Michele O’Connell

Disorders of sex development: Insights from targeted gene sequencing of a large international patient cohort

BackgroundDisorders of sex development (DSD) are congenital conditions in which chromosomal, gonadal, or phenotypic sex is atypical. Clinical management of DSD is often difficult and currently only 13% of patients receive an accurate clinical genetic diagnosis. To address this we have developed a massively parallel sequencing targeted DSD gene panel which allows us to sequence all 64 known diagnostic DSD genes and candidate genes simultaneously.ResultsWe analyzed DNA from the largest reported international cohort of patients with DSD (278 patients with 46,XY DSD and 48 with 46,XX DSD). Our targeted gene panel compares favorably with other sequencing platforms. We found a total of 28 diagnostic genes that are implicated in DSD, highlighting the genetic spectrum of this disorder. Sequencing revealed 93 previously unreported DSD gene variants. Overall, we identified a likely genetic diagnosis in 43% of patients with 46,XY DSD. In patients with 46,XY disorders of androgen synthesis and action the genetic diagnosis rate reached 60%. Surprisingly, little difference in diagnostic rate was observed between singletons and trios. In many cases our findings are informative as to the likely cause of the DSD, which will facilitate clinical management.ConclusionsOur massively parallel sequencing targeted DSD gene panel represents an economical means of improving the genetic diagnostic capability for patients affected by DSD. Implementation of this panel in a large cohort of patients has expanded our understanding of the underlying genetic etiology of DSD. The inclusion of research candidate genes also provides an invaluable resource for future identification of novel genes.

Major increase in Type 1 diabetes: no support for the Accelerator Hypothesis.

Background  The Accelerator Hypothesis postulates that the apparent increase in incidence of Type 1 diabetes mellitus (T1DM) is related to an acceleration of disease onset by weight‐related insulin resistance. Our diabetes clinic has experienced a major recent increase in newly diagnosed diabetes. The Accelerator Hypothesis predicts that this increase should be associated with younger age and increased body mass at diagnosis, with youngest children having the highest body mass index (BMI).

Insulin-dose-adjusted HbA1c-defined partial remission phase in a paediatric population—when is the honeymoon over?

There has been a resurgence of interest in the partial remission ‘honeymoon’ phase of Type 1 diabetes as an opportunity for immunomodulation, with the hope that preservation of a functional mass of b-cells may be a future possibility [1]. However, there has been much uncertainty regarding how to accurately define this partial remission phase, with previous methods intrinsically flawed by the codependence of their variables, namely HbA1c and insulin dose kg 1 day 1 [2,3]. A new measure has been proposed, which, for the first time, coalesces therapy and outcome measure into a numerical definition, shown to correlate with a stimulated C-peptide response [4]. This is the insulin-doseadjusted HbA1c, and a value of 9 has been identified as representing a patient in partial remission when the following formula is used: insulin-dose-adjusted HbA1c = (IDAA1C) HbA1c (%) + 4 [insulin dose (U kg 1 24 h )]. For the first time in a clinical setting, we have examined this formula by defining the duration and associated factors of the partial remission phase in our patient population. We conducted a retrospective review of all newly diagnosed patients from January 2005 to January 2006 (n = 156), excluding patientswhodid not have 1diabetes-associated antibodies, orwhohadmissingdata in the first year after diagnosis (n = 13 and 45, respectively). One hundred and nine patients were included, with a mean age at diagnosis of 9.0 3.4 years (male 55%, female 45%). Using the insulin-dose-adjusted HbA1c to define partial remission, the results obtained (see Table 1) were in keeping with internationally reported data [3,5]. Median duration of partial remission was 8 months (range 3–26 months). When we compared the insulindose-adjusted HbA1c to a purely dose-defined partial remission (0.5 U kg 1 24 h ), the dose definition grossly overestimated the proportion entering partial remission (67 vs. 35%). Age at diagnosis did not have a strong correlation with durationof remission (r = 0.26); however, none of the patients diagnosed at younger than 3.5 years of age had a remission phase, as defined by insulin-dose-adjusted HbA1c (n = 11). Children of < 3.5 years of age were also more likely to have diabetic ketoacidosis of moderate/severe grade at diagnosis than older children (P = 0.004) and this group were less likely to enter a partial remission phase [odds ratio 0.73 (95% CI 0.24–2.2)].We conclude that the insulin-dose-adjustedHbA1c is a clinically practical tool and have now introduced a computer-based algorithm to our outpatient clinic to predict those patients in partial remission who will require a dose increase of insulin before the next review.Whether this results in a subsequent improved trajectory in HbA1c is under review.

Glucose Tolerance during Pulmonary Exacerbations in Children with Cystic Fibrosis

Background Patients with Cystic Fibrosis (CF) are relatively insulinopenic and are at risk of diabetes, especially during times of stress. There is a paucity of data in the literature describing glucose tolerance during CF pulmonary exacerbations. We hypothesised that glucose tolerance would be worse during pulmonary exacerbations in children with CF than during clinical stability. Methods Patients with CF, 10 years or older, admitted with a pulmonary exacerbation underwent an OGTT within 48 hours of admission. A repeat OGTT was performed 4 to 6 weeks post discharge when the patients were well. Results Nine patients completed the study. Four patients were found to have normal glucose tolerance, 3 with impaired and 2 with CF related diabetes during the exacerbation. Mean change in 2-hour glucose was 1.1 mmol (SD = 0.77). At the follow up OGTT, 8 of 9 (89%) remained within their respective glucose tolerance status groupings. Conclusion The findings of this study show that there is little difference in glucose tolerance during CF exacerbations compared to clinical stability in the majority of patients.

