Characterization of novel HLA-A*24:608N allele discovered in Koreans

A novel null HLA-A*24 allele, HLA-A*24:608N, was identified in five Korean subjects including three from a family and two separate individuals. This study was performed to discern its immunological function in transplantation settings. Because this null variant had deletions of approximately 12 k base pairs from intron 3 to 3' end of the HLA-A gene, low resolution HLA typing and amplicon-based next generation sequencing (NGS) typing methods had failed to assign it. Hybrid capture-based NGS method confirmed that this novel variant had a large deletion. T-lymphocyte crossmatching by complement-dependent lymphocytotoxicity and flow cytometry with a serum consisting anti-HLA-A24 antibody revealed negative results, implying that an individual with this allele would not carry a functioning A24 antigen. These findings highlight the importance of identifying a null HLA allele by employing appropriate molecular method and providing expected crossmatching outcomes in a real-world transplantation setting.

Comprehensive clinical characterization of patients with BRCA1: c.5017_5019del germline variant

Purpose

We provide evidence for the reclassification of the BRCA1:c.5017_5019del variant by presenting the clinicopathological characteristics, clinical outcomes, and family history of breast or ovarian cancer in 17 patients with this variant.

Methods

This study included breast or ovarian cancer patients tested for BRCA1/2 genes between January 2008 and June 2020 at 10 medical centers in Korea. We retrospectively reviewed 17 probands from 15 families who had the BRCA1:c.5017_5019del variant according to the electronic medical records.

Results

We present 10 breast cancer patients and 7 ovarian cancer patients from 15 families identified as having BRCA1:c.5017_5019del and a total of 19 cases of breast cancer and 14 cases of ovarian cancer in these families. The ratio of breast-to-ovarian cancer was 1.3:1. Breast cancer patients with this variant showed a rich family history of breast or ovarian cancer, 8 patients (80.0%). The mean age at diagnosis was 45.4 years and 6 patients (60.0%) were categorized into hormone-receptor-negative breast cancer. Also, the ovarian cancer patients with this variant showed strong family histories of breast and/or ovarian cancer in 4 patients (57.1%).

Conclusion

We presented clinical evidence for the reclassification of BRCA1:c.5017_5019del as a likely pathogenic variant (LPV). Reclassification as LPV could result in the prophylactic treatment and medical surveillance of probands, family testing recommendations, and appropriate genetic counseling of their families.

Genetic Counseling and Long-Term Surveillance Using a Multidisciplinary Approach in von Hippel-Lindau Disease

Background

von Hippel–Lindau (VHL) disease is an autosomal dominant disorder caused by variants of the VHL tumor suppressor gene (VHL). Early detection and treatment are essential to prevent morbidity and mortality. We evaluated the effectiveness of surveillance strategies and the utility of a VHL clinic with a multidisciplinary team for the first time in Korea.

Methods

The VHL clinic was organized at the Samsung Medical Center in 2011 and consisted of a multidisciplinary team, including an endocrinologist, urologist, general surgeon, neurosurgeon, ophthalmologist, otolaryngologist, and radiologist. Biochemical and imaging surveillance and personalized genetic counseling were conducted at the VHL clinic and patients were referred to the necessary departments upon detection of disease manifestation. We divided the patients in three groups (I–III) based on their compliance to VHL clinic attendance.

Results

Between 2011 and 2018, 50 VHL patients were identified by VHL molecular analysis and referred to the VHL clinic. Most patients regularly participated in imaging of the central nervous system (43/50, 86.0%) and of the abdomen (46/50, 92.0%). However, there were differences in compliance to determination of the catecholamine level, audiometry, and ophthalmic examination among the three groups.

Conclusions

We present the results of using a multidisciplinary team approach and showed that the VHL clinic strategy is useful for the comprehensive surveillance and management of VHL disease. We hope that VHL clinics will be widely set up in hospitals to improve prognosis in patients with VHL.

