22q11.2 microdeletion and increased risk for type 2 diabetes

Real-World Treatment of Schizophrenia in Adults With a 22q11.2 Microdeletion: Traitement dans le monde réel de la schizophrénie chez des adultes atteints du syndrome de microdélétion 22q11.2

OBJECTIVE

One in every 4 individuals born with a 22q11.2 microdeletion will develop schizophrenia. Thirty years of clinical genetic testing capability have enabled detection of this major molecular susceptibility for psychotic illness. However, there is limited literature on the treatment of schizophrenia in individuals with a 22q11.2 microdeletion, particularly regarding the issue of treatment resistance.

METHODS

From a large, well-characterized adult cohort with a typical 22q11.2 microdeletion followed for up to 25 years at a specialty clinic, we studied all 107 adults (49 females, 45.8%) meeting the criteria for schizophrenia or schizoaffective disorder. We performed a comprehensive review of lifetime (1,801 patient-years) psychiatric records to determine treatments used and the prevalence of treatment-resistant schizophrenia (TRS). We used Clinical Global Impression-Improvement (CGI-I) scores to compare within-individual responses to clozapine and nonclozapine antipsychotics. For a subgroup with contemporary data (n = 88, 82.2%), we examined antipsychotics and dosage at the last follow-up.

RESULTS

Lifetime treatments involved on average 4 different antipsychotic medications per individual. Sixty-three (58.9%) individuals met the study criteria for TRS, a significantly greater proportion than for a community-based comparison (42.9%; χ2 = 10.38, df = 1, p < 0.01). The non-TRS group was enriched for individuals with genetic diagnosis before schizophrenia diagnosis. Within-person treatment response in TRS was significantly better for clozapine than for nonclozapine antipsychotics (p < 0.0001). At the last follow-up, clozapine was the most common antipsychotic prescribed, followed by olanzapine, risperidone, and paliperidone. Total antipsychotic chlorpromazine equivalent dosages were in typical clinical ranges (median: 450 mg; interquartile range: 300, 750 mg).

CONCLUSION

The results for this large sample indicate that patients with 22q11.2 microdeletion have an increased propensity to treatment resistance. The findings provide evidence about how genetic diagnosis can inform clinical psychiatric management and could help reduce treatment delays. Further research is needed to shed light on the pathophysiology of antipsychotic response and on strategies to optimize outcomes.

PLAIN LANGUAGE SUMMARY TITLE

Real-world treatment of schizophrenia in adults with a 22q11.2 microdeletion.

Obesity and Cardiometabolic Disease: Insights From Genetic Studies

Obesity is a highly prevalent chronic disease and major driver of both atherosclerotic heart disease and heart failure. Obesity is also a heritable neuronal disease with heritability estimates of up to 70%. In this work I review how common genetic variants, usually with small effect sizes, contribute to the risk for developing obesity and cardiometabolic disease in the majority of people and how this can be further modulated by environmental factors. In some individuals, rare genetic variants with large effect sizes can influence the risk of developing obesity, in some cases in a Mendelian manner. I also address how identification of these rare variants has led to fundamental biologic insights into how satiety and reward are biologic processes, has led to more personalized treatments, and has identified potential novel drug treatments. Biologic insights derived from genetic studies of obesity have also improved our understanding of the causal mediators between obesity and cardiovascular disease. A major limitation of studies to date is that they involved mostly people of European ancestry. Studying more diverse populations will improve our understanding of obesity and cardiometabolic disease. Lessons derived from genetic studies make a compelling case for increasing accessibility to therapies that have sustained efficacy in managing obesity and improving health. This increased knowledge must also inform public health initiatives that will reduce the prevalence of obesity in the coming decades.

