WFS1 protein expression correlates with clinical progression of optic atrophy in patients with Wolfram syndrome.

BACKGROUND: Wolfram syndrome (WFS) is a rare disorder characterised by childhood-onset diabetes mellitus and progressive optic atrophy. Most patients have variants in the WFS1 gene. We undertook functional studies of WFS1 variants and correlated these with WFS1 protein expression and phenotype. METHODS: 9 patients with a clinical diagnosis of WFS were studied with quantitative PCR for markers of endoplasmic reticulum (ER) stress and immunoblotting of fibroblast protein extracts for WFS1 protein expression. Luciferase reporter assay was used to assess ATF-6 dependent unfolded protein response (UPR) activation. RESULTS: 6 patients with compound heterozygous nonsense mutations in WFS1 had no detectable WFS1 protein expression; 3 patients with missense variants had 4%, 45% and 48% WFS1 protein expression. One of these also had an OPA1 mutation and was reclassified as autosomal dominant optic atrophy-plus syndrome. There were no correlations between ER stress marker mRNA and WFS1 protein expression. ERSE-luciferase reporter indicated activation of the ATF6 branch of UPR in two patients tested. Patients with partial WFS1 expression showed milder visual acuity impairment (asymptomatic or colour blind only), compared with those with absent expression (registered severe vision impaired) (p=0.04). These differences remained after adjusting for duration of optic atrophy. CONCLUSIONS: Patients with WFS who have partial WFS1 protein expression present with milder visual impairment. This suggests a protective effect of partial WFS1 protein expression on the severity and perhaps progression of vision impairment and that therapies to increase residual WFS1 protein expression may be beneficial.

Factors affecting the support for physical activity in children and adolescents with type 1 diabetes mellitus: a national survey of health care professionals' perceptions.

BACKGROUND: Many children and adolescents with Type 1 Diabetes Mellitus (T1DM) don't meet the recommended levels of physical activity. Healthcare professionals (HCPs) have a key role in supporting and encouraging children and adolescents with T1DM to be physically active. This study aims to understand the perspectives of HCPs in relation to supporting physical activity and implementing guidelines relating to physical activity. METHODS: An online mixed methods survey was circulated to HCPs in pediatric diabetes units in England and Wales. Participants were asked about how they support physical activity in their clinic and their perceptions of barriers/enablers of providing physical activity support to children and adolescents with T1DM. Quantitative data were analysed descriptively. An deductive thematic approach was applied to the free text responses using the Capability Opportunity Motivation model of Behaviour (COM-B) as a framework. RESULTS: Responses were received from 114 individuals at 77 different pediatric diabetes units (45% of pediatric diabetes units in England and Wales). HCPs surveyed felt that the promotion of physical activity is important (90%) and advised patients to increase levels of physical activity (88%). 19% of the respondents felt they did not have sufficient knowledge to provide support. HCPs reported limited knowledge and confidence, time and resources as barriers to providing support. They also felt the current guidance was too complicated with few practical solutions. CONCLUSION: Pediatric HCPs need training and support to be able to encourage and support children and adolescents with T1D to be a physical activity. In addition, resources that provide simple and practical advice to manage glucose around exercise are needed.

ImprintSeq, a novel tool to interrogate DNA methylation at human imprinted regions and diagnose multilocus imprinting disturbance.

PURPOSE: Disruptions of genomic imprinting are associated with congenital imprinting disorders (CIDs) and other disease states, including cancer. CIDs are most often associated with altered methylation at imprinted differentially methylated regions (iDMRs). In some cases, multiple iDMRs are affected causing multilocus imprinting disturbances (MLIDs). The availability of accurate, quantitative, and scalable high-throughput methods to interrogate multiple iDMRs simultaneously would enhance clinical diagnostics and research. METHODS: We report the development of a custom targeted methylation sequencing panel that covered most relevant 63 iDMRs for CIDs and the detection of MLIDs. We tested it in 70 healthy controls and 147 individuals with CIDs. We distinguished loss and gain of methylation per differentially methylated region and classified high and moderate methylation alterations. RESULTS: Across a range of CIDs with a variety of molecular mechanisms, ImprintSeq performed at 98.4% sensitivity, 99.9% specificity, and 99.9% accuracy (when compared with previous diagnostic testing). ImprintSeq was highly sensitive for detecting MLIDs and enabled diagnostic criteria for MLID to be proposed. In a child with extreme MLID profile a probable genetic cause was identified. CONCLUSION: ImprintSeq provides a novel assay for clinical diagnostic and research studies of CIDs, MLIDs, and the role of disordered imprinting in human disease states.

