Identification of the novel allele, HLA-A*30:01:22, in a Saudi individual.

A single nucleotide substitution in exon 5 of HLA-A*30:01:01:01 results in the novel HLA-A*30:01:22 allele.

Graft-versus-host disease after pediatric liver transplantation: A diagnostic challenge.

BACKGROUND: Graft-versus-host disease (GVHD) is a rare but serious complication after pediatric liver transplantation (LTx). Early diagnosis is difficult due to nonspecific presenting symptoms and non-pathognomonic skin histopathological features. The aim of this article was to describe a case of pediatric GVHD after LTx and to review available data on pediatric GVHD highlighting the diagnostic difficulty. We also propose a diagnostic algorithm to improve the diagnostic capability and increase clinical awareness about this potentially fatal condition. METHODS: We did a comprehensive literatures review on studies on GvHD following pediatric LTx between 1990 and February 2021, chimerism study by short tandem repeat (STR), HLA typing by sequence-specific oligonucleotide (SSO) method, and flowcytometry crossmatch. RESULTS: Our search yielded 23 case reports. The most common clinical manifestations were fever and rash (91%) followed by diarrhea. Mortality rate was 36.8% mainly due to sepsis and organ failure. Diagnosis was challenging and chimerism study to confirm donor engraftment was performed on only half of the cases. Prevalence of "donor dominant HLA one-way matching" typically occurs in homozygous parents-to-child transplantation was 75% in cases with HLA testing. CONCLUSION: So far, there are no available standard diagnostic criteria for GVHD following pediatric LTx. Recognition of multiple risk factors through proper laboratory assessment can predict the occurrence, and early chimerism study can confirm suggestive clinical manifestation. The strong likelihood of developing GVHD in "donor one-way HLA match" and the severe problems imposed by this complication may justify avoidance of HLA homozygous parent's donation.

Discrepant Antibody Testing Results: Which One to Believe?

The impact of solid-phase immunoassay for HLA antibody detection on the field of transplantation has been extremely significant by providing the most sensitive and precise method for characterization of HLA antibodies. However, despite all the benefits, technical limitations and inherent artifacts represent significant challenges, particularly with Luminex-based single-antigen bead (SAB) assay. Discordant results between antibody detection (screening assay) and identification (SAB) is not uncommon. Positive SAB assay in the context of negative screening testing is well documented and attributed to altered tertiary structure of HLA molecules exposing new epitopes or detection of naturally occurring antibodies. However, there are few reports that addressed the opposite scenario when negative SAB appeared in the context of positive screening assay. In such discrepant results, unmissed HLA antibody has to be excluded with certainty by other tests; however, with the availability of variable assays it may be difficult to choose the best combinations that clarify discrepancy without adding more confusion. Here we describe the results of correlation between 2 antibody screening solid-phase immunoassays (LABScreen Mixed using Luminex and FlowPRA Screen) on conventional flow cytometry and compare their outcomes with SAB and crossmatch results.