Characterization of Autoimmune Thyroid Disease in a Cohort of 73 Paediatric Patients Affected by 22q11.2 Deletion Syndrome: Longitudinal Single-Centre Study

Endocrine manifestations in adults with 22q11.2 deletion syndrome: a retrospective single-center cohort study

INTRODUCTION AND OBJECTIVE

Patients with the 22q11.2 deletion syndrome (22q11DS) frequently display cardiological and psychiatric diseases, but are also at increased risk for endocrine manifestations. The aim of this study was to evaluate the screening, prevalence, and management of hypoparathyroidism and thyroid disease in patients with 22q11DS, to evaluate the metabolic profile, and to compare these results with current literature and guidelines.

DESIGN

We performed a retrospective study of patients with genetically confirmed 22q11DS, followed at the center for human genetics of the University Hospitals Leuven, resulting in a cohort of 75 patients. Medical history, medication, and laboratory results concerning hypoparathyroidism, thyroid dysfunction, and the metabolic profile were collected.

RESULTS

Of the total cohort, 26 patients (35%) had at least one hypocalcaemic episode. During hypocalcaemia, parathyroid hormone (PTH) was measured in only 12 patients with 11 having normal or low PTH, confirming a diagnosis of hypoparathyroidism. Recurrent episodes of hypocalcaemia occurred in seventeen patients (23%). Adherence to the guidelines was low, with 13% of patients having a yearly serum calcium evaluation, 12% receiving daily calcium supplements, and 20% receiving non-active vitamin D. Hypothyroidism was present in 31 patients (44%) and hyperthyroidism in 6 patients (8%). Information on body mass index (BMI) was available in 52 patients (69%), of which 38% were obese (BMI ≥ 30 kg/m2).

CONCLUSION

Hypoparathyroidism, hypothyroidism, and obesity are common endocrine manifestations in patients with 22q11DS but are probably underdiagnosed and undertreated, indicating the need for multidisciplinary follow-up including an endocrinologist.

Understanding the Variability of 22q11.2 Deletion Syndrome: The Role of Epigenetic Factors

Initially described as a triad of immunodeficiency, congenital heart defects and hypoparathyroidism, 22q11.2 deletion syndrome (22q11.2DS) now encompasses a great amount of abnormalities involving different systems. Approximately 85% of patients share a 3 Mb 22q11.2 region of hemizygous deletion in which 46 protein-coding genes are included. However, the hemizygosity of the genes of this region cannot fully explain the clinical phenotype and the phenotypic variability observed among patients. Additional mutations in genes located outside the deleted region, leading to "dual diagnosis", have been described in 1% of patients. In some cases, the hemizygosity of the 22q11.2 region unmasks autosomal recessive conditions due to additional mutations on the non-deleted allele. Some of the deleted genes play a crucial role in gene expression regulation pathways, involving the whole genome. Typical miRNA expression patterns have been identified in 22q11.2DS, due to an alteration in miRNA biogenesis, affecting the expression of several target genes. Also, a methylation epi-signature in CpG islands differentiating patients from controls has been defined. Herein, we summarize the evidence on the genetic and epigenetic mechanisms implicated in the pathogenesis of the clinical manifestations of 22q11.2 DS. The review of the literature confirms the hypothesis that the 22q11.2DS phenotype results from a network of interactions between deleted protein-coding genes and altered epigenetic regulation.

Hypoparathyroidism Associated with Benign Thyroid Nodules in DiGeorge-like Syndrome: A Rare Case Report and Literature Review

BACKGROUND

DiGeorge-like syndrome (DGLS) is a rare genetic disorder due to the presence of the same classical clinical manifestations of DiGeorge syndrome (DGS) without its typical deletion. In the DGLS phenotype, hypoparathyroidism seldom occurs and is considered rare. In DGS, hypocalcemia affects up to 70% of patients, and a considerable share often has asymptomatic thyroid abnormalities.