An effective and cost-saving structured education program teaching dynamic glucose management strategies to a socio-economically deprived cohort with type 1 diabetes in a VIRTUAL setting.

OBJECTIVES: Compare the clinical and cost-effectiveness of an established face to face (F2F) structured education program to a new remote (VIRTUAL) program teaching dynamic glucose management (DynamicGM) to children and young people with type 1 diabetes (CYPD) using continuous glucose monitoring (CGM). To ascertain the most effective DynamicGM strategies predicting time in range (TIR) (3.9-10.0 mmol/L) and incorporating these into a user-friendly teaching aid. DESIGN AND METHODS: Effectiveness of the F2F and VIRTUAL programs were ascertained by comparing the mean change (Δ) from baseline to 6 months in HbA1c, TIR and severe hypoglycemia. Delivery cost for the two programs were evaluated. Factors predicting TIR in the combined cohort were determined and incorporated into a user-friendly infographic. RESULTS: First 50 graduates per group were evaluated. The mean difference in Δ HbA1c, Δ TIR and Δ episodes of severe hypoglycemia between VIRTUAL and F2F groups were 1.16 (p = 0.47), 0.76 (p = 0.78) and -0.06 (p = 0.61) respectively. Delivery cost per 50 CYPD for VIRTUAL and F2F were $5752 and $7020, respectively. The strongest predictors of TIR (n = 100) were short bursts of exercise (10-40 min) to lower hyperglycemia (p < 0.001), using trend arrow adjustment tools (p < 0.001) and adjusting pre-meal bolus timing based on trend arrows (p < 0.01). These strategies were translated into a GAME (Stop highs), SET (Stay in target), MATCH (Prevent lows) mnemonic. CONCLUSION: Teaching DynamicGM VIRTUALLY is just as effective as F2F delivery and cost saving. Short bursts of exercise and using CGM trend arrows to adjust insulin dose and timing improves TIR.

Comparison of the clinical scoring systems in Silver-Russell syndrome and development of modified diagnostic criteria to guide molecular genetic testing.

BACKGROUND: About half of all children with a clinical diagnosis of Silver-Russell syndrome (SRS) have a detectable molecular genetic abnormality (maternal uniparental disomy of chromosome upd(7)mat or hypomethylation of H19 differentially methylated region (DMR). The selection of children for molecular genetic testing can be difficult for non-specialists because of the broad phenotypic spectrum of SRS and the tendency of the facial features to mitigate during late childhood. Several clinical scoring systems for SRS have been developed by specialist researchers, but the utility of these for guiding molecular genetic testing in routine clinical practice has not been established. OBJECTIVES: To evaluate the utility of four published clinical scoring systems for genetic testing in a cohort of patients referred to a clinical service laboratory. PATIENTS: Individuals with suspected SRS referred for molecular genetic testing of H19 DMR methylation status or upd(7)mat. RESULTS: 36 of 139 (25.9%) patients referred for testing had a genetic abnormality identified. Comparison of four published clinical scoring systems demonstrated that all included subjective criteria that could be difficult for the general clinician to assess. We developed a novel, simplified, scoring system utilising four objective, easily measured parameters that performed similarly to the most sensitive and specific published scoring system. DISCUSSION: Effective utilisation of genetic testing by clinicians without specialist clinical genetics training will be facilitated by the development of targeted testing protocols that are based on robust objective clinical features and are designed for use in a busy clinical practice rather than a research setting.

Gonadal Failure in a Male With 3-M Syndrome.

