Context: Congenital hypopituitarism is a genetically heterogeneous condition. Whole exome sequencing (WES) is a promising approach for molecular diagnosis of patients with this condition. Objectives: To conduct WES in a patient with congenital hypopituitarism born to consanguineous parents, CDH2 screening in a cohort of patients with congenital hypopituitarism, and functional testing of a novel CDH2 variant. Design: Genomic DNA from a proband and her consanguineous parents was analyzed by WES. Copy number variants were evaluated. The genetic variants were filtered for population frequency (ExAC, 1000 genomes, gnomAD and ABraOM), in silico prediction of pathogenicity, and gene expression in pituitary and/or hypothalamus. Genomic DNA from 145 patients was screened for CDH2 by Sanger sequencing. Results: One female patient with deficiencies in GH, TSH, ACTH, LH, and FSH and ectopic posterior pituitary gland contained a rare homozygous c.865G>A (p.Val289Ile) variant in CDH2. To determine whether the p.Val289Ile variant in CDH2 affects cell adhesion properties, we stably transfected L1 fibroblast lines, labeled the cells with lipophilic dyes, and quantified aggregation. Large aggregates formed in cells expressing wild type CDH2, but aggregation was impaired in cells transfected with variant CDH2 or non-transfected. Conclusion: A homozygous CDH2 allelic variant was found in 1 hypopituitarism patient, and the variant impaired cell aggregation function in vitro. No disease-causing variants were found in 145 other patients screened for CDH2 variants. Thus, CDH2 is a candidate gene for hypopituitarism that needs to be tested in different populations.
Introduction: Hypopituitarism is defined as a deficiency of one or more pituitary hormones. Pathogenic allelic variants in genes implicated in pituitary development were associated in 15% of the patients with congenital hypopituitarism (CH). To improve the molecular diagnosis we performed whole exome sequencing of ten patients born from consanguineous parents with CH. One patient with GH, TSH, ACTH and LH/FSH deficiencies presented an allelic variant c.865G>A, p.V289I in CDH2 gene (exon 7) in homozygous state that was absent in populational databanks. CDH2 produces an N-cadherin protein implicated in cellular adhesion and is responsible for epithelial-mesenchymal transition during pituitary development and differentiation. Aim: To analyze the CDH2 gene in a cohort of unrelated patients with CH. Methods: We selected 143 patients with CH from a single Brazilian center. Genomic DNA, extracted by salting out technique, was submitted to PCR amplification of 15 coding regions, except CG rich exon 1, of the CDH2 gene followed by the Sanger sequencing. Rare allelic variant frequency (MAF<1%) was searched in the populational data bank (ExAC, gnomAD, ABraom). Bioinformatic sites (Human Splicing Finder, Polyphen2, Mutation Taster and Mutation assessor) were used to look for deleterious effects. Results: Three allelic variants were found in this cohort. The allelic variant CDH2 (c.865G>A, p.V289I) was found in heterozygous state in a male patient with short stature diagnosed with GH and TSH deficiencies at the age of 11 that evolved with LH/FSH and ACTH deficiencies. Family segregation showed 3 among 11 normal siblings heterozygous carriers. This variant is rare, in heterozygous state, in populational data bank and it was predicted as deleterious or possibly harmful. The allelic variant c.1202C> A (p.A401D), in exon 9, was found in heterozygous state in a female patient with isolated GH deficiency and intellectual disability. The variant was absent in the databases and predicted as deleterious or disease-causing. The variant was absent in the mother and stepsister and the father was not available for testing. The c.1430_1431delCCinsTG allelic variant (p.P477L) was found in heterozygous state in a patient with septo-optic dysplasia, GH, TSH and ACTH deficiencies. It was absent in the databases and was predicted as deleterious or disease causing. The Human Splicing Finder predicted exonic splicing enhancer breakdown leading to the loss of 93 nucleotides. Normal mother is heterozygous carrier suggesting incomplete penetrance. Conclusion: Heterozygous variants in CDH2 were found in 2% of a cohort of Brazilian patients with congenital hypopituitarism and none in homozygous or compound heterozygous state. Further CDH2 analyses in unrelated patients from different ethnic backgrounds are needed to establish the role CDH2 variants in the etiology of congenital hypopituitarism.
