SPTLC2 variants are associated with early-onset ALS and FTD due to aberrant sphingolipid synthesis

OBJECTIVE

Amyotrophic lateral sclerosis (ALS) is a devastating, incurable neurodegenerative disease. A subset of ALS patients manifests with early-onset and complex clinical phenotypes. We aimed to elucidate the genetic basis of these cases to enhance our understanding of disease etiology and facilitate the development of targeted therapies.

METHODS

Our research commenced with an in-depth genetic and biochemical investigation of two specific families, each with a member diagnosed with early-onset ALS (onset age of <40 years). This involved whole-exome sequencing, trio analysis, protein structure analysis, and sphingolipid measurements. Subsequently, we expanded our analysis to 62 probands with early-onset ALS and further included 440 patients with adult-onset ALS and 1163 healthy controls to assess the prevalence of identified genetic variants.

RESULTS

We identified heterozygous variants in the serine palmitoyltransferase long chain base subunit 2 (SPTLC2) gene in patients with early-onset ALS. These variants, located in a region closely adjacent to ORMDL3, bear similarities to SPTLC1 variants previously implicated in early-onset ALS. Patients with ALS carrying these SPTLC2 variants displayed elevated plasma ceramide levels, indicative of increased serine palmitoyltransferase (SPT) activity leading to sphingolipid overproduction.

INTERPRETATION

Our study revealed novel SPTLC2 variants in patients with early-onset ALS exhibiting frontotemporal dementia. The combination of genetic evidence and the observed elevation in plasma ceramide levels establishes a crucial link between dysregulated sphingolipid metabolism and ALS pathogenesis. These findings expand our understanding of ALS's genetic diversity and highlight the distinct roles of gene defects within SPT subunits in its development.

Early-onset acute kidney injury is a poor prognostic sign for allogeneic SCT recipients

Acute kidney injury (AKI) following stem-cell transplantation (SCT) contributes to a poor prognosis, yet its impact may vary depending on the timing of AKI onset. A prospective cohort study was performed to understand the significance of the onset timing in 103 allogeneic SCT (allo-SCT) recipients. AKI prior to stem-cell engraftment was defined as early AKI and subsequently occurring AKI as late AKI. Propensity score (PS) for early AKI was calculated using a logistic regression model to reduce confounding effects related to differences in clinical background between the early and late AKI groups. The cumulative incidences of early and late AKI were 22.3% and 54.9%, respectively. Non-relapse mortality (NRM) was 39.1% and 7.0%, and overall survival (OS) was 56.5% and 90.9% in early and late AKI at 100 days after AKI, respectively (P<0.001). The cumulative incidence of chronic kidney disease (CKD) over 2 years after SCT was 41.5% and 19.1% in early and late AKI, respectively (P=0.048). Logistic regression analysis adjusted for the PS showed that early AKI was significantly associated with OS (odds ratio (95% confidence interval); 4.63 (1.15-21.4), P=0.031) but with neither NRM (1.25 (0.28-5.33), P=0.766) nor CKD (1.85 (0.41-8.60), P=0.422). In conclusion, early AKI may portend a poor survival for allo-SCT recipients.

[Patient perceptions and satisfaction of psychiatric services at their discharge]

We conducted a multi-central survey on patient's perception and satisfaction of 31 psychiatric services at their discharge. The subjects were 364 patients who agreed to participate in the survey among 471 discharged patients between August 10th and September 10th, 1997. We excluded 48 patients emergently transferred to another hospitals, 47 patients with dementia or mental retardation, and 12 patients who refused to participate. Of the subjects, 326 patients (89.6%) responded. The rates of patients who rated the psychiatric care positively ranged between 79.4% (Amenity) and 93.6% (Overall satisfaction). Older patients tended to be more satisfied with psychiatric care than younger patients. Patients with schizophrenia and mood disorders rated the psychiatric care more positively, whereas patients with personality disorders rated negatively. Patients with neurosis rated the care positively in informed consent, but negatively in other items. Patients with the 60's score in Global Assessment of Functioning Scale rated higher in nurses and clerks than patients with other scores. Patients who have received their care in non-voluntary admission rated significantly lower in informed consent than other patients. There were no significant correlation of patient satisfaction with former admission and type of ward. Our results indicate that patient satisfaction survey could contribute to improve psychiatric care regarding patient characteristics in Japan.

Characteristics of nonresponders to a patient satisfaction survey at discharge from psychiatric hospitals

The study compared the demographic and clinical characteristics of patients treated in the 31 psychiatric hospitals in Japan who did and did not return a satisfaction survey at discharge. Of the 471 patients discharged in a one-month period, 364 agreed to participate. A total of 235 turned in completed forms, 91 turned in incomplete forms, and 38 did not return the form. The latter two groups were defined as nonresponders. Nonresponders were significantly older than responders, but no significant differences were found between the two groups in diagnosis and other demographic characteristics. Responders and incomplete responders had significantly higher scores on the Global Assessment of Functioning scale than those who did not return the survey.