Increased referrals for congenital hyperinsulinism genetic testing in children with trisomy 21 reflects the high burden of non-genetic risk factors in this group.

BACKGROUND: Hyperinsulinism results from inappropriate insulin secretion during hypoglycaemia. Down syndrome is causally linked to a number of endocrine disorders including Type 1 diabetes and neonatal diabetes. We noted a high number of individuals with Down syndrome referred for hyperinsulinism genetic testing, and therefore aimed to investigate whether the prevalence of Down syndrome was increased in our hyperinsulinism cohort compared to the population. METHODS: We identified individuals with Down syndrome referred for hyperinsulinism genetic testing to the Exeter Genomics Laboratory between 2008 and 2020. We sequenced the known hyperinsulinism genes in all individuals and investigated their clinical features. RESULTS: We identified 11 individuals with Down syndrome in a cohort of 2011 patients referred for genetic testing for hyperinsulinism. This represents an increased prevalence compared to the population (2.5/2011 expected vs. 11/2011 observed, p = 6.8 × 10-5 ). A pathogenic ABCC8 mutation was identified in one of the 11 individuals. Of the remaining 10 individuals, five had non-genetic risk factors for hyperinsulinism resulting from the Down syndrome phenotype: intrauterine growth restriction, prematurity, gastric/oesophageal surgery, and asparaginase treatment for leukaemia. For five individuals no risk factors for hypoglycaemia were reported although two of these individuals had transient hyperinsulinism and one was lost to follow-up. CONCLUSIONS: Down syndrome is more common in patients with hyperinsulinism than in the population. This is likely due to an increased burden of non-genetic risk factors resulting from the Down syndrome phenotype. Down syndrome should not preclude genetic testing as coincidental monogenic hyperinsulinism and Down syndrome is possible.

DNA Polymerase Epsilon Deficiency Causes IMAGe Syndrome with Variable Immunodeficiency.

During genome replication, polymerase epsilon (Pol ε) acts as the major leading-strand DNA polymerase. Here we report the identification of biallelic mutations in POLE, encoding the Pol ε catalytic subunit POLE1, in 15 individuals from 12 families. Phenotypically, these individuals had clinical features closely resembling IMAGe syndrome (intrauterine growth restriction [IUGR], metaphyseal dysplasia, adrenal hypoplasia congenita, and genitourinary anomalies in males), a disorder previously associated with gain-of-function mutations in CDKN1C. POLE1-deficient individuals also exhibited distinctive facial features and variable immune dysfunction with evidence of lymphocyte deficiency. All subjects shared the same intronic variant (c.1686+32C>G) as part of a common haplotype, in combination with different loss-of-function variants in trans. The intronic variant alters splicing, and together the biallelic mutations lead to cellular deficiency of Pol ε and delayed S-phase progression. In summary, we establish POLE as a second gene in which mutations cause IMAGe syndrome. These findings add to a growing list of disorders due to mutations in DNA replication genes that manifest growth restriction alongside adrenal dysfunction and/or immunodeficiency, consolidating these as replisome phenotypes and highlighting a need for future studies to understand the tissue-specific development roles of the encoded proteins.

Optimal Timing of Repeat Newborn Screening for Congenital Hypothyroidism in Preterm Infants to Detect Delayed Thyroid-Stimulating Hormone Elevation.

OBJECTIVES: To evaluate the timing of a delayed rise in thyroid-stimulating hormone (TSH) levels in preterm infants with congenital hypothyroidism, and to determine whether cases of congenital hypothyroidism would be missed by using current consensus guidelines of repeat screening at approximately 2 weeks of age or 2 weeks after the first screening. STUDY DESIGN: The study was performed over a 13-year period (January 2004-December 2016). Whole-blood TSH samples were collected between 72 and 120 hours after birth. Repeat samples were collected weekly in preterm infants until the infant was term-corrected (37 weeks' gestation). Patients were followed up to determine whether congenital hypothyroidism was permanent or transient. RESULTS: Twenty-seven (50.9%) preterm infants born at <33 weeks of gestation who were diagnosed with congenital hypothyroidism had delayed TSH elevation and would not have been detected on first newborn screen. Twelve of these infants (40.7%) with delayed TSH elevation had decompensated hypothyroidism at diagnosis (free thyroxine [FT4] <10 pmol/L), and 4 had severe congenital hypothyroidism (FT4 <5.5 pmol/L) at diagnosis. If screening had been repeated only at 2 weeks of life, 13 infants (48%) with delayed TSH elevation would not have been identified. Of the 27 infants with delayed TSH elevation, 6 (22%) have permanent congenital hypothyroidism, and another 12 will be reevaluated at age 3 years. CONCLUSION: Repeat screening for congenital hypothyroidism in preterm infants is necessary to avoid missing cases of congenital hypothyroidism with delayed TSH elevation. Repeat screening once at 2 weeks of life will miss infants with delayed TSH elevation and decompensated permanent congenital hypothyroidism.

