Mode Of Ascertainment Research Articles

Province-Wide Ascertainment of Lynch Syndrome in Manitoba

Background & AimsWe describe the experience of Lynch Syndrome (LS) diagnosis in the province of Manitoba, Canada over the last twenty years. MethodsWe performed a retrospective review of charts from the provincial Genetics clinic from January 1, 2000-May 31, 2023. We extracted data on individuals identified to carry a germline pathogenic or likely pathogenic LS gene variant, the mode of ascertainment, family history, and cascade genetic testing (CGT). Data was stratified and compared pre and post the year of implementation (October 2013) of the provincial LS screening program (LSSP) and ascertainment by the LSSP versus clinic referrals (CR). ResultsBetween 2014-2021, 50/101 (49.5%) index cases were identified by the LSSP compared to 51/101 (50.5%) from CR. The proportion of PMS2 variants was 34% (17/50) for LSSP index cases compared to 21.6% (11/51) for CR 2014-2021 (p<0.001). Amongst CRs 2014-2021, 24/51 (47.1%) of families met the Amsterdam criteria, compared to 11/50 (22.0%) for the LSSP (p= 0.01). CGT occurred among 46.8% (95/203; average 1.9 relatives/index) of first-degree relatives (FDRs) of CR index cases versus 36.5% (84/230; average 1.7 relatives/index) of FDRs of LSSP index cases (p=0.03). Daughters were most likely to undergo CGT. ConclusionsA tumour screening program is more effective at detecting individuals with lower penetrant gene variants and families who do not meet traditional family history-based criteria. Cascade genetic testing is higher among clinic referrals compared to the screening program. These findings suggest a complementary role of these two ascertainment methods for Lynch syndrome.

Differences in genetic risk score profiles for drug use disorder, major depression, and ADHD as a function of sex, age at onset, recurrence, mode of ascertainment, and treatment.

Do genetic risk profiles for drug use disorder (DUD), major depression (MD), and attention-deficit hyperactivity disorder (ADHD) differ substantially as a function of sex, age at onset (AAO), recurrence, mode of ascertainment, and treatment? Family genetic risk scores (FGRS) for MD, anxiety disorders, bipolar disorder, schizophrenia, alcohol use disorder, DUD, ADHD, and autism-spectrum disorder were calculated from 1st-5th degree relatives in the Swedish population born 1932-1995 (n = 5 829 952). Profiles of these FGRS were obtained and compared across various subgroups of DUD, MD, and ADHD cases. Differences in FGRS profiles for DUD, MD, and ADHD by sex were modest, but they varied substantially by AAO, recurrence, ascertainment, and treatment with scores typically higher in cases with greater severity (e.g. early AAO, high recurrence, ascertainment in high intensity clinical settings, and treatment). However, severity was not always related to purer genetic profiles, as genetic risk for many disorders often increased together. However, some results, such as by mode of ascertainment from different Swedish registries, produced qualitative differences in FGRS profiles. Differences in FGRS profiles for DUD, MD, and ADHD varied substantially by AAO, recurrence, ascertainment, and treatment. Replication of psychiatric studies, particularly those examining genetic factors, may be difficult unless cases are matched not only by diagnosis but by important clinical characteristics. Genetic correlations between psychiatric disorders could arise through one disorder impacting on the patterns of ascertainment for the other, rather than from the direct effects of shared genetic liabilities.

The impact of sex, age at onset, recurrence, mode of ascertainment and medical complications on the family genetic risk score profiles for alcohol use disorder.

