal practices related to aneuploidy screening, risk modification, and invasive diagnostic procedures across Canadian centres. METHODS: We conducted a survey of members of the Canadian Association of Genetic Counsellors, the Canadian College of Medical Genetics, and the Canadian Society of Maternal Fetal Medicine, who provide direct counselling or management of prenatal patients in Canada. RESULTS: Eighty-two of 157 respondents indicated that their centre's definition of advanced maternal age was ≥ 35 years, with 33/157 respondents reporting an advanced maternal age definition of ≥ 40 years. The majority of respondents reported that prenatal serum screening for aneuploidy is provincially funded in their province or territory (121/147). The majority of respondents who reported that prenatal screening is not provincially funded (17/147) were from Quebec (14/17). Thirty-nine of 123 respondents reported that their centre defines increased nuchal translucency as ≥ 3.0 mm, whereas 49/123 reported a definition of ≥ 3.5 mm. Sixty-four of 150 respondents reported that the aneuploidy risk provided by serum screening is modified by a soft marker likelihood ratio, whereas 46/150 respondents reported that both age-related and serum screening risks are modified. Fifty-nine of 124 respondents reported that their centre will modify aneuploidy risk after a normal ultrasound; the most commonly cited negative likelihood ratio was 0.5. The most commonly reported procedure-related risk for chorionic villus sampling was 1/100 (123/147) and for amniocentesis was 1/200 (73/142). CONCLUSION: This study demonstrates inconsistencies in prenatal practices and access to screening programs across Canada. The information gained from this study will inform policy advisors developing prenatal practice guidelines at both the provincial and national levels.

Expression of Heat Shock Protein 70 Is Insufficient To Extend Drosophila melanogaster Longevity.

It has been known for over 20 years that Drosophila melanogaster flies with twelve additional copies of the hsp70 gene encoding the 70 kD heat shock protein lives longer after a non-lethal heat treatment. Since the heat treatment also induces the expression of additional heat shock proteins, the biological effect can be due either to HSP70 acting alone or in combination. This study used the UAS/GAL4 system to determine whether hsp70 is sufficient to affect the longevity and the resistance to thermal, oxidative or desiccation stresses of the whole organism. We observed that HSP70 expression in the nervous system or muscles has no effect on longevity or stress resistance but ubiquitous expression reduces the life span of males. We also observed that the down-regulation of hsp70 using RNAi did not affect longevity.