Catalogue of inherited disorders found among the Irish Traveller population.

Background Irish Travellers are an endogamous, nomadic, ethnic minority population mostly resident on the island of Ireland with smaller populations in Europe and the USA. High levels of consanguinity result in many rare autosomal recessive disorders. Due to founder effects and endogamy, most recessive disorders are caused by specific homozygous mutations unique to this population. Key clinicians and scientists with experience in managing rare disorders seen in this population have developed a de facto advisory service on differential diagnoses to consider when faced with specific clinical scenarios. Objective(s) To catalogue all known inherited disorders found in the Irish Traveller population. Methods We performed detailed literature and database searches to identify relevant publications and the disease mutations of known genetic disorders found in Irish Travellers. Results We identified 104 genetic disorders: 90 inherited in an autosomal recessive manner; 13 autosomal dominant and one a recurring chromosomal duplication. Conclusion We have collated our experience of inherited disorders found in the Irish Traveller population to make it publically available through this publication to facilitate a targeted genetic approach to diagnostics in this ethnic group.

Outcomes of using flash glucose monitoring technology by children and young people with type 1 diabetes in a single arm study.

BACKGROUND AND OBJECTIVE: Outcomes of using flash glucose monitoring have been reported in adults. This trial evaluated use in children and teenagers with type 1 diabetes. METHODS: Prospective, single arm, non-inferiority multicenter study to demonstrate equivalence of time in range (TIR [70-180 mg/dL]) by comparing 14-day masked sensor wear (baseline) with self-monitored blood glucose (SMBG) testing to the final 14-days of 8-week open-label system use for diabetes self-management including insulin dosing. RESULTS: A total of 76 children and teenagers (46.1% male; age 10.3 ± 4.0 years, type 1 diabetes duration 5.4 ± 3.7 years; mean ± SD) from 10 sites participated. TIR improved significantly by 0.9 ± 2.8 h/d (P = 0.005) vs SMBG baseline. Time in hyperglycemia (>180 mg/dL) reduced by -1.2 ± 3.3 h/d (P = 0.004). HbA1c reduced by -0.4% (-4.4 mmol/mol), from 7.9 ± 1.0% (62.9 ± 11.2 mmol/mol) baseline to 7.5 ± 0.9% (58.5 ± 9.8 mmol/mol) study end (P < 0.0001) with reductions across all age-subgroups (4-6, 7-12 and 13-17 years). Time in hypoglycemia (<70 mg/dL) was unaffected. Throughout the treatment phase system utilization was 91% ± 9; sensor scanning was 12.9 ± 5.7/d with SMBG dropping to 1.6 ± 1.9 from 7.7 ± 2.5/d. Diabetes Treatment Satisfaction Questionnaire "Total Treatment Satisfaction" score improved for parents (P < 0.0001) and teenagers (P < 0.0001). No adverse events (n = 121) were associated with sensor accuracy, 42 participants experienced sensor insertion signs and symptoms. Three participants experienced three mild device-related (sensor wear) symptoms, resolving quickly (without treatment [n = 2], non-prescription antihistamines [n = 1]). CONCLUSIONS: Children with diabetes improved glycemic control safely and effectively with short-term flash glucose monitoring compared to use of SMBG in a single arm study.

Bicoronal and metopic craniosynostosis in association with a de novo unbalanced t(2;7) chromosomal translocation.

We report the case of a developmentally appropriate infant male with a de novo unbalanced chromosome translocation involving bands 2q32.1 and 7p21.3. The child was noted to have metopic and bicoronal craniosynostosis with closely spaced eyes, turricephaly, and flattening of the forehead. © 2016 Wiley Periodicals, Inc.