Alcohol use disorder (AUD) is clinically heterogeneous. We examine its potential genetic heterogeneity as a function of sex, age, clinical features and mode of ascertainment. In the Swedish population born 1932-1995 (n = 5 829 952), we examined the genetic risk profiles for AUD, major depression (MD), anxiety disorders, bipolar disorder, drug use disorder (DUD), attention deficit-hyperactivity disorder (ADHD) and criminal behavior (CB) in 361 124 cases of AUD subdivided by sex, age at onset (AAO), recurrence, mode of ascertainment and medical complications. Family genetic risk scores (FGRS), calculated from 1st to 5th-degree relatives controlling of cohabitation, assesses genetic risk from phenotypes in the family, not from DNA variants. FGRS profiles differed modestly across sex with all scores higher in females. Differences were more pronounced for AAO and recurrence with the FGRS for AUD, DUD, ADHD and CB substantially higher in cases with early AAO or high recurrence rates. Genetic profiles differed considerably by mode of ascertainment, with higher FGRS for AUD and most other disorders in patients seen in hospital v. primary care settings. Cases of AUD with medical complications had higher FGRS for AUD. AUD cases comorbid with MD and DUD had higher FGRS risk for AUD, but this genetic may be less specific given increases in FGRS for multiple other disorders. From a genetic perspective, AUD differs substantially as a function of AAO, recurrence, mode of ascertainment and patterns of comorbidity, suggesting caution in cross-sample comparisons of AUD cohorts that differ in these features.

Management of Latent Autoimmune Diabetes in Adults: A Consensus Statement From an International Expert Panel.

A substantial proportion of patients with adult-onset diabetes share features of both type 1 diabetes (T1D) and type 2 diabetes (T2D). These individuals, at diagnosis, clinically resemble T2D patients by not requiring insulin treatment, yet they have immunogenetic markers associated with T1D. Such a slowly evolving form of autoimmune diabetes, described as latent autoimmune diabetes of adults (LADA), accounts for 2–12% of all patients with adult-onset diabetes, though they show considerable variability according to their demographics and mode of ascertainment. While therapeutic strategies aim for metabolic control and preservation of residual insulin secretory capacity, endotype heterogeneity within LADA implies a personalized approach to treatment. Faced with a paucity of large-scale clinical trials in LADA, an expert panel reviewed data and delineated one therapeutic approach. Building on the 2020 American Diabetes Association (ADA)/European Association for the Study of Diabetes (EASD) consensus for T2D and heterogeneity within autoimmune diabetes, we propose “deviations” for LADA from those guidelines. Within LADA, C-peptide values, proxy for β-cell function, drive therapeutic decisions. Three broad categories of random C-peptide levels were introduced by the panel: 1) C-peptide levels <0.3 nmol/L: a multiple-insulin regimen recommended as for T1D; 2) C-peptide values ≥0.3 and ≤0.7 nmol/L: defined by the panel as a “gray area” in which a modified ADA/EASD algorithm for T2D is recommended; consider insulin in combination with other therapies to modulate β-cell failure and limit diabetic complications; 3) C-peptide values >0.7 nmol/L: suggests a modified ADA/EASD algorithm as for T2D but allowing for the potentially progressive nature of LADA by monitoring C-peptide to adjust treatment. The panel concluded by advising general screening for LADA in newly diagnosed non–insulin-requiring diabetes and, importantly, that large randomized clinical trials are warranted.

Obesity as an independent risk factor for group B streptococcal colonization

Objective: Approximately 25% of women are colonized with group B streptococcus (GBS). We assessed whether body mass index (BMI) is an independent risk factor for GBS colonization.Study design: We performed a retrospective cohort study using a previously collected database of women who delivered singleton gestations at term. Individual patient medical record review was undertaken to add GBS-related information to the database. Univariable logistic regression was used to assess the relationship between GBS colonization and BMI. Multivariable logistic regression was used to adjust for confounders.Results: A total of 2045 patients met enrollment criteria. The prevalence of GBS colonization was 29%. In the unadjusted analysis, there was a statistically significant increase in GBS colonization per unit increase in BMI (odds ratio [OR] 1.03, 95% confidence interval [CI] 1.01–1.04). This relationship remained significant after adjusting for confounders (race, marital status, payer, chronic hypertension, concomitant genital infections) (OR 1.01, 95% CI 1.00–1.03; p = 0.04). By BMI category, there were no differences in antibiotic susceptibilities or mode of ascertainment of GBS colonization.Conclusion: Obesity is an independent risk factor for GBS colonization; however, this association is weak.

