Michał Matysiak

Ribosomal Protein L5 and L11 Mutations Are Associated with Cleft Palate and Abnormal Thumbs in Diamond-Blackfan Anemia Patients

Diamond-Blackfan anemia (DBA), a congenital bone-marrow-failure syndrome, is characterized by red blood cell aplasia, macrocytic anemia, clinical heterogeneity, and increased risk of malignancy. Although anemia is the most prominent feature of DBA, the disease is also characterized by growth retardation and congenital anomalies that are present in approximately 30%-50% of patients. The disease has been associated with mutations in four ribosomal protein (RP) genes, RPS19, RPS24, RPS17, and RPL35A, in about 30% of patients. However, the genetic basis of the remaining 70% of cases is still unknown. Here, we report the second known mutation in RPS17 and probable pathogenic mutations in three more RP genes, RPL5, RPL11, and RPS7. In addition, we identified rare variants of unknown significance in three other genes, RPL36, RPS15, and RPS27A. Remarkably, careful review of the clinical data showed that mutations in RPL5 are associated with multiple physical abnormalities, including craniofacial, thumb, and heart anomalies, whereas isolated thumb malformations are predominantly present in patients carrying mutations in RPL11. We also demonstrate that mutations of RPL5, RPL11, or RPS7 in DBA cells is associated with diverse defects in the maturation of ribosomal RNAs in the large or the small ribosomal subunit production pathway, expanding the repertoire of ribosomal RNA processing defects associated with DBA.

Ribosomal Protein Genes RPS10 and RPS26 Are Commonly Mutated in Diamond-Blackfan Anemia

Diamond-Blackfan anemia (DBA), an inherited bone marrow failure syndrome characterized by anemia that usually presents before the first birthday or in early childhood, is associated with birth defects and an increased risk of cancer. Although anemia is the most prominent feature of DBA, the disease is also characterized by growth retardation and congenital malformations, in particular craniofacial, upper limb, heart, and urinary system defects that are present in approximately 30%-50% of patients. DBA has been associated with mutations in seven ribosomal protein (RP) genes, RPS19, RPS24, RPS17, RPL35A, RPL5, RPL11, and RPS7, in about 43% of patients. To continue our large-scale screen of RP genes in a DBA population, we sequenced 35 ribosomal protein genes, RPL15, RPL24, RPL29, RPL32, RPL34, RPL9, RPL37, RPS14, RPS23, RPL10A, RPS10, RPS12, RPS18, RPL30, RPS20, RPL12, RPL7A, RPS6, RPL27A, RPLP2, RPS25, RPS3, RPL41, RPL6, RPLP0, RPS26, RPL21, RPL36AL, RPS29, RPL4, RPLP1, RPL13, RPS15A, RPS2, and RPL38, in our DBA patient cohort of 117 probands. We identified three distinct mutations of RPS10 in five probands and nine distinct mutations of RPS26 in 12 probands. Pre-rRNA analysis in lymphoblastoid cells from patients bearing mutations in RPS10 and RPS26 showed elevated levels of 18S-E pre-rRNA. This accumulation is consistent with the phenotype observed in HeLa cells after knockdown of RPS10 or RPS26 expression with siRNAs, which indicates that mutations in the RPS10 and RPS26 genes in DBA patients affect the function of the proteins in rRNA processing.

Frameshift mutation in p53 regulator RPL26 is associated with multiple physical abnormalities and a specific pre-ribosomal RNA processing defect in diamond–blackfan anemia†

Diamond–Blackfan anemia (DBA) is an inherited form of pure red cell aplasia that usually presents in infancy or early childhood and is associated with congenital malformations in ∼30–50% of patients. DBA has been associated with mutations in nine ribosomal protein (RP) genes in about 53% of patients. We completed a large‐scale screen of 79 RP genes by sequencing 16 RP genes (RPL3, RPL7, RPL8, RPL10, RPL14, RPL17, RPL19, RPL23A, RPL26, RPL27, RPL35, RPL36A, RPL39, RPS4X, RPS4Y1, and RPS21) in 96 DBA probands. We identified a de novo two‐nucleotide deletion in RPL26 in one proband associated with multiple severe physical abnormalities. This mutation gives rise to a remarkable ribosome biogenesis defect that affects maturation of both the small and the large subunits. We also found a deletion in RPL19 and missense mutations in RPL3 and RPL23A, which may be variants of unknown significance. Together with RPL5, RPL11, and RPS7, RPL26 is the fourth RP regulating p53 activity that is linked to DBA. Hum Mutat 33:1037–1044, 2012.