DGCR2 targeting affibody molecules for delivery of drugs and imaging reagents to human beta cells

A distinctive feature of both type 1 and type 2 diabetes is the waning of insulin-secreting beta cells in the pancreas. New methods for direct and specific targeting of the beta cells could provide platforms for delivery of pharmaceutical reagents. Imaging techniques such as Positron Emission Tomography (PET) rely on the efficient and specific delivery of imaging reagents, and could greatly improve our understanding of diabetes etiology as well as providing biomarkers for viable beta-cell mass in tissue, in both pancreas and in islet grafts.The DiGeorge Syndrome Critical Region Gene 2 (DGCR2) protein has been suggested as a beta-cell specific protein in the pancreas, but so far there has been a lack of available high-affinity binders suitable for targeted drug delivery or molecular imaging. Affibody molecules belong to a class of small affinity proteins with excellent properties for molecular imaging. Here, we further validate the presence of DGCR2 in pancreatic and stem cell (SC)-derived beta cells, and then describe the generation and selection of several Affibody molecules candidates that target human DGCR2. Using an in-house developed directed evolution method, new DGCR2-binding Affibody molecules were generated and evaluated for thermal stability and affinity. The Affibody molecules variants were further developed as targeting agents for delivering imaging reagents to beta cell. The Affibody molecule ZDGCR2:AM106 displayed nanomolar affinity, suitable stability and biodistribution, with negligible toxicity to islets, qualifying it as a suitable lead candidate for further development as a tool for specific delivery of drugs and imaging reagents to beta cells.

Hearing loss and history of otolaryngological conditions in adults with microdeletion 22q11.2

Previous studies have shown that the 22q11.2 microdeletion, associated with 22q11.2 deletion syndrome (22q11.2DS), conveys an increased risk of chronic otitis media, and hearing loss at young age. This study reports on hearing loss and history of otolaryngological conditions in adults with 22q11.2DS. We conducted a retrospective study of 60 adults with 22q11.2DS (41.7% male) at median age 25 (range 16-74) years who had visited an otolaryngologist and audiologist for routine assessment at a 22q11.2 expert center. Demographic, genetic, audiometric, and otolaryngological data were systematically extracted from the medical files. Regression analysis was used to evaluate the effect of age, sex, full-scale intelligence quotient, and history of chronic otitis media on the severity of hearing loss. Hearing loss, mostly high-frequency sensorineural, was found in 78.3% of adults. Higher age and history of chronic otitis media were associated with more severe hearing loss. Otolaryngological conditions with possible treatment implications included chronic otitis media (56.7%), globus pharyngeus (18.3%), balance problems (16.7%), and obstructive sleep apnea (8.3%). The results suggest that  in 22q11.2DS, high-frequency hearing loss appears to be common from a young adult age, and often unrecognized. Therefore, we recommend periodic audiometric screening in all adults, including high-frequency ranges.

Preclinical evaluation of Affibody molecule for PET imaging of human pancreatic islets derived from stem cells

BACKGROUND

Beta-cell replacement methods such as transplantation of isolated donor islets have been proposed as a curative treatment of type 1 diabetes, but widespread application is challenging due to shortages of donor tissue and the need for continuous immunosuppressive treatments. Stem-cell-derived islets have been suggested as an alternative source of beta cells, but face transplantation protocols optimization difficulties, mainly due to a lack of available methods and markers to directly monitor grafts survival, as well as their localization and function. Molecular imaging techniques and particularly positron emission tomography has been suggested as a tool for monitoring the fate of islets after clinical transplantation. The integral membrane protein DGCR2 has been demonstrated to be a potential pancreatic islet biomarker, with specific expression on insulin-positive human embryonic stem-cell-derived pancreatic progenitor cells. The candidate Affibody molecule ZDGCR2:AM106 was radiolabeled with fluorine-18 using a novel click chemistry-based approach. The resulting positron emission tomography tracer [18F]ZDGCR2:AM106 was evaluated for binding to recombinant human DGCR2 and cryosections of stem-cell-derived islets, as well as in vivo using an immune-deficient mouse model transplanted with stem-cell-derived islets. Biodistribution of the [18F]ZDGCR2:AM106 was also assessed in healthy rats and pigs.

RESULTS

[18F]ZDGCR2:AM106 was successfully synthesized with high radiochemical purity and yield via a pretargeting approach. [18F]ZDGCR2:AM106 retained binding to recombinant human DCGR2 as well as to cryosectioned stem-cell-derived islets, but in vivo binding to native pancreatic tissue in both rat and pig was low. However, in vivo uptake of [18F]ZDGCR2:AM106 in stem-cell-derived islets transplanted in the immunodeficient mice was observed, albeit only within the early imaging frames after injection of the radiotracer.

