The mitochondrial rhomboid protease PSARL is a new candidate gene for type 2 diabetes

AIMS/HYPOTHESIS

This study aimed to identify genes that are expressed in skeletal muscle, encode proteins with functional significance in mitochondria, and are associated with type 2 diabetes.

METHODS

We screened for differentially expressed genes in skeletal muscle of Psammomys obesus (Israeli sand rats), and prioritised these on the basis of genomic localisation and bioinformatics analysis for proteins with likely mitochondrial functions.

RESULTS

We identified a mitochondrial intramembrane protease, known as presenilins-associated rhomboid-like protein (PSARL) that is associated with insulin resistance and type 2 diabetes. Expression of PSARL was reduced in skeletal muscle of diabetic Psammomys obesus, and restored after exercise training to successfully treat the diabetes. PSARL gene expression in human skeletal muscle was correlated with insulin sensitivity as assessed by glucose disposal during a hyperinsulinaemic-euglycaemic clamp. In 1,031 human subjects, an amino acid substitution (Leu262Val) in PSARL was associated with increased plasma insulin concentration, a key risk factor for diabetes. Furthermore, this variant interacted strongly with age to affect insulin levels, accounting for 5% of the variation in plasma insulin in elderly subjects.

CONCLUSIONS/INTERPRETATION

Variation in PSARL sequence and/or expression may be an important new risk factor for type 2 diabetes and other components of the metabolic syndrome.

Children with heart transplants: Lessons learned from 774 visits at a primary community clinic

Aims Unexpected decompensation of PHTRs may surprise, when the patient is at home. If the PHTR lives a distance from transplant center, the task of identifying risk factors of allograft rejection/dysfunction falls primarily on the PCP in the PCC, whether or not they are knowledgeable toward pediatric heart-transplantation. Methods We reviewed the medical reports of three heart-transplanted children in our periphery clinic between the years 2005 and 2019. Results The unexpected death of one patient, hours after he left our health facility, was the impetus for writing this article. Another heart transplant child attended our periphery clinic for 774 visits. Majority of visits were casual, others were scheduled, and the rest were for administrative affairs. We referred the PHTR to the transplantation center in 9% of all visits. In remaining 91% visits, we handled problems locally. Conclusions One of the important lessons we have learned through handling the PHTR at the PCC is that, during daily workflows and dealing with the occasional visits of a heart transplant child, related critical clinical information to allograft rejection or its dysfunction can easily evade from awareness of the attending physician. Through this study, we demonstrated that a program of summoning the PHTR to "initiated monthly visits" at the PCC enables the PCP to be maximally aware of critical clinical information, in addition to limiting futile referrals of 91% of the visits to specialized centers, without adversely affecting the prognosis.