Expanding the clinical spectrum of chromosome 15q26 terminal deletions associated with IGF-1 resistance.

Haploinsufficiency of the insulin-like growth factor-1 receptor (IGF1R) gene on chromosome 15q26.3 is associated with impaired prenatal and postnatal growth, developmental delay, dysmorphic features and skeletal abnormalities. Terminal deletions of chromosome 15q26 arising more proximally may also be associated with congenital heart disease, epilepsy, diaphragmatic hernia and renal anomalies. We report three additional cases of 15q26 terminal deletions with novel features which may further expand the spectrum of this rarely reported contiguous gene syndrome. Phenotypic features including neonatal lymphedema, aplasia cutis congenita and aortic root dilatation have not been reported previously. Similarly, laboratory features of insulin-like growth factor 1 (IGF-1) resistance are described, including markedly elevated IGF-1 of up to +4.7 SDS. In one patient, the elevated IGF-1 declined over time and this coincided with a period of spontaneous growth acceleration. CONCLUSION: Deletions of 15q26 are a potential risk factor for aortic root dilatation, neonatal lymphedema and aplasia cutis in addition to causing growth restriction. What is Known: • Terminal deletions of chromosome 15q26 are associated with impaired prenatal and postnatal growth, developmental delay, dysmorphic features and skeletal abnormalities. What is New: • Neonatal lymphedema, aplasia cutis congenita and aortic root dilatation have not been previously described in 15q26 terminal deletions and may represent novel features. • IGF-1 levels may be increased up to 4.7 SDS.

Next-generation sequencing reveals deep intronic cryptic ABCC8 and HADH splicing founder mutations causing hyperinsulinism by pseudoexon activation.

Next-generation sequencing (NGS) enables analysis of the human genome on a scale previously unachievable by Sanger sequencing. Exome sequencing of the coding regions and conserved splice sites has been very successful in the identification of disease-causing mutations, and targeting of these regions has extended clinical diagnostic testing from analysis of fewer than ten genes per phenotype to more than 100. Noncoding mutations have been less extensively studied despite evidence from mRNA analysis for the existence of deep intronic mutations in >20 genes. We investigated individuals with hyperinsulinaemic hypoglycaemia and biochemical or genetic evidence to suggest noncoding mutations by using NGS to analyze the entire genomic regions of ABCC8 (117 kb) and HADH (94 kb) from overlapping ~10 kb PCR amplicons. Two deep intronic mutations, c.1333-1013A>G in ABCC8 and c.636+471G>T HADH, were identified. Both are predicted to create a cryptic splice donor site and an out-of-frame pseudoexon. Sequence analysis of mRNA from affected individuals' fibroblasts or lymphoblastoid cells confirmed mutant transcripts with pseudoexon inclusion and premature termination codons. Testing of additional individuals showed that these are founder mutations in the Irish and Turkish populations, accounting for 14% of focal hyperinsulinism cases and 32% of subjects with HADH mutations in our cohort. The identification of deep intronic mutations has previously focused on the detection of aberrant mRNA transcripts in a subset of disorders for which RNA is readily obtained from the target tissue or ectopically expressed at sufficient levels. Our approach of using NGS to analyze the entire genomic DNA sequence is applicable to any disease.

The Association of Vitamin D Status with Acute Respiratory Morbidity in Preterm Infants.

OBJECTIVE: To assess the association between serum 25-hydroxyvitamin D (25OHD) levels and outcomes in preterm infants (<32 weeks gestation). STUDY DESIGN: Serum 25OHD was measured in mothers and their infants within 24 hours of birth, before the start of enteral vitamin D supplementation, and at discharge from the neonatal intensive care unit. We evaluated the associations between vitamin D status and various early preterm outcomes. RESULTS: Ninety-four preterm infants and their mothers were included; 92% of the infants had a 25OHD level≤50 nmol/L (20 ng/mL), and 64% had a 25OHD level<30 nmol/L (12 ng/mL). A low 25OHD level (<30 nmol/L) in preterm infants at birth was associated with increased oxygen requirement (P=.008), increased duration of intermittent positive-pressure ventilation during resuscitation at delivery (P=.032), and greater need for assisted ventilation (P=.013). CONCLUSION: We observed a high prevalence of low 25OHD (<30 nmol/L), and found an association between vitamin D status and acute respiratory morbidity in preterm infants after birth.

