Human inherited PD-L1 deficiency is clinically and immunologically less severe than PD-1 deficiency.

We previously reported two siblings with inherited PD-1 deficiency who died from autoimmune pneumonitis at 3 and 11 years of age after developing other autoimmune manifestations, including type 1 diabetes (T1D). We report here two siblings, aged 10 and 11 years, with neonatal-onset T1D (diagnosed at the ages of 1 day and 7 wk), who are homozygous for a splice-site variant of CD274 (encoding PD-L1). This variant results in the exclusive expression of an alternative, loss-of-function PD-L1 protein isoform in overexpression experiments and in the patients' primary leukocytes. Surprisingly, cytometric immunophenotyping and single-cell RNA sequencing analysis on blood leukocytes showed largely normal development and transcriptional profiles across lymphoid and myeloid subsets in the PD-L1-deficient siblings, contrasting with the extensive dysregulation of both lymphoid and myeloid leukocyte compartments in PD-1 deficiency. Our findings suggest that PD-1 and PD-L1 are essential for preventing early-onset T1D but that, unlike PD-1 deficiency, PD-L1 deficiency does not lead to fatal autoimmunity with extensive leukocytic dysregulation.

Glycemic Outcome Associated With Insulin Pump and Glucose Sensor Use in Children and Adolescents With Type 1 Diabetes. Data From the International Pediatric Registry SWEET.

OBJECTIVE: Insulin delivery methods, glucose-monitoring modalities, and related outcomes were examined in a large, international, diverse cohort of children and adolescents with type 1 diabetes from the Better Control in Pediatric and Adolescent Diabetes: Working to Create Centers of Reference (SWEET) -Registry. RESEARCH DESIGN AND METHODS: Participants with type 1 diabetes of ≥1 year, aged ≤18 years, and who had documented pump or sensor usage during the period August 2017-July 2019 were stratified into four categories: injections-no sensor (referent); injections + sensor; pump-no sensor; and pump + sensor. HbA1c and proportion of patients with diabetic ketoacidosis (DKA) or severe hypoglycemia (SH) were analyzed; linear and logistic regression models adjusted for demographics, region, and gross domestic product per capita were applied. RESULTS: Data of 25,654 participants were analyzed. The proportions of participants (adjusted HbA1c data) by study group were as follows: injections-no sensor group, 37.44% (8.72; 95% CI 8.68-8.75); injections + sensor group, 14.98% (8.30; 95% CI 8.25-8.35); pump-no sensor group, 17.22% (8.07; 95% CI 8.03-8.12); and pump + sensor group, 30.35% (7.81; 95% CI 7.77-7.84). HbA1c was lower in all categories of participants who used a pump and/or sensor compared with the injections-no sensor treatment method (P < 0.001). The proportion of DKA episodes was lower in participants in the pump + sensor (1.98%; 95% CI 1.64-2.48; P < 0.001) and the pump-no sensor (2.02%; 95% CI 1.64-2.48; P < 0.05) groups when compared with those in the injections-no sensor group (2.91%; 95% CI 2.59-3.31). The proportion of participants experiencing SH was lower in pump-no sensor group (1.10%; 95% CI 0.85-1.43; P < 0.001) but higher in the injections + sensor group (4.25%; 95% CI 3.65-4.95; P < 0.001) compared with the injections-no sensor group (2.35%; 95% CI 2.04-2.71). CONCLUSIONS: Lower HbA1c and fewer DKA episodes were observed in participants using either a pump or continuous glucose monitoring (CGM) or both. Pump use was associated with a lower rate of SH. Across SWEET centers, use of pumps and CGM is increasing. The concomitant use of pump and CGM was associated with an additive benefit.

Recessively Inherited LRBA Mutations Cause Autoimmunity Presenting as Neonatal Diabetes.

Young-onset autoimmune diabetes associated with additional autoimmunity usually reflects a polygenic predisposition, but rare cases result from monogenic autoimmunity. Diagnosing monogenic autoimmunity is crucial for patients' prognosis and clinical management. We sought to identify novel genetic causes of autoimmunity presenting with neonatal diabetes (NDM) (diagnosis <6 months). We performed exome sequencing in a patient with NDM and autoimmune lymphoproliferative syndrome and his unrelated, unaffected parents and identified compound heterozygous null mutations in LRBA Biallelic LRBA mutations cause common variable immunodeficiency-8; however, NDM has not been confirmed in this disorder. We sequenced LRBA in 169 additional patients with diabetes diagnosed <1 year without mutations in the 24 known NDM genes. We identified recessive null mutations in 8 additional probands, of which, 3 had NDM (<6 months). Diabetes was the presenting feature in 6 of 9 probands. Six of 17 (35%) patients born to consanguineous parents and with additional early-onset autoimmunity had recessive LRBA mutations. LRBA testing should be considered in patients with diabetes diagnosed <12 months, particularly if they have additional autoimmunity or are born to consanguineous parents. A genetic diagnosis is important as it can enable personalized therapy with abatacept, a CTLA-4 mimetic, and inform genetic counseling.