OMIM 273750 (3-M) syndrome is a rare cause of severe short stature with variable dysmorphic features caused by pathogenic variants in several genes including cullin7 gene (CUL7). Hypogonadism and hypospadias have been described in only a few males. We report a patient with CUL7 pathogenic variant who had bifid scrotum and perineal hypospadias at birth. He entered puberty spontaneously at age 12 years and appropriately completed pubertal development by 15 years. Subsequently, a regression of testicular volumes, increased gonadotropin levels, and reduced (although normal) testosterone levels were observed. This case highlights the importance of careful pubertal monitoring as pubertal dysfunction may be associated with 3-M syndrome.

Enhancing equity in access to automated insulin delivery systems in an ethnically and socioeconomically diverse group of children with type 1 diabetes.

INTRODUCTION: Manufacturer-supported didactic teaching programmes offer effective automated insulin delivery (AID) systems onboarding in children and young people (CYP) with type 1 diabetes (T1D). However, this approach has limited flexibility to accommodate the needs of families requiring additional support. RESEARCH DESIGN AND METHODS: Evaluate the efficacy of an inperson manufacturer-supported didactic teaching programme (Group A), in comparison to a flexible flipped learning approach delivered virtually or inperson (Group B). Retrospective analysis of CYP with T1D using continuous glucose monitoring (CGM), who were initiated on AID systems between 2021 and 2023. Compare CGM metrics from baseline to 90 days for both groups A and B. Additionally, compare the two groups for change in CGM metrics over the 90-day period (∆), patient demographics and onboarding time. RESULTS: Group A consisted of 74 CYP (53% male) with median age of 13.9 years and Group B 91 CYP (54% male) with median age of 12.7 years. From baseline to 90 days, Group A lowered mean (±SD) time above range (TAR, >10.0 mmol/L) from 47.6% (±15.0) to 33.2% (±15.0) (p<0.001), increased time in range (TIR, 3.9-10.0 mmol/L) from 50.4% (±14.0) to 64.7% (±10.2) (p<0.001). From baseline to 90 days, Group B lowered TAR from 51.3% (±15.1) to 34.5% (±11.3) (p<0.001) and increased TIR from 46.5% (±14.5) to 63.7% (±11.0) (p<0.001). There was no difference from baseline to 90 days for time below range (TBR, <3.9 mmol/L) for Group A and Group B. ∆ TAR, TIR and TBR for both groups were comparable. Group B consisted of CYP with higher socioeconomic deprivation, greater ethnic diversity and lower carer education achievement (p<0.05). The majority of Group B (n=79, 87%) chose virtual flipped learning, halving diabetes educator time and increasing onboarding cadence by fivefold. CONCLUSIONS: A flexible virtual flipped learning programme increases onboarding cadence and capacity to offer equitable AID system onboarding.

Presentation and characteristics of children with screen-detected type 1 diabetes: learnings from the ELSA general population pediatric screening study.

INTRODUCTION: We describe the identification and management of general population screen-detected type 1 diabetes (T1D) and share learnings for best practice. RESEARCH DESIGN AND METHODS: Children diagnosed with T1D through a general population screening initiative, the EarLy Surveillance for Autoimmune diabetes (ELSA) study, were reviewed and described.Parents provided written, informed consent for inclusion in the case series. RESULTS: 14 children with insulin requiring (stage 3) T1D are described. These cases offer unique insights into the features of screen-detected T1D. T1D is identified sooner through screening programs, characterized by absent/short symptom duration, median presenting glycated hemoglobin 6.6% (49 mmol/mol) and insulin requirements<0.5 units/kg/day. ELSA identified four children at stage 3 and another 4 progressed within 4 months of ELSA completion, including two single seropositive children. Six children developed stage 3 T1D prior to ELSA completion, including two children (14%, n=2/14) with diabetic ketoacidosis prior to confirmed antibody status. CONCLUSIONS: There are three main learnings from this case series. First, T1D identified through screening is at an earlier stage of its natural history and requires personalized insulin regimens with lower total daily insulin doses. Second, single autoantibody seropositivity can rapidly progress to stage 3. Finally, insulin requirement can manifest at any stage of the T1D screening pathway, and therefore early education around symptom recognition is essential for families participating in screening programs.

Heterozygous CDC73 mutation causing hyperparathyroidism in children and adolescents: a report of 2 cases.

