A MinION-based Long-Read Sequencing Application With One-Step PCR for the Genetic Diagnosis of 21-Hydroxylase Deficiency

CONTEXT

Recently developed long-read sequencing (LRS) technology has been considered an option for CYP21A2 analysis. However, the clinical use of LRS for CYP21A2 analysis is limited.

OBJECTIVE

This study's objective is to develop an efficient and low-cost LRS system for CYP21A2 screening.

METHODS

A DNA fragment library was prepared in a single polymerase chain reaction (PCR) that covers the entire CYP21A2 gene and all known junctions caused by TNXB gene structural rearrangements, yielding a single 8-kb product of CYP21A2 or CYP21A1P/CYP21A2 chimera. After barcoding, the PCR products were sequenced on a MinION-based platform with Flongle Flow Cell R9.4.1 and R10.4.1.

RESULTS

The reference genotypes of 55 patients with 21-hydroxylase deficiency (21OHD) were established using the conventional method with multiplex ligation-dependent probe amplification (MLPA) and nested PCR. LRS using Flongle Flow Cell R9.4.1 yielded consistent results. Additionally, the recently updated LRS "duplex" analysis with Flongle flow cell R10.4.1 was tested to reveal an advantage of accurately sequencing a variant located on the homopolymer region. By introducing a barcode system, the cost was reduced to be comparable to that of conventional analysis. A novel single-nucleotide variation was discovered at the acceptor site of intron 7, c.940-1G > C. We also identified a subtype of the classical chimeric junction CH2, "CH2a," in the region from the latter part of intron 5 to exon 6.

CONCLUSION

We successfully established a novel low-cost and highly accurate LRS system for 21OHD genetic analysis. Our study provides insight into the feasibility of LRS for diagnosing 21OHD and other genetic diseases caused by structural rearrangements.

Phenotypic Variation in 46,XX Disorders of Sex Development due to the Fourth Zinc Finger Domain Variant of WT1: A Familial Case Report

INTRODUCTION

The variants in the zinc finger (ZF) domains 1-3 in WT1 are one of the major causes of 46,XY disorders of sex development (DSD). Recently, variants in the fourth ZF (ZF4 variants) were reported to cause 46,XX DSD. However, all the 9 patients reported were de novo, and no familial cases were identified.

CASE PRESENTATION AND RESULTS

The proband (16-year-old social female) had a 46,XX karyotype with dysplastic testes and moderate virilization in genitalia. A ZF4 variant, p.Arg495Gln, in WT1 was identified in the proband, her brother, and mother. The mother did not show any virilization with normal fertility, and the 46,XY brother developed normal puberty.

CONCLUSION

The phenotypic variations due to the ZF4 variant are extremely broad in 46,XX cases.

Clinical report: Chronic liver dysfunction in an individual with an AMOTL1 variant

AMOTL1 is a member of the Motin protein family and localizes to tight junctions and is involved in cell polarity and paracellular permeability. Pathological variants have been reported in three patients from two separate families in recent years. The clinical spectrum includes cleft lip and palate along with a high incidence of congenital cardiac disease and ear malformations. We report a case of AMOTL1 pathogenic variant in a 11-year-old male patient with nonspecific and chronic liver dysfunction accompanied by persistently elevated liver enzymes since early infancy. Liver biopsy at 8 years of age revealed a mildly dilated central vein and sinusoid with no specific etiology. Liver dysfunction is not a known clinical feature of AMOTL1 malfunction. However, given that the protein is known to be involved in angiogenesis, it may be inferred that abnormalities in this process may lead to liver dysfunction. This is the first report of liver dysfunction identified in a patient with AMOTL1 malfunction, which will shed light on other putative functions of the protein.

