Identification of Novel Variants in MEN1: A Study Conducted with Four Multiple Endocrine Neoplasia Type 1 Patients

Abstract

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant inherited endocrine tumor syndrome caused by inactivating variants of the MEN1 gene. The aim of this study is to explore the clinical and genetic characteristics of four MEN1 patients. We isolated genomic deoxyribonucleic acid from lymphocytes, parathyroid, and thymic tumoral tissue specimens from the MEN1 patients. All exons of the MEN1 and CDNK1B genes and adjacent exon-intron sequences were amplified by polymerase chain reaction and subsequently sequenced. Further, the splice alterations were studied by sequencing the amplified RT-PCR products for MEN1 cDNA. We identified four heterozygous MEN1 germline variants: c.564delC, c.1268G>A, IVS5+5delG, and c.1546_1547insC. Both c.564delC and IVS5+5delG were novel variants. The impact of the MEN1 splice variant, IVS5+5delG, was evaluated using bioinformatics and in vitro analyses. The analyses indicated that this variant resulted in skipping of the neighboring exon and was disease-causing. Two novel somatic variants, c.249_252delGTCT and c.313_314insC, were found. Additionally, loss of heterozygosity (LOH) for the MEN1 locus (IVS5+5delG and c.564delC) was found in tumor tissue samples from the MEN1 patients, consistent with Knudson’s two-hit mechanism. We identified four MEN1 germline variants and two novel somatic variants. Early recognition of the phenotype coupled with variant screening of the MEN1 gene is the key to diagnosing and treating MEN1 effectively at an early stage.

Clinical and functional analyses of the novel STAR c.558C>A in a patient with classic lipoid congenital adrenal hyperplasia

“…The DNA was cut into a length of 200–300 bp on the Bioruptor UCD-200 (Diagenode), diluted, loaded, and sequenced on the HiSeq2500 platform (Illumina, San Diego, CA). Exome data processing and variant annotation were performed as previously described ( Hu et al, 2020 ; Zhang et al, 2020 ; Guan et al, 2022 ), focusing on LCAH pathogenic genes. Mutations are rare events with a frequency of less than 1% in 1,000 genomes ( http://browser.1000genomes.org ), Exome Aggregation Consortium (ExAC, http://exac.broadinstitute.org/ ), and Genome Aggregation Database (gnomAD, http://gnomad.broadinstitute.org/ ).…”

Different cell compositions and a novel somatic KCNJ5 variant found in a patient with bilateral adrenocortical adenomas secreting aldosterone and cortisol

“…The samples were diluted, loaded, and sequenced on the HiSeq2500 platform (Illumina, San Diego, CA). Further, exome data processing and variant annotation were performed as described in a previous study ( 17 ). The variants were interpreted according to the standards of the American College of Medical Genetics (ACMG) and categorized as follows: pathogenic, likely pathogenic, variants of uncertain significance, likely benign, or benign.…”

Genetic and Functional Analyses of the Novel KLF11 Pro193Thr Variant in a Three-Generation Family with MODY7

“…Samples were diluted, loaded, and sequenced on the HiSeq2500 platform (Illumina, San Diego, CA, USA). Exome data processing, and variant annotation were performed as previously described 20 21 . In this study, we focused on the causative genes for monogenic diabetes.…”