OBJECTIVES: Primary hyperparathyroidism (PHPT), whilst common in elderly populations, is rare in adolescents. Hereditary cases make up less than 10% of patients with PH. We report two patients with CDC73 mutation presenting in early adolescence. CASE PRESENTATION: Case 1: A 14-year-old patient was referred from an adolescent mental health unit with hypercalcaemia. Imaging revealed a parathyroid adenoma. Genetic testing of the patient showed a heterozygous deletion of CDC73. Case 2: A 10-year-old patient was admitted to the general paediatric ward with symptoms suggestive of hypercalcaemia. The patient was known to carry an autosomal dominant mutation of CDC73. Imaging of the parathyroid gland showed bilateral adenoma. CONCLUSIONS: We present two patients with CDC73 defects, who both presented with symptoms of hypercalcaemia. The cases highlight the difference in paediatric populations with PHPT who are often symptomatic at the time of diagnosis when compared to adult patients.

2022 European Thyroid Association Guidelines for the management of pediatric thyroid nodules and differentiated thyroid carcinoma.

At present, no European recommendations for the management of pediatric thyroid nodules and differentiated thyroid carcinoma (DTC) exist. Differences in clinical, molecular, and pathological characteristics between pediatric and adult DTC emphasize the need for specific recommendations for the pediatric population. An expert panel was instituted by the executive committee of the European Thyroid Association including an international community of experts from a variety of disciplines including pediatric and adult endocrinology, pathology, endocrine surgery, nuclear medicine, clinical genetics, and oncology. The 2015 American Thyroid Association Pediatric Guideline was used as framework for the present guideline. Areas of discordance were identified, and clinical questions were formulated. The expert panel members discussed the evidence and formulated recommendations based on the latest evidence and expert opinion. Children with a thyroid nodule or DTC require expert care in an experienced center. The present guideline provides guidance for healthcare professionals to make well-considered decisions together with patients and parents regarding diagnosis, treatment, and follow-up of pediatric thyroid nodules and DTC.

Causes, patterns and severity of androgen excess in 487 consecutively recruited pre- and post-pubertal children.

Objective Androgen excess in childhood is a common presentation and may signify sinister underlying pathology. Data describing its patterns and severity are scarce, limiting the information available for clinical decision processes. Here, we examined the differential diagnostic value of serum DHEAS, androstenedione (A4) and testosterone in childhood androgen excess. Design Retrospective review of all children undergoing serum androgen measurement at a single center over 5 years. Methods Serum A4 and testosterone were measured by tandem mass spectrometry and DHEAS by immunoassay. Patients with at least one increased androgen underwent phenotyping by clinical notes review. Results In 487 children with simultaneous DHEAS, A4 and testosterone measurements, we identified 199 with androgen excess (140 pre- and 59 post-pubertal). Premature adrenarche (PA) was the most common pre-pubertal diagnosis (61%), characterized by DHEAS excess in 85%, while A4 and testosterone were only increased in 26 and 9% respectively. PCOS was diagnosed in 40% of post-pubertal subjects, presenting equally frequent with isolated excess of DHEAS (29%) or testosterone (25%) or increases in both A4 and testosterone (25%). CAH patients (6%) predominantly had A4 excess (86%); testosterone and DHEAS were increased in 50 and 33% respectively. Concentrations increased above the two-fold upper limit of normal were mostly observed in PA for serum DHEAS (>20-fold in the single case of adrenocortical carcinoma) and in CAH for serum androstenedione. Conclusions Patterns and severity of childhood androgen excess provide pointers to the underlying diagnosis and can be used to guide further investigations.

Bladder dysfunction in Wolfram syndrome is highly prevalent and progresses to megacystis.