Case Report: Novel Splicing Variant in SH2D1A in a Patient With X-Linked Lymphoproliferative Syndrome Type 1

X-linked lymphoproliferative disease type 1 (XLP1), an X-linked recessive genetic disorder, is associated with primary immunodeficiency. Patients with XLP1 are susceptible to Epstein-Barr virus (EBV) infection. SH2D1A gene is known as the causative gene. We found a novel hemizygous variant of SH2D1A, c.162_201+31delinsTACAAGGACATATACA, from a 5-year-old male patient who had been diagnosed with EBV infection and Hodgkin's lymphoma. In targeted next-generation sequencing (NGS), complex variants at exon 2 were not consistently identified with two software programs. They showed a soft-clipped read pattern. The variant had a 71-bp deletion and a 16-bp insertion across exon 2 as confirmed by direct sequencing. As the variant was located within the exon-intron boundary, two aberrant transcripts were shown by RNA study. Although NGS method has a limitation in detecting large deletion/duplication variants, proper bioinformatics pipeline and careful review of data might enable the detection of complex variants.

Clinicopathological Characterization of Double Heterozygosity for BRCA1 and BRCA2 Variants in Korean Breast Cancer Patients

Purpose

Double heterozygosity (DH) for BRCA1 and BRCA2 variant is very rare with only a few cases reported, and most those in Caucasians. In this article, we present seven unrelated cases of DH for BRCA1/2 identified from a single institution in Korea, and describe the characteristics and phenotype of DH individuals compared to those with a single BRCA variant.

Materials and Methods

This study included 27,678 patients diagnosed with breast cancer and surgically treated at Samsung Medical Center (SMC) between January 2008 and June 2020. In total, 4,215 high-risk breast cancer patients were tested for the BRCA1/2 genes, and electronic medical records from 456 cases with pathogenic/likely pathogenic variants were reviewed.

Results

A younger mean age at diagnosis was associated with DH than a single variant of BRCA1/2. More triple-negative breast cancer and higher nuclear and histologic grade cancer occurred with DH than BRCA2 variant. All seven cases of DH were unrelated, and their mutation combinations were different. There were no Ashkenazi founder variants detected.

Conclusion

We suggest that patients with DH for BRCA1/2 variants develop breast cancer at a younger age, but the histopathologic features are similar to those of BRCA1.

Flow Cytometry for the Diagnosis of Primary Immunodeficiency Diseases: A Single Center Experience

Purpose

While there is an urgent need for diagnosis and therapeutic intervention in patients with primary immunodeficiency diseases (PIDs), current genetic tests have drawbacks. We retrospectively reviewed the usefulness of flow cytometry (FCM) as a quick tool for immunophenotyping and functional assays in patients suspected to have PIDs at a single tertiary care institute.

Methods

Between January 2001 and June 2018, patients suspected of having PIDs were subjected to FCM tests, including lymphocyte subset analysis, detection of surface- or intracellular-target proteins, and functional analysis of immune cells, at Samsung Medical Center, Seoul, Korea. The genetic diagnosis was performed using Sanger or diagnostic exome sequencing.

Results

Of 60 patients diagnosed with definite or probable PID according to the European Society of Immune Deficiencies criteria, 24 patients were provided with useful information about immunological dysfunction after initial FCM testing. In 10 patients, the PID diagnosis was based on abnormal findings in FCM testing without genetic tests. The FCM findings provided strong evidence for the diagnosis of severe combined immunodeficiency (n = 6), X-linked chronic granulomatous diseases (CGD) (n = 6), leukocyte adhesion deficiency type 1 (n = 3), X-linked agammaglobulinemia (n = 11), autoimmune lymphoproliferative syndrome-FASLG (n = 1), and familial hemophagocytic lymphohistiocytosis type 2 (n = 1), and probable evidence for autosomal recessive-CGD (n = 2), autosomal dominant-hyper-immunoglobulin E (IgE)-syndrome (n = 1), and STAT1 gain-of-function mutation (n = 1). In PIDs derived from PIK3CD (n = 2), LRBA (n = 2), and CTLA4 mutations (n = 3), the FCM test provided useful evidence of immune abnormalities and a tool for treatment monitoring.

