Rapid Genome Sequencing Diagnosis in Pediatric Patients with Liver Dysfunction

OBJECTIVE

To describe the usefulness of rapid whole genome sequencing (rWGS) in a cohort of children presenting with acute liver dysfunction.

STUDY DESIGN

This was a retrospective, population-based cohort study conducted at Primary Children's Hospital in Salt Lake City, Utah. Children meeting criteria for acute liver dysfunction who received rWGS between August 2019 and December 2021 were included. rWGS was performed on blood samples from the patient and parents (1 or both depending on availability). The clinical characteristics of patients with positive rWGS results were compared with those with negative results.

RESULTS

Eighteen patients with pediatric acute liver dysfunction who had rWGS were identified. The median turnaround time from the date rWGS testing was ordered to the date an initial report was received was 8 days with a shorter turnaround time in patients with a diagnostic rWGS (4 days vs 10 days; P = .03). A diagnostic result was identified in 7 of 18 patients (39%). Subsequently, 4 patients in this cohort, who had negative rWGS results, were found to have a toxic exposure accounting for their liver dysfunction. With removal of these patients, the diagnostic rate of rWGS was 7 of 14 (50%). The use of rWGS led to a change in management for 6 of 18 patients (33%).

CONCLUSIONS

We found that rWGS provided a diagnosis in up to 50% of pediatric acute liver dysfunction. rWGS allows for higher diagnostic rates in an expedited fashion that affects clinical management. These data support the routine use of rWGS for life-threatening disorders in children, specifically acute liver dysfunction.

Dicentric chromosome breakage in Drosophila melanogaster is influenced by pericentric heterochromatin and occurs in nonconserved hotspots

Chromosome breakage plays an important role in the evolution of karyotypes and can produce deleterious effects within a single individual, such as aneuploidy or cancer. Forces that influence how and where chromosomes break are not fully understood. In humans, breakage tends to occur in conserved hotspots called common fragile sites (CFS), especially during replication stress. By following the fate of dicentric chromosomes in Drosophila melanogaster, we find that breakage under tension also tends to occur in specific hotspots. Our experimental approach was to induce sister chromatid exchange in a ring chromosome to generate a dicentric chromosome with a double chromatid bridge. In the following cell division, the dicentric bridges may break. We analyzed the breakage patterns of 3 different ring-X chromosomes. These chromosomes differ by the amount and quality of heterochromatin they carry as well as their genealogical history. For all 3 chromosomes, breakage occurs preferentially in several hotspots. Surprisingly, we found that the hotspot locations are not conserved between the 3 chromosomes: each displays a unique array of breakage hotspots. The lack of hotspot conservation, along with a lack of response to aphidicolin, suggests that these breakage sites are not entirely analogous to CFS and may reveal new mechanisms of chromosome fragility. Additionally, the frequency of dicentric breakage and the durability of each chromosome's spindle attachment vary significantly between the 3 chromosomes and are correlated with the origin of the centromere and the amount of pericentric heterochromatin. We suggest that different centromere strengths could account for this.