AIM: Wolfram syndrome is a rare genetic defect in WFS1 or WSF2(CISD2). It includes diabetes mellitus and insipidis, sensorineural deafness, optic atrophy, but not bladder dysfunction. However, this has appeared a common finding in our national referral clinic, and we sought to quantify this problem. METHODS: Data were collected from a multidisciplinary team managing all Wolfram patients in the UK. The following was analyzed: age, date of non-invasive urodynamics (NIU), symptoms, bladder capacity, voided volume, post-void residual and uroflow pattern. Bladder capacity was given as percentage predicted bladder capacity (PBC). Bladders were divided into normal, overactive (OAB), and underactive (UAB). Symptoms, bladder behavior, and genotyping were correlated. Data were expressed as median (interquartile range). MAIN RESULTS: Forty patients with Wolfram syndrome were identified, and 38 underwent NIU. This showed normal bladder function (n=4), OAB (n=9), UAB (n=25). Symptoms were present in only 11 children. The different patterns of bladder behavior (OAB vs. normal vs. UAB) were significantly associated with different %PBC (36 (29-59)% vs. 105 (93-233)% vs. 100 (77.5-337)%; p<0.001), and percentage emptying (100 (80-100)% vs. 100 (87-100)% vs. 69 (48-93)%; p<0.05). There was no association of genotype, symptoms and bladder behavior. Patients with megacystis were older: [13.4 (9.7-16.1) vs. 15.4 (13.9-18.7) years; p<0.05). CONCLUSION: Bladder dysfunction is very common in Wolfram syndrome (~90%), but most children cope (symptoms ~30%). With time there is a significant progression to megacystis, which may represent an underlying neuropathic myogenic failure and is likely to require intervention in the future. LEVEL OF EVIDENCE: Level II (National cohort study of prognosis).

Frequent Monitoring of C-Peptide Levels in Newly Diagnosed Type 1 Subjects Using Dried Blood Spots Collected at Home.

Objective: To evaluate an approach to measure ß-cell function by frequent testing of C-peptide concentrations in dried blood spots (DBSs). Patients: Thirty-two children, aged 7 to 17 years, with a recent diagnosis of type 1 diabetes. Design: Mixed-meal tolerance test (MMTT) within 6 and again at 12 months after diagnosis, with paired venous and DBS C-peptide sampling at 0 and 90 minutes. Weekly DBS C-peptide before and after standardized breakfasts collected at home. Results: DBS and plasma C-peptide levels (n = 115) correlated strongly (r = 0·91; P < 0.001). The Bland-Altman plot indicated good agreement. The median number of home-collected DBS cards per participant was 24 over a median of 6.9 months. Repeated DBS C-peptide levels varied considerably within and between subjects. Adjustment for corresponding home glucose measurements reduced the variance, permitting accurate description of changes over time. The correlation of the C-peptide slope over time (assessed by repeated home DBS) vs area under the curve during the two MMTTs was r = 0.73 (P < 0.001). Mixed models showed that a 1-month increase in diabetes duration was associated with 17-pmol/L decline in fasting DBS C-peptide, whereas increases of 1 mmol/L in glucose, 1 year older age at diagnosis, and 100 pmol/L higher baseline plasma C-peptide were associated with 18, 17, and 61 pmol/L higher fasting DBS C-peptide levels, respectively. In addition, glucose responsiveness decreased with longer diabetes duration. Conclusion: Our approach permitted frequent assessment of C-peptide, making it feasible to monitor ß-cell function at home. Evaluation of changes in the slope of C-peptide through this method may permit short-term evaluation of promising interventions.

Diagnosis and management of Silver-Russell syndrome: first international consensus statement.

This Consensus Statement summarizes recommendations for clinical diagnosis, investigation and management of patients with Silver-Russell syndrome (SRS), an imprinting disorder that causes prenatal and postnatal growth retardation. Considerable overlap exists between the care of individuals born small for gestational age and those with SRS. However, many specific management issues exist and evidence from controlled trials remains limited. SRS is primarily a clinical diagnosis; however, molecular testing enables confirmation of the clinical diagnosis and defines the subtype. A 'normal' result from a molecular test does not exclude the diagnosis of SRS. The management of children with SRS requires an experienced, multidisciplinary approach. Specific issues include growth failure, severe feeding difficulties, gastrointestinal problems, hypoglycaemia, body asymmetry, scoliosis, motor and speech delay and psychosocial challenges. An early emphasis on adequate nutritional status is important, with awareness that rapid postnatal weight gain might lead to subsequent increased risk of metabolic disorders. The benefits of treating patients with SRS with growth hormone include improved body composition, motor development and appetite, reduced risk of hypoglycaemia and increased height. Clinicians should be aware of possible premature adrenarche, fairly early and rapid central puberty and insulin resistance. Treatment with gonadotropin-releasing hormone analogues can delay progression of central puberty and preserve adult height potential. Long-term follow up is essential to determine the natural history and optimal management in adulthood.