CASE PRESENTATION

In this study, we describe an unusual case of a 16-year-old patient with DGLS due to a duplication of 365 kb in the 20p11.22 region, affected by hypoparathyroidism associated with thyroid nodule. The intraoperative parathyroid evaluation ruled out agenesis as a cause of hypoparathyroidism. In addition, we carried out a thorough literature review from 2010 to 2023 of DGLS cases using specific keywords, such as "22q11.2 deletion syndrome", "Di- George-like Syndrome", "hypoparathyroidism", "thyroid", and "children", analyzing 119 patients with DGLS.

CONCLUSION

Interestingly enough, the present case represents, to our knowledge, the first report of a patient with DGLS associated with hypoparathyroidism and the presence of thyroid nodules where an intraoperative observation reported a non-functional parathyroid gland.

Risk of thyroid neoplasms in patients with 22q11.2 deletion and DiGeorge-like syndromes: an insight for follow-up

Introduction

The chromosome 22q11.2 deletion syndrome comprises phenotypically similar diseases characterized by abnormal development of the third and fourth branchial arches, resulting in variable combinations of congenital heart defects, dysmorphisms, hypocalcemia, palatal dysfunction, developmental or neuropsychiatric disorders, and impairment of the immune system due to thymic dysfunction. Other genetic syndromes, often called DiGeorge-like, share clinical and immunological features with 22q11.2 deletion syndrome. This syndrome has been rarely associated with malignancies, mainly hematological but also hepatic, renal, and cerebral. Rarely, malignancies in the head and neck region have been described, although no aggregate of data on the development of thyroid neoplasms in patients with this clinical phenotype has been conducted so far.

Materials and methods

To characterize this possible association, a multicenter survey was made. Thus, we present a case series of five pediatric patients with 22q11.2 deletion syndrome or DiGeorge-like syndrome who were occasionally found with confirmed or highly suspected neoplasms of the thyroid gland during their follow-up. In three cases, malignancies were histologically confirmed, but their outcome was good due to an early recognition of suspicious nodules and precocious surgery.

Conclusions

This study underlines for clinicians the higher risk of neoplasms in the head and neck district for patients affected by these syndromes. It also emphasizes the importance of a prolonged clinical and ultrasound follow-up for patients with this clinical and immunological phenotype.

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.

Case report: Effectiveness of sirolimus in treating partial DiGeorge Syndrome with Autoimmune Lymphoproliferative Syndrome (ALPS)-like features

BACKGROUND

DiGeorge Syndrome (DGS) is a rare disease associated with 22q11.2 chromosomal microdeletion, also known as a velocardiofacial syndrome, based on the frequent involvements of the palate, facial, and heart problems. Hematologic autoimmunity is rare in DGS but presents with a refractory course and poor prognosis. Herein, we report a case of partial DGS in a patient with refractory immune cytopenia and autoimmune lymphoproliferative syndrome (ALPS)-like manifestations.

CASE DESCRIPTION

A 10-year-old boy with growth retardation presented initially with a ventricular septal defect at 7 months old, which had been repaired soon after. The patient suffered from thrombocytopenia and progressed into chronic refractory immune thrombocytopenia (ITP) at 30 months old. One year later, the patient developed multilineage cytopenias including thrombocytopenia, neutropenia, and anemia. First-line treatment of ITP, like high-dose dexamethasone and intravenous immunoglobulin, had little or short-term effect on controlling symptoms. Whole-exome sequencing revealed the presence of a de novo heterozygous 2.520 Mb deletion on chromosome 22q11.21. Moreover, decreased proportion of naive T cells and elevated double-negative T cells were found. The patient was given sirolimus therapy (1.5 mg/m², actual blood concentration range: 4.0-5.2 ng/ml) without adding other immunosuppressive agents. The whole blood cell count was gradually restored after a month, and the disease severity was soothed with less frequency of infections and bleeding events. Decreased spleen size and restrained lymph node expansion were achieved after 3-month sirolimus monotherapy.

CONCLUSIONS

This case is the first description on the efficacy of sirolimus monotherapy to treat refractory multilineage cytopenias of DGS presented with ALPS-like features.