Genome-wide rare variant score associates with morphological subtypes of autism spectrum disorder.

Defining different genetic subtypes of autism spectrum disorder (ASD) can enable the prediction of developmental outcomes. Based on minor physical and major congenital anomalies, we categorize 325 Canadian children with ASD into dysmorphic and nondysmorphic subgroups. We develop a method for calculating a patient-level, genome-wide rare variant score (GRVS) from whole-genome sequencing (WGS) data. GRVS is a sum of the number of variants in morphology-associated coding and non-coding regions, weighted by their effect sizes. Probands with dysmorphic ASD have a significantly higher GRVS compared to those with nondysmorphic ASD (P = 0.03). Using the polygenic transmission disequilibrium test, we observe an over-transmission of ASD-associated common variants in nondysmorphic ASD probands (P = 2.9 × 10-3). These findings replicate using WGS data from 442 ASD probands with accompanying morphology data from the Simons Simplex Collection. Our results provide support for an alternative genomic classification of ASD subgroups using morphology data, which may inform intervention protocols.

Identification of a novel in-frame deletion in KCNQ4 (DFNA2A) and evidence of multiple phenocopies of unknown origin in a family with ADSNHL.

Autosomal dominant sensorineural hearing loss (ADSNHL) is extremely genetically heterogeneous, making it difficult to molecularly diagnose. We identified a multiplex (n=28 affected) family from the genetic isolate of Newfoundland, Canada with variable SNHL and used a targeted sequencing approach based on population-specific alleles in WFS1, TMPRSS3 and PCDH15; recurrent mutations in GJB2 and GJB6; and frequently mutated exons of KCNQ4, COCH and TECTA. We identified a novel, in-frame deletion (c.806_808delCCT: p.S269del) in the voltage-gated potassium channel KCNQ4 (DFNA2), which in silico modeling predicts to disrupt multimerization of KCNQ4 subunits. Surprisingly, 10/23 deaf relatives are non-carriers of p.S269del. Further molecular characterization of the DFNA2 locus in deletion carriers ruled out the possibility of a pathogenic mutation other than p.S269del at the DFNA2A/B locus and linkage analysis showed significant linkage to DFNA2 (maximum LOD=3.3). Further support of genetic heterogeneity in family 2071 was revealed by comparisons of audio profiles between p.S269del carriers and non-carriers suggesting additional and as yet unknown etiologies. We discuss the serious implications that genetic heterogeneity, in this case observed within a single family, has on molecular diagnostics and genetic counseling.

Electrocardiographic left ventricular hypertrophy in renal transplant recipients: prognostic value and impact of blood pressure and anemia.

Left ventricular hypertrophy (LVH) is an independent risk factor for death and cardiovascular disease in the general population and dialysis patients. However, the causes and consequences of LVH have not been well described in renal transplant recipients (RTR). A retrolective cohort study was conducted in 473 RTR who were alive and free of cardiac disease at 1 yr. LVH was defined using the Cornell electrocardiographic (EKG) criteria. A total of 416 patients had an interpretable first-year EKG (88%), and 284 had an interpretable fifth-year EKG (78% of 5-yr survivors). Baseline characteristics were similar in patients with and without EKG. Of 416 patients, 57 had LVH in the first year, whereas 38 of 284 patients had LVH in the fifth year, of which 18 cases were de novo. Baseline LVH was a risk factor for death (RR 1.9 [1.22, 3.22]) and congestive heart failure (CHF) (RR 2.27 [1.08, 4.81]) and was independent of other major prognostic variables. Persistent or de novo LVH in the fifth year predicted subsequent death (RR 2.15 [1.14,4.01]) and CHF (2.71 [1.17, 6.30]). Anemia and diastolic BP were independent risk factors for increasing Cornell voltage (a marker of LV mass) between first and fifth years. Systolic BP was the only predictor of de novo LVH at 5 yr. It seems that EKG LVH is a significant risk factor for death and CHF in RTR and that anemia and hypertension are risk factors for LV growth. Whether aggressive treatment of hypertension and anemia can improve outcomes merits further study.

Congestive heart failure in renal transplant recipients: risk factors, outcomes, and relationship with ischemic heart disease.

Cardiovascular disease (CVD) is the major cause of death in renal transplant recipients (RTR). Several cohort studies have examined CVD in RTR, but none have addressed the development of congestive heart failure (CHF). CHF would hypothetically be a frequent and prognostically important event in RTR. A retrolective cohort study was, therefore, conducted in two Canadian centers to describe the incidence, risk factors for, and interrelationships between de novo CHF, de novo ischemic heart disease (IHD), and mortality in 638 consecutive adult RTR who were free of cardiac disease at 1 yr posttransplant. Detailed clinic and hospital records were available for 99% of patients. Median follow-up was 7 yr (range, 1 to 28 yr). De novo CHF occurred as frequently as de novo IHD (1.26 versus 1.22 events/100 patient-years, respectively) and appeared to carry a similar prognosis (relative risk for death, 1.78 [confidence interval, 1.21 to 2.61] for CHF versus 1.50 [1.05 to 2.13] for IHD). The incidence of CHF was considerably higher than that in the Framingham cohort, whereas the incidence of IHD was not, suggesting that renal transplantation might correspond more to a state of "accelerated heart failure" than to "accelerated atherosclerosis." Age, diabetes, gender, BP, and anemia were identified as independent risk factors for de novo CHF, whereas age, diabetes, gender, BP, and rejection were independent risk factors for de novo IHD. Optimal strategies for treatment of BP and anemia in RTR will need to be determined in randomized controlled trials.