22q11.2 Microduplication with thyroid hemiagenesis

Hemiagenesis of the thyroid gland detected by coincidence-what is the clinical relevance? : Case report and review of the literature

Hemiagenesis of the thyroid gland (THA) represents a rare congenital anomaly. It is characterized by the absence of one thyroid lobe, and sometimes the isthmus as well. It can occur with all kinds of other thyroid pathologies that may be present in the remaining thyroid lobe. A case of a 21-year-old male patient is presented; he sought a thyroid consultation because of hair loss, fatigue, and problems concentrating, thus raising the suspicion of hypothyroidism. Thyroid function was normal, but sonography of the thyroid gland revealed THA of the left lobe and the isthmus. The current knowledge concerning the genesis and the clinical consequences of THA are discussed based on the current literature.

22q11.2 Microduplication: An Enigmatic Genetic Disorder

Microduplication of 22q11.2 involves having an extra copy at position q11.2 on chromosome 22. Very few cases have been reported but the real incidence may be higher as the absence of obvious clinical signs makes diagnosis difficult. In the cases that are diagnosed, the phenotype is extremely variable. We describe a case of severe micrognathia, cleft palate, and Pierre-Robin sequence. A prenatal ultrasound showed severe micrognathia and subsequent microarray done on amniocentesis revealed the microduplication of 22q11.2, which was confirmed postnatally. Although micrognathia has often been detected in this microduplication, the constellation of these findings has not been previously described.

Thyroid Hemiagenesis: Incidence, Clinical Significance, and Genetic Background

CONTEXT

Thyroid hemiagenesis (THA) constitutes a rare, congenital disorder that is characterized by an absence of one thyroid lobe. Because the pathogenesis and clinical significance of this malformation remain undefined, specific clinical recommendations are lacking, especially for asymptomatic cases.

EVIDENCE ACQUISITION

The PubMed database was searched (years 1970 to 2017), and the following terms were used to retrieve the results: "thyroid hemiagenesis," "thyroid hemiaplasia," "one thyroid lobe agenesis," and "one thyroid lobe aplasia." Subsequently, reference sections of the retrieved articles were searched.

EVIDENCE SYNTHESIS

There is a noticeable susceptibility of subjects with THA to develop additional thyroid and nonthyroidal pathologies. In pathogenesis of concomitant thyroid pathologies, a chronic elevation in thyroid-stimulating hormone values may play an important role. Thus far, genetic studies failed to find a common genetic background of the anomaly, and the potential underlying cause was identified in a minority of the cases.

CONCLUSIONS

Patients with THA are prone to develop additional thyroid pathologies and theoretically might benefit from l-thyroxine treatment to lower the thyrotropin levels to those observed in the normal population. However, further research should be done to ascertain whether such intervention early in life would prevent development of associated thyroid conditions. At least, increased vigilance should be maintained to reveal all of the concomitant disorders as soon as possible during follow-up examinations. Application of high-throughput technologies enabling a genome-wide search for novel factors involved in thyroid embryogenesis might be the next step to expand the knowledge on THA pathogenesis.

22q11.2 microduplication syndrome with associated esophageal atresia/tracheo-esophageal fistula and vascular ring

This case report describes a patient with a 22q11.2 duplication. His features, which include VACTERL association with an esophageal atresia/tracheo‐esophageal fistula and a vascular ring, expand the previously described phenotype for this duplication.

Identification of Proximal and Distal 22q11.2 Microduplications among Patients with Cleft Lip and/or Palate: A Novel Inherited Atypical 0.6 Mb Duplication

Misalignments of low-copy repeats (LCRs) located in chromosome 22, particularly band 22q11.2, predispose to rearrangements. A variety of phenotypic features are associated with 22q11.2 microduplication syndrome which makes it challenging for the genetic counselors to recommend appropriate genetic assessment and counseling for the patients. In this study, multiplex ligation probe dependent amplification (MLPA) analysis was performed on 378 patients with cleft lip and/or palate to characterize rearrangements in patients suspected of 22q11.2 microduplication and microdeletion syndromes. Of 378 cases, 15 were diagnosed with a microdeletion with various sizes and 3 with duplications. For the first time in this study an atypical 0.6 Mb duplication is reported. Illustration of the phenotypes associated with the microduplications increases the knowledge of phenotypes reported in the literature.

Identification of deletions in children with congenital hypothyroidism and thyroid dysgenesis with the use of multiplex ligation-dependent probe amplification

INTRODUCTION

Thyroid dysgenesis (TD) is the most common cause of congenital hypothyroidism (CH). Important genetic factors possibly contributing to TD etiologies include mutations of thyroid transcription factors and TSHR-encoding genes.

OBJECTIVE

Our objective was to determine multiplex ligation-dependent probe amplification (MLPA) utility in detecting the copy number changes in patients with CH and TD.

METHODS

The study included 45 children from southeastern Poland selected via already established neonatal screening for CH. Genomic DNA was extracted from peripheral blood samples and used in MLPA analysis. Genetic variations were analyzed within selected fragments of the PAX8, FOXE1, NKX2-1, thyroid stimulating hormone receptor (TSHR), and TPO genes.

RESULTS

Three heterozygous deletion types in probe hybridization regions were identified for the following genes: PAX8 (exon 7), TSHR (exon 2), and FOXE1 (exon 1). Monoallelic deletions were identified in 5/45 TD subjects.

CONCLUSIONS

MLPA is a useful tool for copy number changes detection and might both improve and expand genetic analysis for CH and TD.