Non-invasive prenatal diagnosis of multiple endocrine neoplasia type 2A using COLD-PCR combined with HRM genotyping analysis from maternal serum

Prenatal genetic diagnosis of monogenic diseases

Prenatal genetic diagnosis of monogenic diseases is a process involving the use of a variety of molecular techniques for the molecular characterization of a potential monogenic disease in the fetus during pregnancy. Prenatal genetic diagnosis can be performed through invasive and non-invasive methods. A distinction must be made between "NIPD" (non-invasive prenatal diagnosis), which is considered to be diagnostic, from "NIPT" (non-invasive prenatal test), which is a screening test that requires subsequent confirmation by invasive methods. The different techniques currently available aim at detecting either, previously characterized pathogenic mutations in the family, the risk haplotype associated with the familial mutation, or potential pathogenic mutation(s) in a gene associated with a diagnostic suspicion. An overview is provided of relevant aspects of prenatal genetic diagnosis of monogenic diseases. The objective of this paper is to describe the main molecular techniques currently available and used in clinical practice. A description is provided of the indications, limitations and analytical recommendations regarding these techniques, and the standards governing genetic counseling. Continuous rapid advances in the clinical applications of genomics have provided increased access to comprehensive molecular characterization. Laboratories are struggling to keep in pace with technology developments.

Detection of Paternal IVS-II-1 (G>A) (HBB: c.315+1G>A) Mutation in Cell-Free Fetal DNA Using COLD-PCR assay

Standardization of noninvasive prenatal diagnosis (PND) method that can identify common mutations in the population is of great value. The purpose of this study was to find the paternal HBB gene IVS-II-1 (G>A) (HBB: c.315+1G>A) mutation in maternal plasma cell-free DNA using the co-amplification at lower denaturation temperature-polymerase chain reaction (COLD-PCR) method. We designed simulated circulating free DNA (cfDNA) in maternal plasma to optimize the COLD-PCR assay. Peripheral blood samples were collected from normal and IVS-II-1 heterozygous individuals as well as five heterozygous pregnant women whose husbands were carriers of IVS-II-1. The cfDNA was extracted from the plasma and subjected to optimized COLD-PCR followed by Sanger sequencing. The optimized protocol was tested on simulated cfDNA samples with proportions of 8.0, 6.0, 4.0 and 2.0%, and the results showed that the COLD-PCR is informative on samples containing 8.0% mutant alleles and above. The patients were undergoing invasive PND procedures via chorionic villi sampling (CVS) as scheduled at the 12th week of gestation. Paternal IVS-II-1 was detected in cfDNA samples of three patients who were in complete concordance with the outcome of CVS. Despite the limitations of the COLD-PCR method in noninvasive PND, it can be considered as a cost-effective screening option. The use of this approach for screening at-risk patients can prevent unnecessary invasive procedures identifying common mutations in high-prevalence diseases.

Thyroid nodules and cancer during pregnancy, post-partum and preconception planning: Addressing the uncertainties and challenges

Thyroid nodules and thyroid cancer have become increasingly common worldwide. When discovered during pregnancy, they pose unique diagnostic and therapeutic challenges for both the treating physician and the patient. The benefits of treatment should be carefully weighed against risks that may adversely impact maternal and fetal health. In this review, we present current knowledge and controversies surrounding the management of thyroid nodules and thyroid cancer in pregnancy, in the post-partum period and during preconception planning.

5P Strategies for Management of Multiple Endocrine Neoplasia Type 2: A Paradigm of Precision Medicine

