Erythrocyte phenotype in a pregnant woman of Sri Lanka. Description of the case and complications related to communication problems

Background. TheBombay phenotype is a rare genetic trait which is characterized by the absence of A, B and H antigens on red cells as well as in body secretions. The serum shows the presence of antibodies against antigen H. Patients with this rare blood type are not easily transfusable. We had observed a woman aged 18, at the 20th week of pregnancy, native ofSri Lanka, with an IgG and IgM class anti-H. We report the case and the clinical issues arisen. Materials and methods. The determination of ABO, Rh[D] group, the indirect antiglobulin test (IAT) were performed in tube techniques and in neutral gel microcolumn. Detection for antibodies was performed using ID-Card LISS-Coombs microtubes, in solid phase and with tube techniques. For molecular analysis, the FUT1 and FUT2 genes were sequenced using BigDye terminator v1.1. The study of FUT2 gene was performed after extraction of mRNA using Qiagen kit RNase and then reverse-transcribed into cDNA. Results. TheBombay phenotype was confirmed by serological and molecular analysis techniques. The patient, in collaboration with a cultural mediator, was informed of her immunohaematological condition and a program of assistance was proposed to her. Unfortunately the patient did not return for the next visit, despite of a telephone reminder. During childbirth a haemorrhage occurred and a request of compatible blood for an urgent transfusion arrived at our transfusion service. Fortunately, the haemorrhage was arrested and the patient didn’t need to have any transfusions. Discussion. This case emphasizes the need for an efficient management of rare blood types that are more and more frequent as a result of migration. It is necessary to organize, in strategic points of the national territory, reference centres with better diagnostic capabilities and implement freezing of red blood cells with rare phenotype for diagnostic and therapeutical use. Communication issues are as well important in dealing with this emerging phenomenon

Antigenic sin and multiple breakthrough infections drive converging evolution of COVID-19 neutralizing responses

Understanding the evolution of the B cell response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants is fundamental to design the next generation of vaccines and therapeutics. We longitudinally analyze at the single-cell level almost 900 neutralizing human monoclonal antibodies (nAbs) isolated from vaccinated people and from individuals with hybrid and super hybrid immunity (SH), developed after three mRNA vaccine doses and two breakthrough infections. The most potent neutralization and Fc functions against highly mutated variants belong to the SH cohort. Repertoire analysis shows that the original Wuhan antigenic sin drives the convergent expansion of the same B cell germlines in vaccinated and SH cohorts. Only Omicron breakthrough infections expand previously unseen germ lines and generate broadly nAbs by restoring IGHV3-53/3-66 germ lines. Our analyses find that B cells initially expanded by the original antigenic sin continue to play a fundamental role in the evolution of the immune response toward an evolving virus

HLA class I expression on human platelets is highly variable and correlates with distinct allele group frequencies

Background: Human leukocyte antigen (HLA) class I molecules are expressed on platelets and can represent a source of alloimmunization in recipients of platelet transfusions. HLA mismatch between donors and recipients may be associated with the induction of anti-HLA antibodies, which can culminate in refractoriness to platelet transfusions. In the present study we analyzed HLA allele group frequencies and HLA expression levels on human platelets from blood donors. Materials and methods: Platelet-rich plasma was collected from 139 donors to monitor platelet HLA class I expression by flow cytometry. DNA from donors with high and low platelet HLA expression was used in the genotype studies. Frequencies of large and normal-sized platelet subpopulations were determined and HLA class I expression was studied. Mean platelet volume (MPV) and platelet large-cell ratio (P-LCR) were analyzed in both groups of donors. Results: The analysis showed variable platelet HLA class I expression with significant differences among donors. HLA class I allele group frequencies in donors with high and low platelet HLA expression showed distinctive genotypic features strictly related to expression level. The main allele groups found in samples with high platelet HLA class I expression were HLA-A*02, -A*68, -B*15, -B*49, and -C*03. Platelet HLA class I expression did not change over time or during freezing-thawing cycles. The analysis of platelet subpopulations showed a statistically significant higher expression of HLA class I molecules on large platelets than on normal-sized platelets. Moreover, donors with high HLA class I expression showed a higher frequency of large platelets (p<0.0001). The analysis of P-LCR in both groups of donors showed a statistically significant difference (p<0.05) within high HLA-expressing donors. Discussion: Our data suggest an allele-dependent expression of HLA class I molecules on human platelets with distinct HLA allele group frequencies and different platelet subpopulation frequencies among blood donors

