The genetic diagnosis of rare endocrine disorders of sex development and maturation: a survey among Endo-ERN centres.

Differences of sex development and maturation (SDM) represent a heterogeneous puzzle of rare conditions with a large genetic component whose management and treatment could be improved by an accurate classification of underlying molecular conditions, and next-generation sequencing (NGS) should represent the most appropriate approach. Therefore, we conducted a survey dedicated to the use and potential outcomes of NGS for SDM disorders diagnosis among the 53 health care providers (HCP) of the European Reference Network for rare endocrine conditions. The response rate was 49% with a total of 26 HCPs from 13 countries. All HCPs, except 1, performed NGS investigations for SDM disorders on 6720 patients, 3764 (56%) with differences of sex development (DSD), including 811 unexplained primary ovarian insufficiency, and 2956 (44%) with congenital hypogonadotropic hypogonadism (CHH). The approaches varied from targeted analysis of custom gene panels (range: 11-490 genes) in 81.5% of cases or whole exome sequencing with the extraction of a virtual panel in the remaining cases. These analyses were performed for diagnostic purposes in 21 HCPs, supported by the National Health Systems in 16 cases. The likelihood of finding a variant ranged between 7 and 60%, mainly depending upon the number of analysed genes or criteria used for reporting, most HCPs also reporting variants of uncertain significance. These data illustrate the status of genetic diagnosis of DSD and CHH across Europe. In most countries, these analyses are performed for diagnostic purposes, yielding highly variable results, thus suggesting the need for harmonization and general improvements of NGS approaches.

Diagnosis and clinical relevance of co-inheritance of haemoglobin D-Punjab/ß+-thalassemia traits in an immigrant Afghan family.

We report on a Pashtun family affected by haemoglobin D-Punjab/ß+-thalassemia to increase the awareness of the increasing prevalence of haemoglobinopathies among primary care physicians. We highlight the diagnostic approach of these conditions and the benefits of genetic counselling.

Heterogeneous colonic content: A prenatal sonographic manifestation of lysinuric protein intolerance.

We report a fetus with heterogeneous colonic content, an isolated sonographic prenatal sign of lysinuric protein intolerance, a very rare metabolic disease. Familial genetic enquiries confirmed heterozygote mutation in the implicated gene in parents. The prenatal diagnosis led to neonatal dietary adaptation and avoided acute complications.

Development by Genetic Immunization of Monovalent Antibodies Against Human Vasoactive Intestinal Peptide Receptor 1 (VPAC1), New Innovative, and Versatile Tools to Study VPAC1 Receptor Function.

Multi-membrane spanning proteins, such as G protein-coupled receptors (GPCRs) and ion channels, are extremely difficult to purify as native proteins. Consequently, the generation of antibodies that recognize the native conformation can be challenging. By combining genetic immunization, phage display, and biopanning, we identified a panel of monovalent antibodies (nanobodies) targeting the vasoactive intestinal peptide receptor 1 (VPAC1) receptor. The nine unique nanobodies that were classified into four different families based on their CDR3 amino acid sequence and length, were highly specific for the human receptor and bind VPAC1 with moderate affinity. They all recognize a similar epitope localized in the extracellular N-terminal domain of the receptor and distinct from the orthosteric binding site. In agreement with binding studies, which showed that the nanobodies did not interfere with VIP binding, all nanobodies were devoid of any functional properties. However, we observed that the binding of two nanobodies was slightly increased in the presence of VPAC1 agonists [vasoactive intestinal polypeptide (VIP) and pituitary adenylate cyclase-activating polypeptide-27 (PACAP-27)], but decreased in the presence of VPAC1 antagonist. As no evidence of allosteric activity was seen in VIP binding studies nor in functional assays, it is, therefore, possible that the two nanobodies may behave as very weak allosteric modulators of VPAC1, detectable only in some sensitive settings, but not in others. We demonstrated that the fluorescently labeled nanobodies detect VPAC1 on the surface of human leukocytes as efficiently as a reference mouse monoclonal antibody. We also developed a protocol allowing efficient detection of VPAC1 by immunohistochemistry in paraffin-embedded human gastrointestinal tissue sections. Thus, these nanobodies constitute new original tools to further investigate the role of VPAC1 in physiological and pathological conditions.

Development by Genetic Immunization of Monovalent Antibodies (Nanobodies) Behaving as Antagonists of the Human ChemR23 Receptor.

The generation of Abs that recognize the native conformation of G protein-coupled receptors can be a challenging task because, like most multimembrane-spanning proteins, they are extremely difficult to purify as native protein. By combining genetic immunization, phage display, and biopanning, we identified two functional monovalent Abs (nanobodies) targeting ChemR23. The two nanobodies (CA4910 and CA5183) were highly specific for the human receptor and bind ChemR23 with moderate affinity. Binding studies also showed that they share a common binding site that overlaps with that of chemerin, the natural ligand of ChemR23. Consistent with these results, we found that the nanobodies were able to antagonize chemerin-induced intracellular calcium increase. The inhibition was partial when chemerin was used as agonist and complete when the chemerin(149-157) nonapeptide was used as agonist. Engineering of a bivalent CA4910 nanobody resulted in a relatively modest increase in affinity but a marked enhancement of efficacy as an antagonist of chemerin induced intracellular calcium mobilization and a much higher potency against the chemerin(149-157) nonapeptide-induced response. We also demonstrated that the fluorescently labeled nanobodies detect ChemR23 on the surface of human primary cell populations as efficiently as a reference mouse mAb and that the bivalent CA4910 nanobody behaves as an efficient antagonist of chemerin-induced chemotaxis of human primary cells. Thus, these nanobodies constitute new tools to study the role of the chemerin/ChemR23 system in physiological and pathological conditions.