CONCLUSION

Targeting of DGCR2 is a promising approach for in vivo detection of stem-cell-derived islets grafts by molecular imaging. The synthesis of [18F]ZDGCR2:AM106 was successfully performed via a pretargeting method to label a site-specific covalently bonded fluorine-18 to the Affibody molecule. However, the rapid washout of [18F]ZDGCR2:AM106 from the stem-cell-derived islets graft indicates that dissociation kinetics can be improved. Further studies using alternative binders of similar classes with improved binding potential are warranted.

Clinically Relevant Genetic Considerations for Patients With Tetralogy of Fallot

Genetic changes affect embryogenesis, cardiac and extracardiac phenotype, development, later onset conditions, and both short- and long-term outcomes and comorbidities in the increasing population of individuals with tetralogy of Fallot (TOF). In this review, we focus on current knowledge about clinically relevant genetics for patients with TOF across the lifespan. The latest findings for TOF genetics that are pertinent to day-to-day practice and lifelong management are highlighted: morbidity/mortality, cardiac/extracardiac features, including neurodevelopmental expression, and recent changes to prenatal screening and diagnostics. Genome-wide microarray is the first-line clinical genetic test for TOF across the lifespan, detecting relevant structural changes including the most common for TOF, the 22q11.2 microdeletion. Accumulating evidence illustrates opportunities for advances in understanding and care that may arise from genetic diagnosis at any age. We also glimpse into the near future when the multigenic nature of TOF will be more fully revealed, further enhancing possibilities for preventive care. Precision medicine is nigh.

Polygenic risk for triglyceride levels in the presence of a high impact rare variant

BACKGROUND

Elevated triglyceride (TG) levels are a heritable and modifiable risk factor for cardiovascular disease and have well-established associations with common genetic variation captured in a polygenic risk score (PRS). In young adulthood, the 22q11.2 microdeletion conveys a 2-fold increased risk for mild-moderate hypertriglyceridemia. This study aimed to assess the role of the TG-PRS in individuals with this elevated baseline risk for mild-moderate hypertriglyceridemia.

METHODS

We studied a deeply phenotyped cohort of adults (n = 157, median age 34 years) with a 22q11.2 microdeletion and available genome sequencing, lipid level, and other clinical data. The association between a previously developed TG-PRS and TG levels was assessed using a multivariable regression model adjusting for effects of sex, BMI, and other covariates. We also constructed receiver operating characteristic (ROC) curves using logistic regression models to assess the ability of TG-PRS and significant clinical variables to predict mild-moderate hypertriglyceridemia status.

RESULTS

The TG-PRS was a significant predictor of TG-levels (p = 1.52E-04), along with male sex and BMI, in a multivariable model (pmodel = 7.26E-05). The effect of TG-PRS appeared to be slightly stronger in individuals with obesity (BMI ≥ 30) (beta = 0.4617) than without (beta = 0.1778), in a model unadjusted for other covariates (p-interaction = 0.045). Among ROC curves constructed, the inclusion of TG-PRS, sex, and BMI as predictor variables produced the greatest area under the curve (0.749) for classifying those with mild-moderate hypertriglyceridemia, achieving an optimal sensitivity and specificity of 0.746 and 0.707, respectively.

CONCLUSIONS

These results demonstrate that in addition to significant effects of sex and BMI, genome-wide common variation captured in a PRS also contributes to the variable expression of the 22q11.2 microdeletion with respect to elevated TG levels.

Copy Number Variations in Neuropsychiatric Disorders

Neuropsychiatric disorders are complex conditions that represent a significant global health burden with complex and multifactorial etiologies. Technological advances in recent years have improved our understanding of the genetic architecture of the major neuropsychiatric disorders and the genetic loci involved. Previous studies mainly investigated genome-wide significant SNPs to elucidate the cross-disorder and disorder-specific genetic basis of neuropsychiatric disorders. Although copy number variations represent a major source of genetic variations, they are known risk factors in developing a variety of human disorders, including certain neuropsychiatric diseases. In this review, we demonstrate the current understanding of CNVs contributing to liability for schizophrenia, bipolar disorder, and major depressive disorder.