Steroid Sulfatase Deficiency and Androgen Activation Before and After Puberty.

CONTEXT: Steroid sulfatase (STS) cleaves the sulfate moiety off steroid sulfates, including dehydroepiandrosterone (DHEA) sulfate (DHEAS), the inactive sulfate ester of the adrenal androgen precursor DHEA. Deficient DHEA sulfation, the opposite enzymatic reaction to that catalyzed by STS, results in androgen excess by increased conversion of DHEA to active androgens. STS deficiency (STSD) due to deletions or inactivating mutations in the X-linked STS gene manifests with ichthyosis, but androgen synthesis and metabolism in STSD have not been studied in detail yet. PATIENTS AND METHODS: We carried out a cross-sectional study in 30 males with STSD (age 6-27 y; 13 prepubertal, 5 peripubertal, and 12 postpubertal) and 38 age-, sex-, and Tanner stage-matched healthy controls. Serum and 24-hour urine steroid metabolome analysis was performed by mass spectrometry and genetic analysis of the STS gene by multiplex ligation-dependent probe amplification and Sanger sequencing. RESULTS: Genetic analysis showed STS mutations in all patients, comprising 27 complete gene deletions, 1 intragenic deletion and 2 missense mutations. STSD patients had apparently normal pubertal development. Serum and 24-hour urinary DHEAS were increased in STSD, whereas serum DHEA and testosterone were decreased. However, total 24-hour urinary androgen excretion was similar to controls, with evidence of increased 5α-reductase activity in STSD. Prepubertal healthy controls showed a marked increase in the serum DHEA to DHEAS ratio that was absent in postpubertal controls and in STSD patients of any pubertal stage. CONCLUSIONS: In STSD patients, an increased 5α-reductase activity appears to compensate for a reduced rate of androgen generation by enhancing peripheral androgen activation in affected patients. In healthy controls, we discovered a prepubertal surge in the serum DHEA to DHEAS ratio that was absent in STSD, indicative of physiologically up-regulated STS activity before puberty. This may represent a fine tuning mechanism for tissue-specific androgen activation preparing for the major changes in androgen production during puberty.

Methylation analysis and diagnostics of Beckwith-Wiedemann syndrome in 1,000 subjects.

BACKGROUND: Beckwith-Wiedemann syndrome (BWS), a congenital overgrowth disorder with variable expressivity and a predisposition to tumorigenesis, results from disordered expression and/or function of imprinted genes at chromosome 11p15.5. There are no generally agreed clinical diagnostic criteria, with molecular studies commonly performed to confirm diagnosis. In particular, methylation status analysis at two 11p15.5 imprinting control centres (IC1 and IC2) detects up to 80% of BWS cases (though low-level mosaicism may not be detected). In order to evaluate the relationship between the clinical presentation of suspected BWS and IC1/2 methylation abnormalities we reviewed the results of >1,000 referrals for molecular diagnostic testing. RESULTS: Out of 1,091 referrals, 507 (46.5%) had a positive diagnostic test for BWS. The frequency of tumours was 3.4% in those with a molecular diagnosis of BWS. Previously reported genotype-phenotype associations with paternal uniparental disomy, IC1, and IC2 epimutation groups were confirmed and potential novel associations detected. Predictive values of previously described clinical diagnostic criteria were compared and, although there were differences in their sensitivity and specificity, receiver operating characteristic (ROC) analysis demonstrated that these were not optimal in predicting 11p15.5 methylation abnormalities. Using logistic regression, we identified clinical features with the best predictive value for a positive methylation abnormality. Furthermore, we developed a weighted scoring system (sensitivity 75.9%, and specificity 81.8%) to prioritise patients presenting with the most common features of BWS, and ROC analysis demonstrated superior performance (area under the curve 0.85, 95% CI 0.83 to 0.87) compared to previous criteria. CONCLUSIONS: We suggest that this novel tool will facilitate selection of patients with suspected BWS for routine diagnostic testing and so improve the diagnosis of the disorder.