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.

Jaw tremor: Prevalence and clinical correlates in three essential tremor case samples

The spectrum of involuntary movements seen in essential tremor (ET) is limited. Jaw tremor is one such movement. The prevalence and clinical correlates of jaw tremor have not been studied in detail. The objective of this study was to estimate the prevalence and examine the clinical correlates of jaw tremor in ET using ET cases from three distinct settings (population, tertiary-referral center, brain repository). All ET cases underwent a videotaped tremor examination in which tremors (including limb, head, voice, and jaw) were assessed. The prevalence [95% confidence interval (CI)] of jaw tremor was lowest in the population sample (7.5%; 3.9%-14.2%), intermediate in the tertiary-referral center (10.1%; 6.8%-14.7%), and highest in the brain repository (18.0%; 12.3%-25.5%; P = 0.03). Jaw tremor was associated with older age (P < 0.001), more severe action tremor of the arms (P < 0.001), and presence of head and voice tremor (P < 0.001). Jaw tremor was present in 4/14 (28.6%) ET cases with consistent rest tremor vs. 15/193 (7.8%) cases without rest tremor (odds ratio = 4.8; 95% CI = 1.3-7.0; P = 0.009). The prevalence of jaw tremor was 7.5% to 18.0% and was dependent on the mode of ascertainment, being least prevalent in a population-based sample. ET cases with jaw tremor had a more clinically severe and more topographically widespread disorder. The association in our study between jaw tremor and rest tremor, along with the published observation that jaw tremor can occur in Parkinson's disease (PD), raises the question whether jaw tremor in ET is a marker for subsequent conversion to PD.

Redefining the risks of prenatally ascertained supernumerary marker chromosomes: a collaborative study

Background: A marker chromosome is defined as a structurally abnormal chromosome that cannot be identified by routine cytogenetics. The risk for phenotypic abnormalities associated with a marker chromosome depends on...

Towards standardized measurement of adverse events in spine surgery: conceptual model and pilot evaluation

BackgroundIndependent of efficacy, information on safety of surgical procedures is essential for informed choices. We seek to develop standardized methodology for describing the safety of spinal operations and apply these methods to study lumbar surgery. We present a conceptual model for evaluating the safety of spine surgery and describe development of tools to measure principal components of this model: (1) specifying outcome by explicit criteria for adverse event definition, mode of ascertainment, cause, severity, or preventability, and (2) quantitatively measuring predictors such as patient factors, comorbidity, severity of degenerative spine disease, and invasiveness of spine surgery.MethodsWe created operational definitions for 176 adverse occurrences and established multiple mechanisms for reporting them. We developed new methods to quantify the severity of adverse occurrences, degeneration of lumbar spine, and invasiveness of spinal procedures. Using kappa statistics and intra-class correlation coefficients, we assessed agreement for the following: four reviewers independently coding etiology, preventability, and severity for 141 adverse occurrences, two observers coding lumbar spine degenerative changes in 10 selected cases, and two researchers coding invasiveness of surgery for 50 initial cases.ResultsDuring the first six months of prospective surveillance, rigorous daily medical record reviews identified 92.6% of the adverse occurrences we recorded, and voluntary reports by providers identified 38.5% (surgeons reported 18.3%, inpatient rounding team reported 23.1%, and conferences discussed 6.1%). Trained observers had fair agreement in classifying etiology of 141 adverse occurrences into 18 categories (kappa = 0.35), but agreement was substantial (kappa ≥ 0.61) for 4 specific categories: technical error, failure in communication, systems failure, and no error. Preventability assessment had moderate agreement (mean weighted kappa = 0.44). Adverse occurrence severity rating had fair agreement (mean weighted kappa = 0.33) when using a scale based on the JCAHO Sentinel Event Policy, but agreement was substantial for severity ratings on a new 11-point numerical severity scale (ICC = 0.74). There was excellent inter-rater agreement for a lumbar degenerative disease severity score (ICC = 0.98) and an index of surgery invasiveness (ICC = 0.99).ConclusionComposite measures of disease severity and surgery invasiveness may allow development of risk-adjusted predictive models for adverse events in spine surgery. Standard measures of adverse events and risk adjustment may also facilitate post-marketing surveillance of spinal devices, effectiveness research, and quality improvement.