Introduction: Despite the use of robust techniques for diagnosis, such as arrays and large-scale sequencing of patients with differences of sex development (DSD), the etiology of a great number of DSD patients remains unclear. Investigation of alternative signaling pathways and epigenetic factors is scarce in 46,XY DSD patients. The ZEB proteins have been related to the occurrence of hypospadias in humans, a feature often observed in the atypical genitalia of patients with 46,XY DSD. Additionally, miR-200c has been reported to regulate ZEB. Objective: To evaluate the expression of miR-200c in plasma samples of 46,XY DSD patients with unknown etiology. Methods: Plasma miR-200c of six adult 46,XY DSD patients with unknown etiology (age 18-33, mean 19±8) and 15 adult male controls (age 18-55, mean 29±10 yo) were analyzed. External Masculinization Score (EMS) was used to describe the undervirilization degree of patients’ external genitalia and to classify them in two groups with low EMS (LEMS: 0-4.9 points) and high EMS (HEMS: 5-10 points). All patients presented atypical genitalia with hypospadias. miR-200c was selected based on its targeting to ZEB1 and in silico analysis; miR-23a was used as internal normalization control. RNA was extracted from plasma samples with Magmax Mirvana Total RNA isolation kit. cDNA was synthesized using TaqMan Advanced miRNA cDNA Synthesis Kit and qPCR was performed using TaqMan Advanced miRNA. The data analysis of qPCR results of patients, of each individualized patient and also the EMS groups were compared with the control group by statistical test. Results: LEMS group presented lower expression values of miR-200c when compared to HEMS group (P=0.0001) and control group (p=0.0009), but no difference was observed when comparing HEMS group and controls, the two patients with lower miR-200c expression presented the lowest EMS (EMS- 3 and 3.5). Altogether, patients presented lower values of miR-200c, although not significantly (p=0.09). Discussion: These findings corroborate with previous literature data correlating miR200-c, ZEB1 and hypospadias. The regulatory loop of miR-200c/Zeb1 was previously demonstrated in rats with hypospadias, confirming that low expression of miR-200c induce a higher Zeb1 expression. The ZEB1 upregulation in penile tissue is positively correlated with the severity of hypospadias in animal models and humans. In the present study, 46,XY DSD patients with severe genital undervirilization had lower miR-200c expression in plasma. Conclusion: Plasma miRNA expression patterns may be a new strategy research in 46,XY DSD, contributing for understanding the processes involved in the external genitalia development.
