The Dutch founder mutation SDHD.D92Y shows a reduced penetrance for the development of paragangliomas in a large multigenerational family

Germline mutations in SDHD predispose to the development of head and neck paragangliomas, and phaeochromocytomas. The risk of developing a tumor depends on the sex of the parent who transmits the mutation: paragangliomas only arise upon paternal transmission. In this study, both the risk of paraganglioma and phaeochromocytoma formation, and the risk of developing associated symptoms were investigated in 243 family members with the SDHD.D92Y founder mutation. By using the Kaplan–Meier method, age-specific penetrance was calculated separately for paraganglioma formation as defined by magnetic resonance imaging (MRI) and for paraganglioma-related signs and symptoms. Evaluating clinical signs and symptoms alone, the penetrance reached a maximum of 57% by the age of 47 years. When MRI detection of occult paragangliomas was included, penetrance was estimated to be 54% by the age of 40 years, 68% by the age of 60 years and 87% by the age of 70 years. Multiple tumors were found in 65% and phaeochromocytomas were diagnosed in 8% of paraganglioma patients. Malignant paraganglioma was diagnosed in one patient (3%). Although the majority of carriers of a paternally inherited SDHD mutation will eventually develop head and neck paragangliomas, we find a lower penetrance than previous estimates from studies based on predominantly index cases. The family-based study described here emphasizes the importance of the identification and inclusion of clinically unaffected mutation carriers in all estimates of penetrance. This finding will allow a more accurate genetic counseling and warrants a ‘wait and scan'' policy for asymptomatic paragangliomas, combined with biochemical screening for catecholamine excess in SDHD-linked patients.     

Trends and cyclic variation in the incidence of childhood type 1 diabetes in two Italian regions over 33 years and during the COVID-19 pandemic

Aim

There is conflicting evidence about the impact of the COVID-19 pandemic on the incidence of type 1 diabetes. Here, we analysed long-term trends in the incidence of type 1 diabetes in Italian children and adolescents from 1989 to 2019 and compared the incidence observed during the COVID-19 pandemic with that estimated from long-term data.

Materials and Methods

This was a population-based incidence study using longitudinal data from two diabetes registries in mainland Italy. Trends in the incidence of type 1 diabetes from 1 January 1989 to 31 December 2019 were estimated using Poisson and segmented regression models.

Results

There was a significant increasing trend in the incidence of type 1 diabetes of 3.6% per year [95% confidence interval (CI): 2.4-4.8] between 1989 and 2003, a breakpoint in 2003, and then a constant incidence until 2019 (0.5%, 95% CI: -1.3 to 2.4). There was a significant 4-year cycle in incidence over the entire study period. The rate observed in 2021 (26.7, 95% CI: 23.0-30.9) was significantly higher than expected (19.5, 95% CI: 17.6-21.4; p = .010).

Conclusion

Long-term incidence analysis showed an unexpected increase in new cases of type 1 diabetes in 2021. The incidence of type 1 diabetes now needs continuous monitoring using population registries to understand better the impact of COVID-19 on new-onset type 1 diabetes in children.