Inadequate vitamin D levels are associated with culture positive sepsis and poor outcomes in paediatric intensive care.

AIM: This study aimed to assess vitamin D status, and its determinants, in paediatric patients with suspected sepsis who were admitted to a paediatric intensive care unit (PICU). We also investigated the association between vitamin D status and clinical outcomes. METHODS: Serum 25-hydroxy vitamin D (25OHD) and clinical determinants were prospectively assessed in children with suspected sepsis (<12 years old) admitted to the PICU. The relationship between 25OHD and clinical outcomes was evaluated. Vitamin D status was also assessed in control children of a similar age. RESULTS: We enrolled 120 children with suspected sepsis admitted to the PICU and 30 paediatric controls. 25OHD was <50 nmol/L in 59% of the children admitted to the PICU and 25OHD was lower than in the controls (47 ± 29 vs 66 ± 26 nmol/L, p < 0.001). After adjusting for potential confounders, 25OHD was strongly associated with culture positive sepsis (p < 0.001), the paediatric index of mortality (p = 0.026) and the duration of mechanical ventilation (p = 0.008). There was a negative correlation between 25OHD and C-reactive protein (CRP): each 0.1% decrease in 25OHD increased CRP (p = 0.04). CONCLUSION: Children admitted to the PICU with suspected sepsis had lower 25OHD than controls and inadequate 25OHD status was associated with confirmed sepsis and poor outcomes.

A realist synthesis of multicentre comparative audit implementation: exploring what works and in which healthcare contexts.

BACKGROUND: Multicentre comparative clinical audits have the potential to improve patient care, allow benchmarking and inform resource allocation. However, implementing effective and sustainable large-scale audit can be difficult within busy and resource-constrained contemporary healthcare settings. There are little data on what facilitates the successful implementation of multicentre audits. As healthcare environments are complex sociocultural organisational environments, implementing multicentre audits within them is likely to be highly context dependent. OBJECTIVE: We aimed to examine factors that were influential in the implementation process of multicentre comparative audits within healthcare contexts-what worked, why, how and for whom? METHODS: A realist review was conducted in accordance with the Realist and Meta-narrative Evidence Syntheses: Evolving Standards reporting standards. A preliminary programme theory informed two systematic literature searches of peer-reviewed and grey literature. The main context-mechanism-outcome (CMO) configurations underlying the implementation processes of multicentre audits were identified and formed a final programme theory. RESULTS: 69 original articles were included in the realist synthesis. Four discrete CMO configurations were deduced from this synthesis, which together made up the final programme theory. These were: (1) generating trustworthy data; (2) encouraging audit participation; (3) ensuring audit sustainability; and (4) facilitating audit cycle completion. CONCLUSIONS: This study elucidated contexts, mechanisms and outcomes influential to the implementation processes of multicentre or national comparative audits in healthcare. The relevance of these contextual factors and generative mechanisms were supported by established theories of behaviour and findings from previous empirical research. These findings highlight the importance of balancing reliability with pragmatism within complex adaptive systems, generating and protecting human capital, ensuring fair and credible leadership and prioritising change facilitation.

International Newborn Screening Practices for the Early Detection of Congenital Adrenal Hyperplasia.

INTRODUCTION: Newborn screening (NBS) programmes vary internationally in their approach to screening. Guidelines for congenital adrenal hyperplasia (CAH) screening recommend the use of two-tier testing and gestational age cutoffs to minimise false-positive results. The aims of this study were to describe (1) the approaches; (2) protocols used; and (3) available outcomes for CAH screening internationally. METHODS: All members of the International Society for Neonatal Screening were asked to describe their CAH NBS protocols, with an emphasis on the use of second-tier testing, 17-hydroxyprogesterone (17OHP) cutoffs, and gestational age and birth weight adjustments. If available, screening outcomes were requested. RESULTS: Representatives from 23 screening programmes provided data. Most (n = 14; 61%) recommend sampling at 48-72 h of life. Fourteen (61%) use single-tier testing and 9 have a two-tier testing protocol. Gestational age cutoffs are used in 10 programmes, birth weight cutoffs in 3, and a combination of both in 9. One programme does not use either method of adjusting 17OHP cutoffs. Case definition of a positive test and the response to a positive test differed between programmes. CONCLUSIONS: We have demonstrated significant variation across all aspects of NBS for CAH, including timing, the use of single versus two-tier testing and cutoff interpretation. Collaboration between international screening programmes and implementation of new techniques to improve screen efficacy will facilitate ongoing expansion and quality improvement in CAH NBS.