Chromosome 22q11.2 Deletion Syndrome: A Comprehensive Review of Molecular Genetics in the Context of Multidisciplinary Clinical Approach

The 22q11.2 deletion syndrome is a multisystemic disorder characterized by a marked variability of phenotypic features, making the diagnosis challenging for clinicians. The wide spectrum of clinical manifestations includes congenital heart defects-most frequently conotruncal cardiac anomalies-thymic hypoplasia and predominating cellular immune deficiency, laryngeal developmental defects, midline anomalies with cleft palate and velar insufficiency, structural airway defects, facial dysmorphism, parathyroid and thyroid gland hormonal dysfunctions, speech delay, developmental delay, and neurocognitive and psychiatric disorders. Significant progress has been made in understanding the complex molecular genetic etiology of 22q11.2 deletion syndrome underpinning the heterogeneity of clinical manifestations. The deletion is caused by chromosomal rearrangements in meiosis and is mediated by non-allelic homologous recombination events between low copy repeats or segmental duplications in the 22q11.2 region. A range of genetic modifiers and environmental factors, as well as the impact of hemizygosity on the remaining allele, contribute to the intricate genotype-phenotype relationships. This comprehensive review has been aimed at highlighting the molecular genetic background of 22q11.2 deletion syndrome in correlation with a clinical multidisciplinary approach.

Updated clinical practice recommendations for managing adults with 22q11.2 deletion syndrome

This review aimed to update the clinical practice guidelines for managing adults with 22q11.2 deletion syndrome (22q11.2DS). The 22q11.2 Society recruited expert clinicians worldwide to revise the original clinical practice guidelines for adults in a stepwise process according to best practices: (1) a systematic literature search (1992-2021), (2) study selection and synthesis by clinical experts from 8 countries, covering 24 subspecialties, and (3) formulation of consensus recommendations based on the literature and further shaped by patient advocate survey results. Of 2441 22q11.2DS-relevant publications initially identified, 2344 received full-text review, with 2318 meeting inclusion criteria (clinical care relevance to 22q11.2DS) including 894 with potential relevance to adults. The evidence base remains limited. Thus multidisciplinary recommendations represent statements of current best practice for this evolving field, informed by the available literature. These recommendations provide guidance for the recognition, evaluation, surveillance, and management of the many emerging and chronic 22q11.2DS-associated multisystem morbidities relevant to adults. The recommendations also address key genetic counseling and psychosocial considerations for the increasing numbers of adults with this complex condition.

Adult-onset obstructive sleep apnea and pediatric pharyngoplasty in 22q11.2 deletion syndrome

OBJECTIVE/BACKGROUND

We aimed to evaluate adult-onset obstructive sleep apnea (OSA) and related risk factors, including history of pediatric palatal/pharyngeal surgery to remediate velopharyngeal dysfunction, in 22q11.2 deletion syndrome (22q11.2DS).

PATIENTS/METHODS

Using a retrospective cohort design and standard sleep study-based criteria, we determined presence of adult-onset OSA (age ≥16 years) and relevant variables through comprehensive chart review in a well-characterized cohort of 387 adults with typical 22q11.2 microdeletions (51.4% female, median age 32.3, interquartile range 25.0-42.5, years). We used multivariate logistic regression to identify independent risk factors for OSA.

RESULTS

Of the 73 adults with sleep study data, 39 (53.4%) met criteria for OSA at median age 33.6 (interquartile range 24.0-40.7) years, indicating a minimum OSA prevalence of 10.1% in this 22q11.2DS cohort. History of pediatric pharyngoplasty (odds ratio 2.56, 95% confidence interval 1.15-5.70) was a significant independent predictor of adult-onset OSA, while accounting for other significant independent predictors (asthma, higher body mass index, older age), and for male sex. An estimated 65.5% of those prescribed continuous positive airway pressure therapy were reported as adherent.

CONCLUSIONS

In addition to factors of known importance in the general population, delayed effects of pediatric pharyngoplasty may contribute to risk of adult-onset OSA in individuals with 22q11.2DS. The results support increased index of suspicion for OSA in adults with a 22q11.2 microdeletion. Future research with this and other homogeneous genetic models may help to improve outcomes and to better understand genetic and modifiable risk factors for OSA.