Multiple endocrine neoplasia type 2 (MEN2) is a neuroendocrine cancer syndrome characterized by medullary thyroid carcinoma, in combination or not with pheochromocytoma, hyperparathyroidism, and extra-endocrine features. MEN2 syndrome includes two clinically distinct forms subtyped as MEN2A and MEN2B. Nearly all MEN2 cases are caused by germline mutations of the RET proto-oncogene. In this review, we propose "5P" strategies for management of MEN2: prevention, prediction, personalization, psychological support, and participation, which could effectively improve clinical outcomes of patients. Based on RET mutations, MEN2 could be prevented through prenatal diagnosis or preimplantation genetic testing. Identification of pathogenic mutations in RET can enable early diagnosis of MEN2. Combining RET mutation testing with measurement of serum calcitonin, plasma or urinary metanephrine/normetanephrine, and serum parathyroid hormone levels could allow risk stratification and accurately prediction of MEN2 progression, thus facilitating implementation of personalized precision treatments to increase disease-free survival and overall survival. Furthermore, increased awareness of MEN2 is needed, which requires participation of physicians, patients, family members, and related organizations. Psychological support is also important for patients with MEN2 to promote comprehensive management of MEN2 symptoms. The "5P" strategies for management of MEN2 represent a typical clinical example of precision medicine. These strategies could effectively improve the health of MEN2 patient, and avoid adverse outcomes, including death and major morbidity, from MEN2.

Optimal non-invasive diagnosis of fetal achondroplasia combining ultrasonography with circulating cell-free fetal DNA analysis

OBJECTIVES

To assess the performance of non-invasive prenatal testing (NIPT) for achondroplasia using high-resolution melting (HRM) analysis, and to propose an optimal diagnostic strategy combining ultrasound examination and cell-free fetal DNA (cffDNA) analysis.

METHODS

In this prospective multicenter study, cffDNA was extracted from blood of pregnant women at risk for fetal achondroplasia (owing to paternal achondroplasia, previous affected child or suspected rhizomelic shortening) and of pregnant low-risk controls. The presence of either one of the two main fibroblast growth factor receptor 3 gene (FGFR3) mutations was determined using HRM combined with confirmation by SNaPshot minisequencing. Results were compared with phenotypes obtained using three-dimensional computed tomography or postnatal examination, and/or molecular diagnosis by an invasive procedure. Fetal biometry (head circumference and femur length) was analyzed in order to develop a strategy in which cffDNA analysis for diagnosis of achondroplasia is offered only in selected cases.

RESULTS

Eighty-six blood samples from women at risk for fetal achondroplasia and 65 from controls were collected. The overall sensitivity and specificity of NIPT were 1.00 (95% CI, 0.87-1.00) and 1.00 (95% CI, 0.96-1.00), respectively. Critical reduction in femur length of affected fetuses could be observed from 26 weeks' gestation.

CONCLUSIONS

HRM combined with SNaPshot minisequencing is a reliable method for NIPT for achondroplasia. Its implementation in routine clinical care combined with ultrasonography is an efficient strategy for the non-invasive diagnosis of achondroplasia. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

COLD-PCR Technologies in the Area of Personalized Medicine: Methodology and Applications

Somatic mutations bear great promise for use as biomarkers for personalized medicine, but are often present only in low abundance in biological material and are therefore difficult to detect. Many assays for mutation analysis in cancer-related genes (hotspots) have been developed to improve diagnosis, prognosis, prediction of drug resistance, and monitoring of the response to treatment. Two major approaches have been developed: mutation-specific amplification methods and methods that enrich and detect mutations without prior knowledge on the exact location and identity of the mutation. CO-amplification at Lower Denaturation temperature Polymerase Chain Reaction (COLD-PCR) methods such as full-, fast-, ice- (improved and complete enrichment), enhanced-ice, and temperature-tolerant COLD-PCR make use of a critical temperature in the polymerase chain reaction to selectively denature wild-type-mutant heteroduplexes, allowing the enrichment of rare mutations. Mutations can subsequently be identified using a variety of laboratory technologies such as high-resolution melting, digital polymerase chain reaction, pyrosequencing, Sanger sequencing, or next-generation sequencing. COLD-PCR methods are sensitive, specific, and accurate if appropriately optimized and have a short time to results. A large variety of clinical samples (tumor DNA, circulating cell-free DNA, circulating cell-free fetal DNA, and circulating tumor cells) have been studied using COLD-PCR in many different applications including the detection of genetic changes in cancer and infectious diseases, non-invasive prenatal diagnosis, detection of microorganisms, or DNA methylation analysis. In this review, we describe in detail the different COLD-PCR approaches, highlighting their specificities, advantages, and inconveniences and demonstrating their use in different fields of biological and biomedical research.