Performance of a predictive algorithm in sensor-augmented pump therapy in the prevention of hypoglycaemia

The Predictive Low Glucose Management (PLGM) system consists of a Medtronic Veo pump, Enlite sensor, MiniLink REAL-Time transmitter, Bluetooth-RF translator and a predictive algorithm operating from a Blackberry smartphone. The system suspended insulin delivery when the pre-set hypoglycaemic threshold of 4.4mmol/L was predicted to be reached in 30 minutes. The aim of this study was to determine the plasma glucose profile with the PLGM system when hypoglycaemia was induced by (a) moderate-intensity exercise, (b) subcutaneous insulin bolus and (c) increasing the overnight basal infusion rate in individuals with type 1 diabetes. The primary outcome was the plasma glucose nadir following each hypoglycaemic stimulus with and without PLGM. Participants performed 30-60 minutes of moderate-intensity exercise or were administered a subcutaneous insulin bolus following a glucose stabilisation period on basal continuous subcutaneous insulin infusion. In participants studied with increased overnight basal rates, hypoglycaemia was induced by increasing basal rates by 180%. They were randomised and studied on 2 separate days; with PLGM off and with PLGM on. On both days, participants were observed until plasma glucose dropped to 2.8mmol/L or were symptomatic.

Can integrated technology improve self-care behavior in youth with type 1 diabetes? A randomized crossover trial of automated pump function.

Background: Automated blood glucose (BG) and insulin pump systems allow wireless transmission of all BG readings to a user’s pump. This study aimed to assess whether use of such a system, as compared with a manual BG entry insulin pump, resulted in higher mean daily frequency of BGs recorded after 6 months. Methods: A 12-month randomized crossover trial, comprising 2 phases, was conducted. All participants used insulin pump devices with automated vs manual BG entry for 6 months each; order of system use was randomly assigned. Device interactions were assessed from pump and glucometer downloads. Results: Thirty-five participants were enrolled; 9 withdrew during the study. Use of the automated insulin pump system resulted in higher mean daily BG recorded over 6 months of use when compared to a manual BG entry system (5.8 ± 1.7 vs 5.0 ± 1.9; P = .02 [95% confidence interval, 0.14 to 1.58]). Bolus frequency was similar between groups. No HbA1c difference was observed between groups at 6 months (8.0% [64 mmol/l] ± 1.3 automated vs 7.7% [61 mmol/l] ± 0.9 manual; P = .38). Post hoc analysis demonstrated improved ΔHbA1c with automated system use in an adolescent subgroup with suboptimal baseline BG frequency (–0.9% vs + 0.5%; P = .003). Conclusions: Use of an automated glucometer/insulin pump resulted in higher number of BGs recorded over 6 months when compared to an insulin pump with manual BG entry. This may be especially beneficial for adolescent manual system users who enter <5 BGs per day into their pump.

6. Mechanisms of Acute Dysglycemic Brain Dysfunction in T1D (379-OR)

SamenvattingCentral nervous system deficits are well described in type 1 diabetes (T1D); however the brain regions most affected and the underlying neurobiological mechanisms remain unclear. This prospective study aimed to use functional MRI (fMRI) and a working memory task (WMT) to assess changes in brain function between euglycemia (5.0 ± 0.5mmol/l) and hypoglycemia (2.6 ± 0.5mmol/l) or hyperglycemia (18-20 ± 0.5 mmol/l) in youth aged 12-18 y with T1D. Exclusion criteria: HbA1c > 9.0%, IQ < 70, prior history of DKA, seizure, neurological disease or substance abuse.

Childhood glycaemic control has an enduring effect on the lifetime risk of microvascular complications in type 1 diabetes mellitus

The development of diabetes-related microvascular complications in type 1 diabetes (T1DM) is known to be related to glycaemic control, but the degree to which variations in HbA1c across the lifetime contributes to this risk is unknown. Our hypothesis was that individuals with poor control in childhood and subsequent improved control in adulthood would still have an increased risk of severe diabetes-related complications when compared with individuals who achieved good control throughout the lifecourse. This study aimed to investigate this premise in a cohort for whom serial lifetime glycaemic data are available. The study population comprised children diagnosed with T1DM 8.2% in childhood, ≤8.2% in adulthood), “Worsening” (≤8.2% in childhood, >8.2% in adulthood), “Poor” (>8.2% throughout lifecourse). A total of 503 (male=253) individuals were identified, diagnosed 1975-2010. At the time of follow up, mean (SD) age was 27.9 (6.2) years and median (IQR) duration of diabetes was 17.8 (12.2, 23.2) years. Severe complications were documented in 26 (5.2%) and were associated with mean HbA1c at age 16-30 years (<0.05) and intra-individual lifetime glycaemic variability expressed as HbA1cSD (p=0.02). The relative risk (95% confidence interval) of developing severe complications in the improving, worsening and poor groups was 14.9 (1.7-130.9, p=0.01, n=50), 12.5 (1.4-109.4, p <0.01, n=60) and 15.4 (2.1-114.8, p <0.01, n=206) respectively when compared to the optimal group (n=187). In conclusion, the overall rate of severe complications is low in this cohort despite the lifecourse poor glycaemic control demonstrated in 40.1%. Our findings demonstrate that poor glycaemic control in childhood has a lasting effect on the development of severe microvascular complications in adulthood.