Introduction: The CDH2 gene encodes a transmembrane protein responsible for calcium-dependent cell-cell adhesion that participates in the process of embrionic development. Neural development is achieved by neuronal neurulation, migration and differentiation, as well as axon growth and synapse formation. During pituitary development, CDH2 was associated to the epithelium-to-mesenchymal transition, with cell migration from the marginal zone to the anterior pituitary gland, followed by terminal differentiation. Thus, a dysfunction in n-cadherins disrupts the architecture of the neural tube, cortical architecture of the embryonic brain and pituitary development. In a previous study in our laboratory, a patient was diagnosed with a homozygous variant located in the N-terminal region of CDH2 (p.Val289IIe) that culminated in congenital hypopituitarism and pituitary hypoplasia. Together, these observations indicate that cadherins, especially N-cadherin, play an indispensable role in the organization of neuroepithelial layers. Zebrafish has been widely used as a model for studies of gene functionality, as it has 70% genetic homology to humans, besides being a small animal with rapid development. Our goal was to generate a zebrafish knockout for the CDH2 gene, using CRISPR Cas9 genomic edition to study its importance during development and analyze this gene in patients with characteristics similar to those observed in zebrafish. Material and methods: Three guides were drawn for the CDH2 gene using crispor program. sgRNA, produced by in vitro transcription, and Cas9 protein were injected into one cell stage. All developmental parameters were observed under a microscope up to 96 hours post fertilization (hpf). Mortality rate were calculated at 24, 48, 72 and 96 hpf. The embryos were genotyped to confirm the deleterious allelic variant. CDH2 coding region was evaluated in 3 female siblings, born from consanguineous parents, presenting micro/anophtalmia and short stature. Exons 2 to 16 were sequenced by the Sanger method. Results: 352 eggs were injected and several deformities such as absence of somites, cardiac edema, spinal curvature, cranial malformation and microphthalmia or total absence of eyes were observed. The mortality rates were 26%, 31%, 40% and 62% at 24, 48, 72 and 96 hpf, respectively. The Sanger sequencing from DNA extracted from the whole animal presented deleterious effect classified as insertions, deletions and missense changes. No deleterious allelic variant was observed in the 15 analyzed exons in the 3 patients. Conclusion: The CDH2 gene is important for neurodevelopment and eyes formation in the zebrafish although pathogenic allelic variants in this gene was not found in the studied patients with short stature and eye abnormalities.
Introduction: Hypopituitarism is defined as the deficiency of one or more pituitary hormones and can occur due to pathogenic allelic variants in transcription factors involved in pituitary development. PROP1 gene is responsible for progenitor cell migration from the marginal zone to the anterior lobe, and its terminal differentiation into corticotropes and gonadotropes cell lines besides somatotropes, lactotropes and thyrotropes due to POU1F1 (also known as PIT1) activation. In humans, mutations in the PROP1 gene are the most common cause of congenital hypopituitarism with GH, TSH, LH/FSH, and progressive ACTH deficiencies. A dwarf phenotype with short stature, pituitary hormone deficiency, and infertility has been described in humans and Ames mice lineage harboring mutations in the PROP1/Prop1 gene. Another valuable animal model used in basic research is the zebrafish (Danio rerio) due to a high homology in neuroendocrine functioning. To test the potential of this model, in our previous study, a 32bp insertion carrying a stop codon was directed into the second exon of prop1 with CRISPR/Cas9, establishing a homozygous mutant strain (prop1mut). Objective: To characterize the phenotype and expression patterns of transcription factors and hormones in the zebrafish prop1mut lineage. Methods: prop1, pit1, and gh1 mRNA levels were analyzed during embryonic development at 24 and 72 hours post-fertilization (hpf). RNA from 30 pooled embryos was extracted using DirectZol RNA Miniprep. cDNA was synthesized from 1ug of total RNA using High-Capacity cDNA Reverse Transcription Kit and qPCR was performed using SYBR Green PCR Master Mix. Gene expression was normalized to ef1a and the prop1mut group was compared with the control wild type group (WT). Animals were kept in the tanks at a density of 15 animals/liter and images were acquired at 13 and 20 days post fertilization (dpf) after brief anesthetization using a stereomicroscope and measured in ImageJ software to determine the larval standard length from nose to the end of the spinal cord. Results: At 24 and 72hpf, prop1mut embryos expressed the altered prop1 mRNA at similar levels to the prop1 expression observed in WT. Lower pit1 expression in prop1mut embryos was observed at both periods (p<0.01). Albeit in low levels, similar gh1 expression was observed in both lineages at 24hpf, and prop1mut embryos presented lower gh1 expression at 72hpf (p<0.001). prop1mut larvae presented a significant decrease in size at 13dpf (p<0.001) but not at 20dpf. Conclusion: In this study, the prop1mut zebrafish model exhibited a dwarf phenotype during larval development associated with diminished pit1 and gh1 expression during the embryonic stage. Additionally, in the juvenile stage, the development rate in prop1mut animals was restored, presenting similar standard lengths observed in WT animals.
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