18q deletion syndrome associated with autoimmune thyroid disease presenting as hyperthyroidism

Immune Dysregulation in Patients With Chromosome 18q Deletions-Searching for Putative Loci for Autoimmunity and Immunodeficiency

Introduction

Autoimmune disorders, IgA deficiency, and allergies seem to be common among individuals with 18q deletion syndrome [OMIM 601808]. We aimed to determine the prevalence, mechanism, and genetic background of autoimmunity, immune deficiency, and allergy in a cohort of patients with 18q deletions.

Material and Methods

Medical registries and social media were used to recruit the patients. Microarray oligonucleotide comparative genomic hybridization (aCGH) (Agilent, Santa Clara, CA, USA) was performed in all patients to identify size and location of chromosome 18 deletion. Clinical evaluation and medical record collection were performed in each of the study participants. The history of autoimmune disorders, severe and/or recurrent infections, and symptoms of allergy were noted. Total immunoglobulin IgG, IgA, IgM, IgE, and IgG1-4 serum levels were measured using nephelometry and ELISA methods. Lymphocyte T subset phenotyping was performed in 24 subjects from 18q del cohort. To predict the most promising candidate genes, we used the ENDEAVOUR-a free web resource for gene prioritization.

Results

18q deletion was confirmed by means of array CGH analysis in 27 individuals, 15 (55.6%) females and 12 males, referred to the project by specialists in medical genetics, diabetology, or pediatric endocrinology between May 2015 and December 2019. The mean age at examination was 11.8 years (min-max: 4.0-33.5). Autoimmune disorders were present in 14/27 (51.8%) of the cohort. In eight of patients, symptoms of immune deficiency coexisted with autoimmunity. Allergy was reported in nine of 27 (33.4%) patients. Over 89% of patients presented with at list one type of immunoglobulin (IgA, IgM, IgG, IgE, and IgG1-4) deficiency and eight of 25 (32%) had abnormalities in at least two major immunoglobulin (IgG, IgA, IgM) measurements (CVID-like phenotype). Patients with 18q del exhibited a significantly decreased CD4, Treg FOXP3+, TregFOXP3+Helios+, and TemCD4 cell numbers in comparison with the control groups of 24 T1DM patients and 28 healthy controls.

Conclusions

Patients with 18q deletions frequently suffer from autoimmune disorders, recurrent infections, and allergy due to immune dysregulation presenting with variable antibody deficiencies and T-regulatory cell deficiency (CD4+CD25+CD127lowFOXP3+). The spectrum of speculations regarding which gene might be responsible for such phenotype ranges from single gene haploinsufficiency to deletion of a cluster of immunogenes located distally to 18q21.

Unusual Endocrinopathies in 18q Deletion Syndrome: Pseudoparathyroidism and Hyper-/Hypo-Thyroidism

Objective

To describe new and unusual endocrinopathies in children with de novo 18q deletion (18q-) syndrome.

Methods

We describe 2 patients who have atypical thyroid conditions and 1 who also developed symptomatic hypocalcemia.

Results

The first patient developed hyperthyroidism at the age of 3 years, with a free thyroxine level of 3.9 (range, 0.8-1.8) ng/dL. Thyroid peroxidase antibodies were 262 (range, 0-32) IU/mL, and thyroid-stimulating immunoglobulin antibodies were 384% (range, 0-139%). On low-dose methimazole treatment, she developed hypothyroidism. Thyroid-stimulating hormone (TSH) level was 163 (range, 0.4-4.5) mIU/mL. Moreover, she later developed growth hormone deficiency. The second patient developed hypothyroidism at the age of 4 years, with a TSH level of 46 mIU/mL. However, TSH remained elevated at levels of 10 to 24 mIU/mL for 3 years, despite appropriate treatment, suggesting TSH resistance. She then developed hypocalcemic seizures and was diagnosed with pseudohypoparathyroidism. Her total calcium level was 6.6 (range, 8.5-10.5) mg/dL and parathyroid hormone level was 432 (range, 15-65) pg/dL.

Conclusion

The first patient had a mixed picture of autoimmune hypothyroidism and hyperthyroidism, requiring a combination of methimazole and levothyroxine to achieve a euthyroid state. For the second patient, the mild TSH resistance was possibly the early suggestion of a parathyroid hormone resistant state. Although growth hormone deficiency and hypothyroidism are common in patients with 18q- syndrome, the occurrence of hyperthyroidism due to Graves’ disease with the coexistence of Hashimoto’s hypothyroidism is rare. Pseudohypoparathyroidism has not yet been reported in patients with 18q- syndrome.

Hashimoto's Thyroiditis and Graves' Disease in Genetic Syndromes in Pediatric Age

Autoimmune thyroid diseases (AITDs), including Hashimoto’s thyroiditis (HT) and Graves’ disease (GD), are the most common cause of acquired thyroid disorder during childhood and adolescence. Our purpose was to assess the main features of AITDs when they occur in association with genetic syndromes. We conducted a systematic review of the literature, covering the last 20 years, through MEDLINE via PubMed and EMBASE databases, in order to identify studies focused on the relation between AITDs and genetic syndromes in children and adolescents. From the 1654 references initially identified, 90 articles were selected for our final evaluation. Turner syndrome, Down syndrome, Klinefelter syndrome, neurofibromatosis type 1, Noonan syndrome, 22q11.2 deletion syndrome, Prader–Willi syndrome, Williams syndrome and 18q deletion syndrome were evaluated. Our analysis confirmed that AITDs show peculiar phenotypic patterns when they occur in association with some genetic disorders, especially chromosomopathies. To improve clinical practice and healthcare in children and adolescents with genetic syndromes, an accurate screening and monitoring of thyroid function and autoimmunity should be performed. Furthermore, maintaining adequate thyroid hormone levels is important to avoid aggravating growth and cognitive deficits that are not infrequently present in the syndromes analyzed.

Features of two cases with 18q deletion syndrome

The 18q Deletion syndrome is seen in 1 out of 10 000 live births. The main features of the syndrome are short stature, hearing loss, hypotonia, mental retardation, endocrine disorders and autoimmunity. Here, we present 2 patients with this syndrome admitted to our clinic who were found to have insulin resistance in addition to mental retardation, short stature, autoimmune thyroiditis and hearing loss. The need to perform a karyogram analysis in cases presenting with these features is emphasized.

Growth monitoring still has a place in selected populations of children

In 1998, a multiprofessional group developed a consensus on growth monitoring in the UK. While routine serial measurements were not recommended in healthy children, it is clear that there is a subset of children at increased risk of growth-modifying disease who may benefit from growth monitoring. This subset includes children with genetic disorders at increased risk of thyroid dysfunction. Symptoms and signs of thyroid dysfunction are non-specific in the early stages of disease and are easily mistaken for features of an underlying genetic disorder. In this article, we report the case of a 2.8-year-old girl with 18q deletion syndrome who was profoundly weak, hypotonic and poorly responsive at diagnosis of Grave's disease. She was tall and her bone age was 2 years advanced, indicating long-standing disease. Growth monitoring of this patient should have enabled earlier diagnosis and avoided a serious and potentially fatal episode.