Conclusions

The initial application of FCM, particularly with known protein targets on immune cells, would facilitate the timely diagnosis of PIDs and thus would support clinical decisions and improve the clinical outcome.

Clinical utility of FISH analysis in addition to G-banded karyotype in hematologic malignancies and proposal of a practical approach

Background

Fluorescence in situ hybridization (FISH) analysis can provide important information in the management of patients with hematologic malignancies. However, FISH performed in addition to G-banded karyotype can be labor-intensive and expensive. The aim of this study was to evaluate whether FISH gives additional information in the setting of adequate conventional cytogenetics in cases of hematologic malignancies.

Methods

Bone marrow aspirates were obtained from 135 patients at diagnosis (56 AML, 32 MDS, 20 ALL, and 27 MM) between 2005 and 2010. Interphase FISH was performed using the following probes: BCR/ABL1, AML1/ETO, PML/RARA, CBFB, MLL, EGR1, CEP8, and D7S486 for AML; CEP8, D20S108, EGR1, and D7S486 for MDS; BCR/ABL1, MLL, CDKN2A (p16), ETV6, and 6q21/c-myc for ALL; IgH, TP53, D13S25, IgH/CCND1, IgH/MAF, IgH/FGFR3, and 1q21/8p21 for MM. We compared the results of FISH with the corresponding aberrations identified by G-banded karyotype.

Results

Additional genetic aberrations detected by FISH (which were not identified by G-banded karyotype) were 4%, 9%, 50%, and 67% in AML, MDS, ALL, and MM, respectively. In ALL, CDKN2A and ETV6 FISH revealed additional genetic aberrations in 33% and 28% of cases, respectively. In MM, FISH was of benefit in detecting IgH, D13S25, TP53, and 1q21 rearrangements, not detected by G-banded karyotype (31%, 36%, 20%, and 40%, respectively).

Conclusion

These results suggest that performing FISH in addition to G-banded karyotype may contribute little additional genetic information in AML and MDS, whereas routine FISH analysis appears to be an efficient screening method in ALL and MM.

Percutaneous radiofrequency ablation of small hepatocellular carcinoma invisible on both ultrasonography and unenhanced CT: a preliminary study of combined treatment with transarterial chemoembolisation

The purpose of this study was to assess the feasibility and efficacy of percutaneous radiofrequency ablation combined with transarterial chemoembolisation (TACE) for the treatment of hepatocellular carcinoma that are invisible on both ultrasound and unenhanced CT. 73 patients with a total of 101 nodular hepatocellular carcinomas were referred for possible radiofrequency (RF) ablation. Of these, 14 lesions (14%) in 14 patients were invisible on both ultrasound and unenhanced CT. The invisible nodules averaged 1.2 cm in diameter (range, 0.8-2.0 cm; median, 1.1 cm). After segmental TACE, percutaneous RF ablation was performed if the index tumour was visible on fluoroscopy, ultrasound or CT. All cases of combined treatment were evaluated for size of ablative zone, complications, rate of technical effectiveness at 1-month follow-up CT and local tumour progression. After TACE, percutaneous RF ablation was technically feasible in 10 (71%) of the 14 nodules. RF ablation was performed with the guidance of fluoroscopy (n = 6, 42%), ultrasound (n = 2, 14%) or CT (n = 2, 14%). The mean diameter of the ablative zone by percutaneous RF ablation combined with TACE was 4.8+/-0.7 cm and 3.4+/-0.6 cm in the long and short axis, respectively. No major complications were documented. The primary technical effectiveness rate for nodules treated by combined treatment was 100% (10/10) at 1-month follow-up CT. No local tumour progression was found during the follow-up period (median 15 months; range 4-20 months). Percutaneous RF ablation combined with TACE is a feasible and effective technique for treating small hepatocellular carcinomas that are not visible on ultrasound or unenhanced CT.