Pearson marrow pancreas syndrome in patients suspected to have Diamond-Blackfan anemia

Pearson marrow pancreas syndrome (PS) is a multisystem disorder caused by mitochondrial DNA (mtDNA) deletions. Diamond-Blackfan anemia (DBA) is a congenital hypoproliferative anemia in which mutations in ribosomal protein genes and GATA1 have been implicated. Both syndromes share several features including early onset of severe anemia, variable nonhematologic manifestations, sporadic genetic occurrence, and occasional spontaneous hematologic improvement. Because of the overlapping features and relative rarity of PS, we hypothesized that some patients in whom the leading clinical diagnosis is DBA actually have PS. Here, we evaluated patient DNA samples submitted for DBA genetic studies and found that 8 (4.6%) of 173 genetically uncharacterized patients contained large mtDNA deletions. Only 2 (25%) of the patients had been diagnosed with PS on clinical grounds subsequent to sample submission. We conclude that PS can be overlooked, and that mtDNA deletion testing should be performed in the diagnostic evaluation of patients with congenital anemia.

Identification and characterization of acute infection with parvovirus B19 genotype 2 in immunocompromised patients in Poland.

Parvovirus B19 (B19V) is divided into three genotypes. Genotypes 2 and 3 may cause diagnostic difficulties and their epidemiology is not well understood. In the present study the prevalence of B19V genotypes in patients with symptomatic infection in Poland was evaluated and the course of infection in patients infected with non‐genotype 1 strains is described. Real‐time PCR, able to detect all three genotypes of B19V was used to screen patient plasma samples. Sixty‐nine, mainly acute‐phase B19V DNA positive cases were identified in patients from hematological and obstetric/gynecological wards between 2004 and 2008. Thirty patients were studied in greater detail and genotyping was performed by analysis of the NS1/VP1u region. The majority of samples were genotype 1. However two (6.6%) strains were identified as genotype 2, associated with high viremia and identified in a kidney transplant recipient with anemia and a leukemia patient, following chemotherapy, with pancytopenia. A change of immunosuppression treatment in the former and treatment with intravenous immunoglobulin in latter, resulted in normalization of clinical parameters, and whilst viral loads fell, B19V DNA was still detectable. The kidney transplant recipient subsequently became pregnant with no clinical complications, although persistently infected with B19V genotype 2. This is the first description of symptomatic cases of genotype 2 B19V infection in Eastern Europe suggesting that acute infection, particularly among immunocompromised patients with these virus strains may be more prevalent than thought. J. Med. Virol. 83:142–149, 2011.

Additional genetic risk factor for death in children with acute lymphoblastic leukemia: A common polymorphism of the MTHFR gene

The presence of metabolically important genetic polymorphisms may affect treatment efficacy in patients with malignancies. The objective of this prospective multicenter study was to evaluate the role of selected polymorphisms of genes associated with metabolism of chemotherapeutic drugs as prognostic markers in children with acute lymphoblastic leukemia.

Biallelic loss of CDKN2A is associated with poor response to treatment in pediatric acute lymphoblastic leukemia

Abstract The inactivation of tumor suppressor genes located within 9p21 locus (CDKN2A, CDKN2B) occurs in up to 30% of children with B-cell precursor acute lymphoblastic leukemia (BCP-ALL), but its independent prognostic significance remains controversial. In order to investigate the prognostic impact of deletions and promoter methylation within 9p21, 641 children with newly diagnosed BCP-ALL using methylation specific multiplex ligation-dependent probe amplification (MS-MLPA) were investigated. A total of 169 (26.4%) microdeletions in 9p21 were detected, of which 71 were homozygous. Patients with CDKN2A homozygous deletions were older at diagnosis (p < .001), more frequently steroid resistant (p = .049), had higher WBC count (p < .001), higher MRD at Day 15 (p = .013) and lower relapse-free survival [p = .028, hazard ratio: 2.28 (95% confidence interval: 1.09–4.76)] than patients without these alterations. CDKN2A homozygous deletions coexisted with IKZF1 and PAX5 deletions (p < .001). In conclusion, CDKN2A homozygous deletions, but not promoter methylation, are associated with poor response to treatment and increased relapse risk of pediatric BCP-ALL.