Segregation analysis of IgE levels in 335 French families (EGEA) using different strategies to correct for the ascertainment through a correlated trait (asthma).

The main objective of this study was to search for a major gene controlling total serum immunoglobulin E (IgE) levels, an intermediate phenotype for asthma and allergy. We studied 335 French nuclear families of the EGEA study (Epidemiological study of the Genetics and Environment of Asthma), ascertained through asthmatic probands (123 are parents in the family, 212 children). Segregation analyses were performed by regressive models, which can take into account a major gene effect, various sources of familial covariation (genetic and/or environmental) as well as measured risk factors (i.e. , age, sex, smoking habits). Different strategies were considered to account for the mode of ascertainment of the families through a correlated trait (asthma): the ascertainment mode was either ignored (strategy A) or taken into account by adjusting IgE levels for the position in the family, i.e., probands, blood relatives, spouses (strategy B) or excluding the asthmatic children-probands and computing the likelihood of each family conditionally on parents' IgE levels (strategy C). Whereas a major gene effect could not be detected with strategy A, strategies B and C showed evidence for the transmission of a dominant major gene for high IgE levels, which was more significant with strategy B. This gene does not interact with any of the covariates and is responsible for approximately 15% of IgE variation (the allele frequency is 0.65).

Frequency of meiotic trisomy depends on involved chromosome and mode of ascertainment

Although maternal meiotic errors predominate in most studies of nonmosaic trisomy, studies of trisomy ascertained through confined placental mosaicism (CPM) have shown a high rate of somatic errors. However, origin of trisomy of many of the chromosomes involved in CPM has not been evaluated previously in cases ascertained through spontaneous abortions (SAs). Therefore, it was impossible to determine if the relative lack of meiotic errors in trisomy-CPM cases was a characteristic of the specific chromosome involved or due simply to ascertainment through a mosaic state. In the present study, parental and meiotic/somatic stages of origin of trisomy were determined in 89 SAs involving trisomy of chromosomes 2, 4 to 10, 12, 15, 17, and 20. Comparisons were then made to origin of trisomy in cases of confined and generalized trisomy mosaicism. Although somatic errors are generally more common in mosaic cases, this depends on the specific chromosome involved. The results suggest that there are chromosome-specific differences in the relative frequency of somatic chromosome gain or loss and/or the ability of an early somatic loss of one chromosome from a trisomic conceptus to “rescue” the pregnancy. As mean maternal age was less in the somatic than meiotic origin cases (P < 0.01), the age distribution of the study population should also influence the probability of detecting a somatic error. No phenotypic differences were apparent when cases were subdivided based on either parent or stage of origin of the trisomy. Am. J. Med. Genet. 84:34–42, 1999. © 1999 Wiley-Liss, Inc.

Frequency of meiotic trisomy depends on involved chromosome and mode of ascertainment