Chromosome 20p11.2 deletions cause congenital hyperinsulinism via the loss of FOXA2 or its regulatory elements.

Persistent congenital hyperinsulinism (HI) is a rare genetically heterogeneous condition characterised by dysregulated insulin secretion leading to life-threatening hypoglycaemia. For up to 50% of affected individuals screening of the known HI genes does not identify a disease-causing variant. Large deletions have previously been used to identify novel regulatory regions causing HI. Here, we used genome sequencing to search for novel large (>1 Mb) deletions in 180 probands with HI of unknown cause and replicated our findings in a large cohort of 883 genetically unsolved individuals with HI using off-target copy number variant calling from targeted gene panels. We identified overlapping heterozygous deletions in five individuals (range 3-8 Mb) spanning chromosome 20p11.2. The pancreatic beta-cell transcription factor gene, FOXA2, a known cause of HI was deleted in two of the five individuals. In the remaining three, we found a minimal deleted region of 2.4 Mb adjacent to FOXA2 that encompasses multiple non-coding regulatory elements that are in conformational contact with FOXA2. Our data suggests that the deletions in these three children may cause disease through the dysregulation of FOXA2 expression. These findings provide new insights into the regulation of FOXA2 in the beta-cell and confirm an aetiological role for chromosome 20p11.2 deletions in syndromic HI.

Lack of sensitivity of the 1-µg low-dose ACTH stimulation test in a paediatric population with suboptimal cortisol responses to insulin-induced hypoglycaemia.

CONTEXT: The insulin-tolerance test (ITT) is the gold standard for evaluation of the hypothalamic-pituitary-adrenal (HPA) axis. The low-dose ACTH stimulation test is increasingly used for evaluation of secondary adrenal insufficiency as several studies performed in adults have demonstrated high sensitivity and specificity when compared to the ITT. Whether the ACTH stimulation test demonstrates similar sensitivity in a paediatric and adolescent population compared with the gold standard is unclear. OBJECTIVE: To compare the sensitivity of the low-dose (1-µg) Synacthen(™) test (LDSST) and the gold-standard ITT in a paediatric and adolescent population. DESIGN AND PATIENTS: A retrospective review of 42 consecutive LDSSTs in children and adolescents with suboptimal cortisol responses (peak <500 nm) on ITT. RESULTS: Thirty-one patients (74%) had an adequate cortisol response to low-dose Synacthen(™) (sensitivity 26%). Patients had a higher cortisol increment with the LDSST than ITT (median Δ cortisol 294 vs 168 nm, P < 0.0001) and correspondingly a higher cortisol peak (median peak cortisol 572 vs 396 nm, P < 0.0001). Patients who had a suboptimal peak cortisol both on ITT and on LDSST had a lower baseline cortisol on ITT (median 178 vs 227 nm, P = 0.04). Peak cortisol on ITT was significantly higher in patients who had a subsequent normal LDSST than those that did not (median 417 vs 300 nm, P = 0.0005). CONCLUSIONS: The 1-µg LDSST lacks sensitivity in detection of secondary adrenal insufficiency in children when compared to the gold-standard ITT.

Vitamin D nutritional status in preterm infants and response to supplementation.