Reproductive Outcomes in Adults with 22q11.2 Deletion Syndrome

The 22q11.2 microdeletion and its associated conditions could affect reproductive outcomes but there is limited information on this important area. We investigated reproductive outcomes in a sample of 368 adults with typical 22q11.2 deletions (median age 32.8, range 17.9-76.3 years; 195 females), and without moderate-severe intellectual disability, who were followed prospectively. We examined all reproductive outcomes and possible effects of diagnosis as a transmitting parent on these outcomes. We used logistic regression to investigate factors relevant to reproductive fitness (liveborn offspring). There were 63 (17.1%) individuals with 157 pregnancy outcomes, 94 (60.3%) of which involved live births. Amongst the remainder involving a form of loss, were seven (5.77%) stillbirths, significantly greater than population norms (p < 0.0001). For 35 (55.6%) individuals, diagnosis of 22q11.2 deletion syndrome (22q11.2DS) followed diagnosis of an offspring, with disproportionately fewer individuals had major congenital heart disease (CHD) in that transmitting parent subgroup. The regression model indicated that major CHD, in addition to previously identified factors, was a significant independent predictor of reduced reproductive fitness. There was evidence of persisting diagnostic delay and limited prenatal genetic testing. The findings indicate that pregnancy loss is an important health issue for adults with 22q11.2DS. CHD and/or its absence is a factor to consider in reproductive outcome research. Further studies are warranted to better appreciate factors that may contribute to reproductive outcomes, including technological advances. The results suggest the need for ongoing efforts to provide optimal education and supports to individuals with 22q11.2DS, and their clinicians, around reproductive issues and early diagnosis.

Hypoparathyroidism and late-onset hypogonadism in an adult male with familial 22q11.2 deletion syndrome: a case report with 3-year follow-up and review of the literature

BACKGROUND

22q11.2 deletion syndrome (DiGeorge syndrome) is associated with multiple organ dysfunctions such as cardiac defects, immunodeficiency, and hypoplasia of parathyroid glands. Moreover, the phenotype of 22q11.2 DS has clinical variability and heterogeneity.

CASE PRESENTATION

In this report, we present the case of a 35-year-old patient with a past medical history that included recurrent infections, mild learning difficulties in childhood, pediatric obesity, and cataract. He was admitted to the endocrinology department for the management of hypogonadism and hypocalcemia. During the 3-year follow-up, the patient gradually developed primary hypoparathyroidism, hypogonadism, chronic renal failure, and heart failure, and his medical condition deteriorated. Meanwhile, in order to improve clinicians' awareness of the endocrine manifestations of adult 22q11.2 DS and reduce missed diagnoses, we reviewed 28 case reports of adult 22q11.2 DS to analyze the clinical characteristics.

DISCUSSION

Here, we report the case of a young man diagnosed with 22q11.2 DS presented a rare combination of multiple endocrine disorders. This is the first time that a patient with 22q11.2DS had late-onset hypogonadism caused by primary testicular failure combined with decreased pituitary gonadotropin reserve in a patient with 22q11.2DS.

Adult Height, 22q11.2 Deletion Extent, and Short Stature in 22q11.2 Deletion Syndrome

The 22q11.2 deletion syndrome (22q11.2DS) manifests as a wide range of medical conditions across a number of systems. Pediatric growth deficiency with some catch-up growth is reported, but there are few studies of final adult height. We aimed to investigate how final adult height in 22q11.2DS compared with general population norms, and to examine predictors of short stature in in a cohort of 397 adults with 22q11.2DS (aged 17.6–76.3 years) with confirmed typical 22q11.2 microdeletion (overlapping the LCR22A to LCR22B region). We defined short stature as <3rd percentile using population norms. For the subset (n = 314, 79.1%) with 22q11.2 deletion extent, we used a binomial logistic regression model to predict short stature in 22q11.2DS, accounting for effects of sex, age, ancestry, major congenital heart disease (CHD), moderate-to-severe intellectual disability (ID), and 22q11.2 deletion extent. Adult height in 22q11.2DS showed a normal distribution but with a shift to the left, compared with population norms. Those with short stature represented 22.7% of the 22q11.2DS sample, 7.6-fold greater than population expectations (p < 0.0001). In the regression model, moderate-to-severe ID, major CHD, and the common LCR22A-LCR22D (A-D) deletion were significant independent risk factors for short stature while accounting for other factors (model p = 0.0004). The results suggest that the 22q11.2 microdeletion has a significant effect on final adult height distribution, and on short stature with effects appearing to arise from reduced gene dosage involving both the proximal and distal sub-regions of the A-D region. Future studies involving larger sample sizes with proximal nested 22q11.2 deletions, longitudinal lifetime data, parental heights, and genotype data will be valuable.