Revised American Thyroid Association guidelines for the management of medullary thyroid carcinoma

INTRODUCTION

The American Thyroid Association appointed a Task Force of experts to revise the original Medullary Thyroid Carcinoma: Management Guidelines of the American Thyroid Association.

METHODS

The Task Force identified relevant articles using a systematic PubMed search, supplemented with additional published materials, and then created evidence-based recommendations, which were set in categories using criteria adapted from the United States Preventive Services Task Force Agency for Healthcare Research and Quality. The original guidelines provided abundant source material and an excellent organizational structure that served as the basis for the current revised document.

RESULTS

The revised guidelines are focused primarily on the diagnosis and treatment of patients with sporadic medullary thyroid carcinoma (MTC) and hereditary MTC.

CONCLUSIONS

The Task Force developed 67 evidence-based recommendations to assist clinicians in the care of patients with MTC. The Task Force considers the recommendations to represent current, rational, and optimal medical practice.

Application of coamplification at lower denaturation temperature-PCR sequencing for early detection of antiviral drug resistance mutations of hepatitis B virus

Nucleoside/nucleotide analogue for the treatment of chronic hepatitis B virus (HBV) infection is hampered by the emergence of drug resistance mutations. Conventional PCR sequencing cannot detect minor variants of <20%. We developed a modified co-amplification at lower denaturation temperature-PCR (COLD-PCR) method for the detection of HBV minority drug resistance mutations. The critical denaturation temperature for COLD-PCR was determined to be 78°C. Sensitivity of COLD-PCR sequencing was determined using serially diluted plasmids containing mixed proportions of HBV reverse transcriptase (rt) wild-type and mutant sequences. Conventional PCR sequencing detected mutations only if they existed in ≥25%, whereas COLD-PCR sequencing detected mutations when they existed in 5 to 10% of the viral population. The performance of COLD-PCR was compared to conventional PCR sequencing and a line probe assay (LiPA) using 215 samples obtained from 136 lamivudine- or telbivudine-treated patients with virological breakthrough. Among these 215 samples, drug resistance mutations were detected in 155 (72%), 148 (69%), and 113 samples (53%) by LiPA, COLD-PCR, and conventional PCR sequencing, respectively. Nineteen (9%) samples had mutations detectable by COLD-PCR but not LiPA, while 26 (12%) samples had mutations detectable by LiPA but not COLD-PCR, indicating both methods were comparable (P = 0.371). COLD-PCR was more sensitive than conventional PCR sequencing. Thirty-five (16%) samples had mutations detectable by COLD-PCR but not conventional PCR sequencing, while none had mutations detected by conventional PCR sequencing but not COLD-PCR (P < 0.0001). COLD-PCR sequencing is a simple method which is comparable to LiPA and superior to conventional PCR sequencing in detecting minor lamivudine/telbivudine resistance mutations.

Diagnosis and surgical treatment of multiple endocrine neoplasia type 2A

BACKGROUND

This study aims to introduce the diagnosis and surgical treatment of the rare disease multiple endocrine neoplasia type 2A (MEN 2A).

METHODS

Thirteen cases of MEN 2A were diagnosed as medullary thyroid carcinoma (MTC) and pheochromocytoma by biochemical tests and imaging examination. They were treated by bilateral adrenal tumor excision or laparoscopic surgery.

RESULTS

Nine patients were treated by bilateral adrenal tumor excision and the remaining four were treated by laparoscopic surgery for pheochromocytoma. Ten patients were treated by total thyroidectomy and bilateral lymph nodes dissection and the remaining three were treated by unilateral thyroidectomy for MTC. Up to now, three patients have died of MTC distant metastasis.

CONCLUSIONS

We confirmed that MEN 2A can be diagnosed by biochemical tests and imaging examination when genetic testing is not available. Surgical excision is the predominant way to treat MEN 2A; pheochromocytoma should be excised at first when pheochromocytoma and MTC occur simultaneously.