Little is known about vitamin D status in preterm infants and their response to supplementation. To investigate this, we assessed serum 25-hydroxyvitamin D (25OHD) levels using RIA in a consecutive sample of stable preterm very low birth weight (VLBW) infants (born ≤ 32 weeks gestation or birth weight ≤ 1·5 kg), and we explored associated factors. Serum 25OHD level was first assessed once infants were tolerating feeds (n 274). If this first 25OHD level was below 50 nmol/l (20 ng/ml), which is the level associated with covering requirements in terms of skeletal health in the majority, then we recommended prolonged augmented vitamin D intake ( ≥ 10 µg (400 IU) daily) from a combination of fortified feeds and vitamin supplements and follow-up re-assessment at approximately 6 weeks corrected age (n 148). The first assessment, conducted at a median for chronological age of 18 (interquartile range (IQR) 11-28) d, found that 78 % had serum 25OHD levels below 50 nmol/l. Multivariable analysis demonstrated that the determinants of serum 25OHD levels were duration of vitamin D supplementation and gestational age at birth (r 2 0·215; P< 0·001). At follow-up, after a median of 104 (IQR 78-127) d, 87 % achieved levels ≥ 50 nmol/l and 8 % had levels >125 nmol/l, a level associated with potential risk of harm. We conclude that low 25OHD levels are an issue for preterm VLBW infants, warranting early nutritional intervention. In infants with serum 25OHD levels < 50 nmol/l, a vitamin D intake of ≥ 10 µg (400 IU) daily achieves target levels in the majority; however, further work is needed to determine the exact dose to safely meet target levels without overcorrection.

Adolescent perspectives on negotiating self-management responsibilities for type 1 diabetes with their parents.

OBJECTIVE: The overall purpose of this study was to explore adolescent perspectives on communicating about self-management of type 1 diabetes (T1D) and negotiating responsibilities for self-management with parents. METHODS: Semi-structured interviews were conducted with 28 adolescents aged 11-17 years living with T1D. Interviews were audio-recorded, transcribed verbatim and thematically analysed. RESULTS: Two themes and five subthemes were identified. The first theme, 'changing levels of involvement in self-management' describes the division of responsibility for self-management within the family and adolescents collaborating and sharing responsibilities with parents for self-management. The second theme, 'talking about self-management with parents' describes changes in patterns of parent-adolescent communication about T1D over time, adolescents' seeking parental feedback and advice and the factors that contribute to the promotion of self-management communication between adolescents and parents. CONCLUSION: This study identified that how adolescents perceive communication with their parents contributes to negotiation of responsibilities for self-management during adolescence. The findings provide a nuanced understanding of adolescent perspectives on communication with parents about T1D self-management and how parent-adolescent communication can be framed in ways that promote positive adolescent engagement with T1D self-management. PRACTICE IMPLICATIONS: Targeting parent-adolescent communication strategies may result in more optimal sharing of responsibilities and improved self-management.

Relationship between parent-adolescent communication and parent involvement in adolescent Type 1 diabetes management, parent/family wellbeing and glycaemic control.

OBJECTIVES: This study investigated the relationship between parent-reported degree of openness and extent of problems in parent-adolescent communication and parent involvement in adolescent Type 1 diabetes management, parent and family wellbeing and adolescent glycaemic control. METHODS: A cross-sectional quantitative survey was conducted. Parents completed measures of parent-adolescent communication, parent monitoring of diabetes care, diabetes family responsibility, parent knowledge of diabetes care, parent activation, parent diabetes distress, and diabetes family conflict. RESULTS: In total, 146 parents/guardians (121 mothers, mean age 46.56 years, SD 5.18) of adolescents aged 11-17 years (mean age 13.9 years, SD 1.81) with Type 1 diabetes completed the survey. Open parent-adolescent communication was significantly correlated to adolescents' voluntarily disclosing diabetes-specific information to their parents more frequently, increased parental knowledge of their adolescent's diabetes care completion, parents feeling more capable and willing to take action in relation to their adolescent's diabetes health, lower levels of diabetes-related parental distress, less diabetes-specific family conflict, and optimal glycaemic control. DISCUSSION: Parent-adolescent communication has an important role to play in Type 1 diabetes healthcare management and psychosocial wellbeing during adolescence. Optimising open parent-adolescent communication represents a potentially useful target for interventional research and should be considered by healthcare professionals during healthcare encounters.

Parents' perspectives of factors affecting parent-adolescent communication about type 1 diabetes and negotiation of self-management responsibilities.