Hypertriglyceridemia in young adults with a 22q11.2 microdeletion

OBJECTIVE

Mild to moderate hypertriglyceridemia is a condition often associated with obesity and diabetes, with as yet incomplete knowledge of underlying genetic architecture. The 22q11.2 microdeletion is associated with multimorbidity, including increased risk of obesity and diabetes. In this study, we sought to investigate whether the 22q11.2 microdeletion was associated with mild to moderate hypertriglyceridemia (1.7-10 mmol/L).

DESIGN

This was a cohort study comparing 6793 population-based adults and 267 with a 22q11.2 microdeletion aged 17-69 years, excluding those with diabetes or on statins.

METHODS

We used binomial logistic regression modeling to identify predictors of hypertriglyceridemia, accounting for the 22q11.2 microdeletion, male sex, BMI, ethnicity, age, and antipsychotic medications.

RESULTS

The 22q11.2 microdeletion was a significant independent predictor of mild to moderate hypertriglyceridemia (odds ratio (OR): 2.35, 95% CI: 1.70-3.26). All other factors examined were also significant predictors (OR: 1.23-2.10), except for antipsychotic medication use. Within the 22q11.2 microdeletion subgroup, only male sex (OR: 3.10, 95% CI: 1.77-5.44) and BMI (OR: 1.63, 95% CI: 1.14-1.98) were significant predictors of hypertriglyceridemia, evident at mean age 31.2 years.

CONCLUSIONS

The 22q11.2 microdeletion is associated with hypertriglyceridemia even when accounting for other known risk factors for elevated triglycerides. This effect is seen in young adulthood (76.6% were <40 years), in the absence of diabetes, and irrespective of antipsychotics, suggesting that the 22q11.2 microdeletion may represent an unrecognized genetic risk factor for hypertriglyceridemia, providing novel opportunities for animal and cellular models. Early dyslipidemia screening and management strategies would appear prudent for individuals with 22q11.2 microdeletions.

Ocular findings in 22q11.2 deletion syndrome: A systematic literature review and results of a Dutch multicenter study

The 22q11.2 deletion syndrome (22q11.2DS) is a multisystem disorder with an estimated prevalence of 1:3000 live births. Manifestations show a marked variability in expression and include speech‐ and language delay, intellectual disability, and neuropsychiatric disorders. We aim to provide an overview of ocular findings in 22q11.2DS in order to optimize recommendations for ophthalmic screening. We combined results from a systematic literature review with results from a multicenter cross‐sectional study of patients with 22q11.2DS who were assessed by an ophthalmologist. Our systematic literature search yielded four articles, describing 270 patients. We included 132 patients in our cross‐sectional study (median age 8.9 [range 0–56] years). Most reported ocular findings were retinal vascular tortuosity (32%–78%), posterior embryotoxon (22%–50%), eye lid hooding (20%–67%), strabismus (12%–36%), amblyopia (2%–11%), ptosis (4%–6%), and refractive errors, of which hyperopia (6%–48%) and astigmatism (3%–23%) were most common. Visual acuity was (near) normal in most patients (91%–94%). Refractive errors, strabismus, and amblyopia are treatable conditions that are frequently present in patients with 22q11.2DS and should be corrected at an early stage. Therefore, in 22q11.2DS, we recommend ophthalmic and orthoptic screening at the age of 3 years or at diagnosis, and a low‐threshold referral in adults.