Genes, assisted reproductive technology and trans-illumination.

Genomic imprinting is a parent-of-origin allele-specific epigenetic process that is critical for normal development and health. The establishment and maintenance of normal imprinting is dependent on both cis-acting imprinting control centers, which are marked by differentially (parental allele specific) methylated marks, and trans mechanisms, which regulate the establishment and/or maintenance of the correct methylation epigenotype at the imprinting control centers. Studies of rare human imprinting disorders such as familial hydatidiform mole, Beckwith-Wiedemann syndrome and familial transient neonatal diabetes mellitus have enabled the identification of genetic (e.g., mutations in KHDC3L [C6ORF221], NLRP2 [NALP2], NLRP7 [NALP7] and ZFP57) and environmental (assisted reproductive technologies) factors that can disturb the normal trans mechanisms for imprinting establishment and/or maintenance. Here we review the clinical and molecular aspects of these imprinting disorders in order to demonstrate how the study of rare inherited disorders can illuminate the molecular characteristics of fundamental epigenetic processes, such as genomic imprinting.

Epimutation profiling in Beckwith-Wiedemann syndrome: relationship with assisted reproductive technology.

BACKGROUND: Beckwith-Wiedemann syndrome (BWS) is a congenital overgrowth disorder associated with abnormalities in 11p15.5 imprinted genes. The most common cause is loss of methylation (epimutation) at the imprinting control centre 2 (IC2/KvDMR1). Most IC2 epimutations occur sporadically but an association with conception after assisted reproductive technologies (ART) has been reported. A subgroup of IC2 epimutation cases also harbour epimutations at other imprinting centres (ICs) outside of 11p15.5. We have investigated the relationship between these multiple epimutation cases (ME+), history of ART and clinical phenotype in a cohort of 187 BWS IC2 epimutation patients. RESULTS: Methylation analysis at PLAGL1, MEST and IGF2R ICs demonstrated an over-representation of patients with abnormally low methylation (8.5%, 12% and 6% respectively). At IGF2R some patients (2%) had gain of methylation but this was also detected in controls. Though there were no significant correlations between the methylation index (MIs) at the three ICs tested, a subset of patients appeared to be susceptible to multiple epimutations (ME+) and 21.2% of ME + patients had been conceived by ART compared to 4.5% (P = 0.0033) without additional epimutations. Methylation array profiling (Illumina Goldengate®) of patients and controls (excluding 11p15.5 loci) demonstrated significant differences between patients and controls. No significant associations were found between aspects of the BWS phenotype and individual epimutations but we describe a case presenting with a post-ART BWS-like phenotype in which molecular analysis demonstrated loss of paternal allele methylation at the 11p15.5 IC1 locus (IC1 regulates imprinting of IGF2 and H19). Loss of paternal allele methylation at the IC1 is the molecular finding associated with Silver-Russell syndrome whereas BWS is associated with gain of maternal allele methylation at IC1. Further analysis demonstrated epimutations at PLAGL1 and MEST consistent with the hypothesis that the presence of multiple epimutations may be of clinical relevance. CONCLUSIONS: These findings suggest that the ME + subgroup of BWS patients are preferentially, but not exclusively, associated with a history of ART and that, though at present, there are no clear epigenotype-phenotype correlations for ME + BWS patients, non-11p15.5 IC epimutations can influence clinical phenotype.

An imprinted IMAGe: insights into growth regulation through genomic analysis of a rare disease.

Missense mutations in the imprinted gene that encodes cyclin-dependent kinase inhibitor 1C (CDKN1C, also called p57Kip2) result in a rare disorder associated with prenatal growth retardation (IMAGe syndrome). Loss-of-function mutations in CDKN1C have been previously described in the congenital overgrowth syndrome Beckwith-Wiedemann syndrome and some cancers. In contrast, a recent study by Arboleda et al. proposes that the CDKN1C mutations associated with IMAGe syndrome have a gain-of-function effect. These findings highlight how rare genetic disorders can provide important insights into the regulation of critical processes such as regulation of cell growth.