An eight-year-old girl with autoimmune polyglandular syndrome type3A that developed during the course of primary Epstein-Barr virus (EBV) infection: clinical implication of EBV in autoimmune thyroid disease

An eight-year-old girl was admitted for prolonged fever and general fatigue. Bilateral reddened and swollen tonsils covered with white fur and increased numbers of atypical lymphocytes in blood led to a diagnosis of infectious mononucleosis (IM) due to primary Epstein-Barr virus (EBV) infection, which was confirmed by a positive anti-EBV viral capsid antigen IgM antibody reaction. She had a swollen thyroid gland and glycosuria at admission, which persisted after IM resolved. Undetectable thyroid-stimulating hormone (TSH), increased thyroid hormone and elevated HbA1c levels led to a diagnosis of autoimmune polyglandular syndrome type3A, based on the presence of antibodies for TSH receptor and glutamic acid decarboxylase. The clinical significance of EBV infection in the development of autoimmune endocrine disorders has been discussed.

Hematopoietic stem cell transplantation recovers insulin deficiency in type 1 diabetes mellitus associated with IPEX syndrome

Immune dysregulation, polyendocrinopathy, enteropathy, and X-linked (IPEX) syndrome is an autoimmune disorder caused by the dysfunction of FOXP3, which leads to regulatory T-(Treg) cell dysfunction and subsequently autoimmunity including type 1 diabetes mellitus (T1D). Presently, allogeneic hematopoietic stem cell transplantation (HSCT) is a potential curative therapy for IPEX syndrome, but not for T1D. Generally, after complete loss of pancreatic β-cells, HSCT cannot improve the prognosis of T1D. Here, we report the case of a 16-year-old adolescent with late-onset of FOXP3 R347H mutation associated IPEX syndrome with T1D, where insulin dependency was ameliorated following HSCT. This patient with insulin-dependent diabetes mellitus required insulin dosage of 1.28 U/kg/day for 1 month before HSCT. Although the results of glucose homeostasis before HSCT revealed impaired insulin secretion and low ΔC-peptide immunoreactivity (CPR, 1.0 ng/mL), the patient withdrew insulin infusion and remained euglycemic at 15 months after HSCT, and had normal β-cell function with improved ΔCPR (3.4 ng/mL) at 20 months after HSCT. The present case suggests that HSCT for T1D-associated IPEX syndrome improves Treg deficiency and prevents elimination of β-cells. We speculate that the period from the onset of T1D to HSCT could affect the therapeutic efficacy for T1D with IPEX, and early intervention with HSCT before or immediately after the onset of DM can rescue β-cells and remit T1D completely. Our study elaborates not only the therapeutic strategy for T1D with IPEX, but also the pathogenic mechanism in general T1D.

Expression of osteoclast differentiation factor and osteoclastogenesis inhibitory factor in rat osteoporosis induced by immunosuppressant FK506

Immunosuppressant drugs are currently required by transplant recipients for the remainder of their lives, despite the many adverse effects associated with these therapies. Acute osteoporosis is one such effect, and a reproducible osteoporosis model has been established through the administration of the immunosuppressant drug FK506 in rats. The cause of this osteoporosis has been shown to be abnormal osteoclast proliferation, altering the process of bone remodeling. However, the reasons why FK506 induces osteoclast proliferation and whether this process is mediated by cytokine changes or an increase in bone resorption factors have been unclear. An investigation was therefore conducted focusing on the recent discoveries of osteoclast differentiation factor (ODF) and osteoclastogenesis inhibitory factor (OCIF). These factors led to elucidation of the osteoclast differentiation-maturation mechanism. An osteoporosis model was produced in rats utilizing intramuscular FK506 injection (1 mg/kg) for 28 consecutive days. Trabecular bone resorption was observed inferior to enchondral ossification in the FK506 group, and tartrate resistant acid phosphatase (TRAP) staining revealed a clear increase in osteoclasts at the site of enchondral ossification, relative to the control group. Real-time PCR and in situ hybridization (ISH) demonstrated minimal differences in OCIF expression between control and the treatment groups. However, Real-time PCR revealed clearly increased ODF expression in the treatment group. ODF expression was also shown to be increased in the treatment group using ISH. This was histologically consistent with a region of osteoclast proliferation inferior to enchondral ossification. The results of this study support the hypothesis that FK506-mediated osteoporosis occurs by action of the drug on osteoclasts, promoting expression of ODF messenger ribonucleic acid (mRNA) and thus prompting osteoclast differentiation and maturation.