Promoter methylation and expression levels of selected hematopoietic genes in pediatric B-cell acute lymphoblastic leukemia.

Background Precursor B-cell acute lymphoblastic leukemia (B-cell ALL) is the most common neoplasm in children and is characterized by genetic and epigenetic aberrations in hematopoietic transcription factor (TF) genes. This study evaluated promoter DNA methylation and aberrant expression levels of early- and late-acting hematopoietic TF genes homeobox A4 and A5 (HOXA4 and HOXA5), Meis homeobox 1 (MEIS1), T-cell acute lymphocytic leukemia 1 (TAL1), and interferon regulatory factors 4 and 8 (IRF4 and IRF8) in pediatric B-cell ALL. Methods Blood samples of 38 ALL patients and 20 controls were obtained. DNA was treated with sodium bisulfite and DNA methylation level of HOXA4, HOXA5, MEIS1, TAL1, IRF4, and IRF8 was assessed using quantitative methylation-specific polymerase chain reaction (PCR). Relative gene expression was measured using quantitative reverse transcription-PCR. Results Aberrant methylation of TAL1, IRF8, MEIS1, and IRF4 was observed in 26.3%, 7.9%, 5.3%, and 2.6% patients, respectively, but not in controls. HOXA4 and HOXA5 were methylated in some controls and hypermethylated in 16% and 5% patients, respectively. IRF8, MEIS1, and TAL1 expression was lower in patients than in controls. MEIS1 expression was inversely correlated with white blood cell (WBC) count. HOXA4 expression was down-regulated in patients with high risk according to the National Cancer Institute (NCI) classification. TAL1 methylation was slightly elevated in patients aged >9 years and in patients showing relapse, suggesting its potential prognostic value. Conclusion Aberrant methylation and expression of the selected hematopoietic genes were correlated with demographic/clinical prognostic factors of pediatric ALL, such as age, WBC count, and NCI risk classification.

Polymorphism of the thymidylate synthase gene and risk of relapse in childhood ALL

Polymorphisms of genes encoding proteins involved in drug metabolism can influence the efficacy of leukemia treatment. In this population-wide study we aimed to evaluate selected, metabolically active genetic polymorphisms as prognostic markers of treatment efficacy in acute lymphoblastic leukemia (ALL). A total of 51 cases of leukemia relapse were diagnosed in a group of 354 patients with ALL. A strong association between promoter tandem repeat polymorphism of the thymidylate synthase gene and the relapse frequency was found. We believe that genotyping for this variant should be performed in patients treated for ALL to enable further optimizing of treatment protocols.

Giant cell hepatitis with autoimmune hemolytic anemia in children: proposal for therapeutic approach.

Background and Objective: Giant cell hepatitis (GCH) with autoimmune hemolytic anemia (AIHA) is a rare, progressive disorder in infants and young children. The disease is aggressive and may lead to liver or multiorgan failure with fatal prognosis. Therapy with anti-CD20 monoclonal antibody, rituximab (Rtx), proved effective. The primary objective of the study was to evaluate therapy for severe GCH with AIHA. Methods: We report on 5 cases of severe GCH with AIHA treated in our department between 2006 and 2011. Results: The median age of the children was 7 months (2–12 months), follow-up lasted 44 months (12–78 months), median (min-max), and the main observed symptoms were jaundice and hepatosplenomegaly. All of the children had positive direct Coombs test and biopsy-proven giant cell transformation of hepatocytes. Liver failure was observed in 3 children. First-line therapy (prednisone, azathioprine) proved ineffective in all but 1 of the patients, who initially responded to the treatment but relapsed after 4 months. The child subsequently developed hemophagocytic lymphohistiocytosis and died 2 months after hemopoietic stem cell transplantation. Four remaining patients finally achieved complete remission after 4 to 6 doses of Rtx. Conclusions: We propose Rtx as the treatment of choice for severe GCH with AIHA in the early stages of the disease, provided steroids and azathioprine are ineffective.