Prenatal diagnosis of familial 22q11.2 deletion syndrome in a pregnancy with concomitant cardiac and urinary tract abnormalities in the fetus and the mother

Moesin contributes to heat shock gene response through direct binding to the Med15 subunit of the Mediator complex in the nucleus

The members of the evolutionary conserved actin-binding Ezrin, Radixin and Moesin (ERM) protein family are involved in numerous key cellular processes in the cytoplasm. In the last decades, ERM proteins, like actin and other cytoskeletal components, have also been shown to be functional components of the nucleus; however, the molecular mechanism behind their nuclear activities remained unclear. Therefore, our primary aim was to identify the nuclear protein interactome of the single Drosophila ERM protein, Moesin. We demonstrate that Moesin directly interacts with the Mediator complex through direct binding to its Med15 subunit, and the presence of Moesin at the regulatory regions of the Hsp70Ab heat shock gene was found to be Med15-dependent. Both Moesin and Med15 bind to heat shock factor (Hsf), and they are required for proper Hsp gene expression under physiological conditions. Moreover, we confirmed that Moesin, Med15 and Hsf are able to bind the monomeric form of actin and together they form a complex in the nucleus. These results elucidate a mechanism by which ERMs function within the nucleus. Finally, we present the direct interaction of the human orthologues of Drosophila Moesin and Med15, which highlights the evolutionary significance of our finding.

DiGeorge Syndrome Diagnosed at Age 38: Challenges in Low-resource Settings and Implications of a Missed Diagnosis

22q11.2 deletion syndrome (22.q11.2 DS) is a genetic syndrome resulting from a microdeletion on chromosome 22. It has a diverse array of manifestations, and most cases are diagnosed early in childhood. We present the case of a 38-year-old female born in a developing country who presented to our clinic to establish care for a history of primary hypothyroidism. She was clinically and biochemically euthyroid on thyroid supplementation. She was also noted to have hypocalcemia in the setting of low PTH, for which the patient was previously prescribed calcitriol. Given a history of cleft palate, abnormal facial features, mild recurrent sinopulmonary infections, and her endocrine history (including short stature with height in the 6th percentile), genetic testing was obtained. She was diagnosed with a heterozygous whole gene deletion of the TBX1 gene. Additional genetic evaluation demonstrated a 2.6-Mb microdeleted segment of the 22a11.2 region encompassing 62 genes. The patient was referred to cardiology for evaluation of cardiac involvement given a history of tachyarrhythmia. This case highlights challenges in diagnosis and the implications of a delayed diagnosis of 22.q11.2 DS.

Late maternal diagnosis of DiGeorge syndrome with congenital hypoparathyroidism following antenatal detection of the same 22q11.2 microdeletion syndrome in the fetus

Genetic causes of hypocalcaemia can be overlooked in patients who present without apparent syndromic features. One relatively common but under-recognised genetic disorder is DiGeorge syndrome, which is often diagnosed in childhood but rarely in adulthood. Its enigmatic diagnosis can be attributed to its broad heterogeneous clinical presentation, such as the absence of cardiac abnormalities with only subtly abnormal facies. The presence of hypoparathyroidism-related hypocalcaemia may be the first early sign. We describe a young female adult with childhood-onset hypocalcaemia who was diagnosed with DiGeorge syndrome during her pregnancy when the fetus was found to have the same condition on antenatal screening and autopsy. This case reminds clinicians to consider the genetic causes of hypoparathyroidism-induced hypocalcaemia early on in childhood, while acknowledging the possibility of a late diagnosis in adulthood. We also highlight the risks of severe hypocalcaemia in pregnancy and outline a systematic approach to the evaluation of chronic hypocalcaemia.