Adolescence is an important time in which young people take on type 1 diabetes (T1D) self-management responsibility. Parents are key facilitators of this process. Little is known about parents' experiences of communicating with their children about T1D during adolescence. Semi-structured interviews were conducted with 32 parents (24 mothers and 8 fathers) of adolescents (11-17 years) living with T1D to explore how parents communicate about T1D and self-management with their adolescent children. Parents were recruited through two national child and adolescent diabetes and endocrine clinics and online advertisement through a national diabetes advocacy organisation. Interviews were transcribed verbatim and thematically analysed. Six themes were identified: parent factors, quality of the parent-adolescent relationship, communication strategies, adolescent factors, communication triggers and family/system factors. Understanding factors that impact communication about self-management between parents and adolescents will enable healthcare professionals to provide support and targeted interventions as parent and adolescent roles change over time.

Secondary Hyperparathyroidism in Children with Mucolipidosis Type II (I-Cell Disease): Irish Experience.

Mucolipidosis type II (ML II) is an autosomal recessive lysosomal targeting disorder that may present with features of hyperparathyroidism. The aim of this study was to describe in detail the clinical cases of ML II presenting to a tertiary referral centre with biochemical and/or radiological features of hyperparathyroidism. There were twenty-three children diagnosed with ML II in the Republic of Ireland from July 1998 to July 2021 inclusive (a 23-year period). The approximate incidence of ML II in the Republic of Ireland is, therefore, 1 per 64,000 live births. Medical records were available and were reviewed for 21 of the 23 children. Five of these had been identified as having biochemical and/or radiological features of hyperparathyroidism. Of these five, three children were born to Irish Traveller parents and two to non-Traveller Irish parents. All five children had radiological features of hyperparathyroidism (on skeletal survey), with evidence of antenatal fractures in three cases and an acute fracture in one. Four children had biochemical features of secondary hyperparathyroidism. Three children received treatment with high dose Vitamin D supplements and two who had antenatal/acute fractures were managed with minimal handling. We observed resolution of secondary hyperparathyroidism in all cases irrespective of treatment. Four of five children with ML II and hyperparathyroidism died as a result of cardiorespiratory failure at ages ranging from 10 months to 7 years. Biochemical and/or radiological evidence of hyperparathyroidism is commonly identified at presentation of ML II. Further studies are needed to establish the pathophysiology and optimal management of hyperparathyroidism in this cohort. Recognition of this association may improve diagnostic accuracy and management, facilitate family counseling and is also important for natural history data.

Clinical and genetic heterogeneity of HNF4A/HNF1A mutations in a multicentre paediatric cohort with hyperinsulinaemic hypoglycaemia.

OBJECTIVE: The phenotype mediated by HNF4A/HNF1A mutations is variable and includes diazoxide-responsive hyperinsulinaemic hypoglycaemia (HH) and maturity-onset diabetes of the young (MODY). DESIGN: We characterised an international multicentre paediatric cohort of patients with HNF4Aor HNF1Amutations presenting with HH over a 25-year period (1995-2020). METHODS: Clinical and genetic analysis data from five centres were obtained. Diazoxide responsiveness was defined as the ability to maintain normoglycaemia without intravenous glucose. Macrosomia was defined as a birth weight ≥90th centile. SPSS v.27.1 was used for data analysis. RESULTS: A total of 34 patients (70.6% female, n = 24) with a mean age of 7.1 years (s.d. 6.4) were included. A total of 21 different heterozygous HNF4Amutations were identified in 29 patients (four novels). Four different previously described heterozygous HNF1A mutations were detected in five patients. Most (97.1%, n = 33) developed hypoglycaemia by day 2 of life. The mean birth weight was 3.8 kg (s.d. 0.8), with most infants macrosomic (n = 21, 61.8%). Diazoxide was commenced in 28 patients (82.3%); all responded. HH resolved in 20 patients (58.8%) following a median of 0.9 years (interquartile range (IQR): 0.2-6.8). Nine patients (n = 9, 26.5%) had developmental delay. Two patients developed Fanconi syndrome (p.Arg63Trp, HNF4A) and four had other renal or hepatic findings. Five (14.7%) developed MODY at a median of 11.0 years (IQR: 9.0-13.9). Of patients with inherited mutations (n = 25, 73.5%), a family history of diabetes was present in 22 (88.0%). CONCLUSIONS: We build on the knowledge of the natural history and pancreatic and extra-pancreatic phenotypes of HNF4A/HNF1Amutations and illustrate the heterogeneity of this condition.