Development of a diagnostic DNA chip to screen for 30 autosomal recessive disorders in the Hutterite population

Aetiologies of low alkaline phosphatase in a Canadian Paediatric Tertiary Care Centre

Objectives

Increasingly, laboratories flag low serum alkaline phosphatase (sALP) that are age-and sex-specific in paediatrics. The aim of this study was to report clinical manifestations of paediatric patients with age-and sex-specific low sALP, thereby increasing awareness of its potential aetiologies.

Methods

This retrospective Canadian tertiary care paediatric hospital study assessed all sALP of ambulatory patients aged less than 18 years from 2015 to 2017. The hospital used a Beckman Coulter AU assay to measure sALP and compared values to the Canadian age-and sex-specific reference intervals from CALIPER. All children who had at least one subnormal age-and sex-specific sALP were evaluated. A review of medical charts of included patients was performed and demographic characteristics, medical history and diagnosis were collected, and categorized under groups of medical disorders.

Results

Of 11,874 included patients, 1,001 patients (9.2%) had low sALP. Of those, 48% (485/1,001) had transient low sALP activity and 9.6% (96/1,001) had persistently low sALP. Prolonged immobilization and inflammatory bowel disease represented the main aetiologies for persistently low sALP. Interestingly, 13.5% (13/96) of patients with persistently low sALP had no apparent aetiology.

Conclusions

Our results report aetiologies of low sALP in a Canadian paediatric population using age-and sex-specific Canadian reference ranges. This study highlights that healthcare providers should be aware that a low sALP may have clinical significance and should be repeated if warranted based on further clinical assessment.

Prevalence rates study of selected isolated non-Mendelian congenital anomalies in the Hutterite population of Alberta, 1980-2016

A study of the prevalence rates for selected isolated non-Mendelian congenital anomalies in the Hutterite Brethren of Alberta, Canada was undertaken to further examine longitudinal data in this isolated community that was last reported in 1985 (Lowry et al., 1985), although there are numerous publications on recessive disorders (Boycott et al., 2008; Triggs-Raine et al., 2016). Cases were ascertained from the Alberta Congenital Anomaly Surveillance System for the years 1997-2016. Since our initial results showed some surprising findings in the Hutterite Brethren, such as zero cases of spina bifida, cleft lip and palate, gastroschisis, and omphalocele, and a significant excess of cases with hypospadias, we extended the study to prior years (1980-1996) for selected anomalies. For the extended study period (1980-2016), there was a significant increased prevalence of hypospadias, tetralogy of Fallot and tricuspid atresia in the Hutterite population, and although not statistically significant, zero cases of cleft lip with cleft palate, gastroschisis and omphalocele were confirmed. Further research is needed to determine the precise effects of rural environmental exposures, lifestyle factors, and genetic associations for selected multifactorial congenital anomalies.

Diphthamide affects selenoprotein expression: Diphthamide deficiency reduces selenocysteine incorporation, decreases selenite sensitivity and pre-disposes to oxidative stress

The diphthamide modification of translation elongation factor 2 is highly conserved in eukaryotes and archaebacteria. Nevertheless, cells lacking diphthamide can carry out protein synthesis and are viable. We have analyzed the phenotypes of diphthamide deficient cells and found that diphthamide deficiency reduces selenocysteine incorporation into selenoproteins. Additional phenotypes resulting from diphthamide deficiency include altered tRNA-synthetase and selenoprotein transcript levels, hypersensitivity to oxidative stress and increased selenite tolerance. Diphthamide-eEF2 occupies the aminoacyl-tRNA translocation site at which UGA either stalls translation or decodes selenocysteine. Its position is in close proximity and mutually exclusive to the ribosomal binding site of release/recycling factor ABCE1, which harbors a redox-sensitive Fe-S cluster and, like diphthamide, is present in eukaryotes and archaea but not in eubacteria. Involvement of diphthamide in UGA-SECIS decoding may explain deregulated selenoprotein expression and as a consequence oxidative stress, NFkB activation and selenite tolerance in diphthamide deficient cells.