A new asymptomatic case of methylmalonic acidemia (MMA) identified by MS/MS newborn screening

A newborn screening pilot study using tandem mass spectrometry has been set up since 2003. To date more than 15000 newborns have been screened. We reported a newborn affected by benign MMA identified by MS/MS. The analysis of derivatized acylcarnitines and amino acids in dried blood spot was performed using PerkinElmer NeoGram MS2 Kit. The analysis of patient’s blood sample obtained at 3 days of life showed an elevation of propionylcarnitine (C3: 4.38 μM) slightly below the cut-off value (4.6 μM) and a C3/C2 ratio higher than cutoff ( C3/C2 0.20, cutoff 0.18), therefore a repeat of blood spot collection was requested. This second sample, obtained at the age of 28 days, showed a marked increase of C3 and C3/C2. The organic acid analysis in urine demonstrated an increase of methylmalonic acid. The (hydroxy)cobalamin administration (loading) test was carried out and no significant reduction of methylmalonic acid excretion in urine was found. Therefore a deficiency of methylmalonyl-CoA mutase (EC 5.4.99.2) enzyme was suspected. Molecular genetic analysis was performed on the 13 exons and intron- exon boundaries of methylmalonyl-CoA mutase gene (c.DNA NM_00025; g.DNA NT_007592) were analyzed by direct sequencing. The patient resulted compound heterozygote for two already described mutations: N219Y (c.655A>T) and R694W (c.2080C>T). The mutations were confirmed in the parents. The N219Y is a quite frequent mutation in MMA (19% alleles in Caucasians). It was already described associated to severe phenotype (mut0) with low or absent residual enzymatic activity. The Asn 219 is a conserved amino acid and is located at the fourth β strand of the substrate binding (α/β)8 barrel. Modelling analysis suggests that this mutation gives impaired folding and/or poor stability of the protein. The R264W mutation was associated to a milder phenotype (mut-). This residue is located in the protein pocket binding dimethylbenzimidazole portion of cobalamin molecule. Being the protein an homodimer, we suppose that the compound heterozigosity mut0/mut- gives enough molecules with residual enzymatic activity to manifest a milder phenotype. Conclusions: 1- Benign MMAs can be identified using MS/MS in newborn screening. MMA disorders may not produce significant concentrations of C3 and will not be detected. The evaluation of C3/C2 ratio is important to reduce the number of false positive and false negative results. 2- Molecular analysis could be an important tool to predict clinical phenotype 3-The early detection and therapy have had a favorable effect on prevention of metabolic decompensation. However, a long-term study is necessary to assess whether the early detection and intervention may improve the outcome

The natural history of 6-pyruvoyl-tetrahydropterin synthase (PTPS). A late diagnosed case.

viene riportato un paziente con sindrome di Parkinson e depressione affetto da deficit di PTPS e diagnosticato all'età di 32 anni

Tyrosine hydroxylase deficiency presenting with a Biphasic Clinical Course

Tyrosine hydroxylase deficiency, a cause of the autosomal recessive form of L-DOPA responsive dystonia, has been associated with a broad spectrum of movement disorders and clinical courses. We describe a new patient presenting with an early onset spastic paraplegia who later developed a progressive generalized dystonic-dyskinetic syndrome. He markedly improved with a very low dosage of L-DOPA/carbidopa, while higher dosages were not tolerated. Two novel mutations (p.G414R/p.L510Q) were detected in the TH gene