Although maternal meiotic errors predominate in most studies of nonmosaic trisomy, studies of trisomy ascertained through confined placental mosaicism (CPM) have shown a high rate of somatic errors. However, origin of trisomy of many of the chromosomes involved in CPM has not been evaluated previously in cases ascertained through spontaneous abortions (SAs). Therefore, it was impossible to determine if the relative lack of meiotic errors in trisomy-CPM cases was a characteristic of the specific chromosome involved or due simply to ascertainment through a mosaic state. In the present study, parental and meiotic/somatic stages of origin of trisomy were determined in 89 SAs involving trisomy of chromosomes 2, 4 to 10, 12, 15, 17, and 20. Comparisons were then made to origin of trisomy in cases of confined and generalized trisomy mosaicism. Although somatic errors are generally more common in mosaic cases, this depends on the specific chromosome involved. The results suggest that there are chromosome-specific differences in the relative frequency of somatic chromosome gain or loss and/or the ability of an early somatic loss of one chromosome from a trisomic conceptus to "rescue" the pregnancy. As mean maternal age was less in the somatic than meiotic origin cases (P < 0.01), the age distribution of the study population should also influence the probability of detecting a somatic error. No phenotypic differences were apparent when cases were subdivided based on either parent or stage of origin of the trisomy.

Systematic search for uniparental disomy in early fetal losses: The results and a review of the literature

About 20% of all human conceptuses are estimated to be trisomic and trisomy of all chromosomes remains a common cause of early fetal loss. Uniparental disomy (UPD) has been reported for most human chromosomes and may be an underrecognized contributor to embryonic lethality. To investigate the contribution of UPD to spontaneous abortions, we devised a genome-based screening strategy to identify holochromosomic UPD in 18 fetal losses. No cases of UPD were identified using this approach. Based on our data, UPD does not appear to be a significant contributor to early embryonic lethality. The results of the study are presented along with a review of the cases of UPD reported in the literature by chromosome, parental origin, mode of ascertainment, and phenotypic consequences due to imprinting.

Systematic search for uniparental disomy in early fetal losses: The results and a review of the literature

About 20% of all human conceptuses are estimated to be trisomic and trisomy of all chromosomes remains a common cause of early fetal loss. Uniparental disomy (UPD) has been reported for most human chromosomes and may be an underrecognized contributor to embryonic lethality. To investigate the contribution of UPD to spontaneous abortions, we devised a genome-based screening strategy to identify holochromosomic UPD in 18 fetal losses. No cases of UPD were identified using this approach. Based on our data, UPD does not appear to be a significant contributor to early embryonic lethality. The results of the study are presented along with a review of the cases of UPD reported in the literature by chromosome, parental origin, mode of ascertainment, and phenotypic consequences due to imprinting. Am. J. Med. Genet. 79:366–372, 1998. © 1998 Wiley-Liss, Inc.

Prenatal diagnosis of the skeletal dysplasias

We examined the accuracy of prenatal diagnosis of skeletal dysplasias and ways to refine this ability. A total of 226 fetuses and stillbirths referred for suspected skeletal dysplasia were evaluated. The fetal age, mode of ascertainment, and referring diagnosis were analyzed with regard to the final diagnosis. The leading mode of diagnosis was routine ultrasonography performed between 16 and 24 weeks' gestation. Twenty-two cases (9.7%) had previous sibs, parents, or cousins affected. The most common final diagnosis was osteogenesis imperfecta. In 15 cases (7%) the fetus did not appear to have a skeletal dysplasia or an obvious dysmorphic syndrome. Prenatal diagnosis of skeletal dysplasia can be made as early as 14 weeks. Most cases are sporadic. Fetal radiographs help in reaching an accurate diagnosis or at least in identifying the probable lethal disorders.

Logistic Regression for Clustered Binary Data in Proband Studies with Application to Familial Aggregation of Sleep Disorders

Estimation is considered for the class of conditional logistic regression models for clustered binary data proposed by Qu et al. (Communications in Statistics, Series A 16, 3447-3476, 1987) when clusters are sampled on the basis of the outcome for one or more cluster members. The problem is suggested by data from a study designed to investigate familial aggregation of sleep disorders. After appropriate consideration of the mode of ascertainment of "cases" and "controls," it is shown that the model is preserved under this form of sampling, and a method of estimation is presented. The inconsistency of two alternative methods is demonstrated, and an example is provided.

859 HISPANIC RECOMBINANT 8 (REC 8) SYNDROME: SEGREGATION ANALYSIS

Pericentric inversions have been reported for almost all human chromosomes. While some (e.g., inv 9) are benign, others represent a significant reproductive risk for recombinant offspring. Reported risks range from 1-10% depending upon the chromosome involved and the mode of ascertainment. Thirty-one probands representing 24 Hispanic kindreds have been documented to have rec(8)dup q secondary to a parental inv(8)(p23q22). The clinical phenotype associated with rec(8)dup q includes a characteristic facies, congenital heart disease, and developmental and postnatal growth retardation (Am. J. Med. Genet., 10:229, 1981). Detailed pedigree and cytogenetic data collected from the 24 kindreds (223 individuals from 67 sibships) was analyzed by segregation analysis. The risk for an inv(8) carrier parent was 7% for rec(8) offspring and 60% for inv(8) carrier offspring. The risk for SAB/stillbirth (11%) was not significantly increased above the general population. Only one of the two possible recombinants was identified in these kindreds. All kindreds have, to date, been of Hispanic background with origins in southern Colorado and northern New Mexico. The Hispanic background, geographic localization, and common ancestry in three kindreds suggest a single origin of the Hispanic inv(8).

The intellectually handicapped mother and her child.

Hockey, Athel, and Bain, Jill (1979). Aust. Paediatr. J., 15, 173–176. The intellectually handicapped mother and her child. This paper presents information on the intellectually handicapped mother with regard to numbers, mode of ascertainment, diagnosis, intelligence, number of children born, intelligence and outcome for the child. It assesses the role of genetic counselling and its limitations in this field. It defines the most appropriate form early intervention for the offspring to offset or prevent handicaps. Cases are used to illustrate and discuss the effect of assortive mating: the difficulty of defining risk to a person, herself affected, and of expecting a reasoned decision; joint plans to follow up and assist in the care of the children by Child Health Services and the Division for the Intellectually Handicapped.Reasons are given for the conclusion that an eugenic approach is inappropriate here. Instead, genetic counselling and family planning, with practical training in child rearing are the main resources.

A goodness‐of‐fit test for the polygenic threshold model: Application to pyloric stenosis

A new test of goodness of fit for the polygenic threshold model is proposed. This test, when applied to disorders showing different incidence rates in males and females, is designed to account for ascertainment in more detail than previously done by other investigators. This is accomplished by computing the expected distribution of nuclear families with more than one affected sib conditioned on several family-dependent variables, including whether each family was ascertained via only affected boys or via at least one affected girl. A direct measure of the probability of observing a data set is thereby derived. The test, when applied to data on pyloric stenosis, exposes the critical nature of the ascertainment procedures. Different levels of statistical significance are obtained when mode of ascertainment is taken into account than when the mode of ascertainment is ignored.

Epidemiology of Cornelia de Lange's syndrome.

A prevalence investigation of Cornelia de Lange's syndrome in Denmark is presented. The patients were traced by screening all institutional mentally retarded patients, patients in schools and kindergartens for imbecile patients and finally by getting information on Cornelia de Lange patients known to pediatric departments. In this way 24 patients, 10 men and 14 women, were found. This amounts to a population prevalence of 0.5/100 000. Clinical data, histories of the patients and genealogical data are presented by means of tables. The eldest patient was 49 years old, but 75% of the patients were younger than 20 years. Two of the probands were sibs. Another 2 sibs were registered as mentally retarded without specific syndromes. One case of consanguinity among parents was found. The mode of ascertainment is discussed and it is concluded that the present investigation presents a minimum prevalence figure. Four patients are presented who for various reasons were not available during the prevalence investigation proper. A prevalence figure of 0.6/100 000 is found if these 4 patients are included in the calculations. One of the last mentioned patients represented a familial case. The patient in question was a girl with a younger half-brother, the mother in common, both children being very typical cases of Cornella de Lange's syndrome.