Unexpected Genotype in a Non-Transfusion Dependent Thalassemia Family.

Non-transfusion dependent thalassemia (NTDT) is an inherited hemoglobin disorder characterized by an α/non-α globin chain imbalance of variable severity, resulting in a wide spectrum of clinical manifestations. The coinheritance of additional α genes with a beta-thalassemia heterozygous mutation has a well-known negative effect. Triplication or quadruplication alone are mostly found by chance, but the coinheritance with ß mutations can worsen the very mild anemia to a more severe hematological and clinical phenotype causing NTDT, depending on the severity of beta mutations. We describe a case of a 38-year-old ß-thalassemia trait, pregnant woman at 33 weeks of gestation with supernumerary α-globin genes and two ß-globin defects.

Hb Milano [α109(G16)Leu→Pro (CTG>CCG); HBA1: c.329T>C]: A Novel Variant on the α1-Globin Gene in an Italian Family.

Interest in α-globin point mutations has increased in the past few years because nondeletional variations can affect protein function and stability, giving rise to hemoglobin (Hb) variants that present a wide spectrum of phenotypes, from asymptomatic forms to hemolytic anemia. We describe a novel α1-globin gene variant, which we have named Hb Milano [α109(G16)Leu→Pro (CTG>CCG); HBA1: c.329T>C]. We performed high performance liquid chromatography (HPLC) to carry out Hb analysis, capillary electrophoresis (CE) for Hb separation and quantitation of Hb subtypes, two tests on stroma-free lysates for evaluating Hb stability, multiplex ligation-dependent probe amplification (MLPA) to detect deletions/duplications within the α gene cluster and Sanger sequencing of the α-globin genes. No abnormal Hb variants were identified by HPLC and CE. Isopropanol and stability tests were negative. The peripheral blood film showed no inclusions such as Hb H or Heinz bodies. Multiplication ligation-dependent probe amplification of the α-globin gene cluster detected a heterozygosity for the -α3.7 (rightward) deletion. Direct sequencing of the α-globin genes identified the Hb Milano variant on the HBA1 gene. No mutations were found on the HBA2 gene. The clinical consequences of the Hb Milano variant differ based on the genotype: according to our study, the hematological parameters range from a marked microcythemia with mild anemia if the variant is coinherited with an α gene deletion, to mild microcytosis when the variant is not associated with α gene deletions.

Gap Junctions Are Involved in the Rescue of CFTR-Dependent Chloride Efflux by Amniotic Mesenchymal Stem Cells in Coculture with Cystic Fibrosis CFBE41o- Cells.

We previously found that human amniotic mesenchymal stem cells (hAMSCs) in coculture with CF immortalised airway epithelial cells (CFBE41o- line, CFBE) on Transwell® filters acquired an epithelial phenotype and led to the expression of a mature and functional CFTR protein. In order to explore the role of gap junction- (GJ-) mediated intercellular communication (GJIC) in this rescue, cocultures (hAMSC : CFBE, 1 : 5 ratio) were studied for the formation of GJIC, before and after silencing connexin 43 (Cx43), a major component of GJs. Functional GJs in cocultures were inhibited when the expression of the Cx43 protein was downregulated. Transfection of cocultures with siRNA against Cx43 resulted in the absence of specific CFTR signal on the apical membrane and reduction in the mature form of CFTR (band C), and in parallel, the CFTR-dependent chloride channel activity was significantly decreased. Cx43 downregulation determined also a decrease in transepithelial resistance and an increase in paracellular permeability as compared with control cocultures, implying that GJIC may regulate CFTR expression and function that in turn modulate airway epithelium tightness. These results indicate that GJIC is involved in the correction of CFTR chloride channel activity upon the acquisition of an epithelial phenotype by hAMSCs in coculture with CF cells.

A New Targeted CFTR Mutation Panel Based on Next-Generation Sequencing Technology.

Searching for mutations in the cystic fibrosis transmembrane conductance regulator gene (CFTR) is a key step in the diagnosis of and neonatal and carrier screening for cystic fibrosis (CF), and it has implications for prognosis and personalized therapy. The large number of mutations and genetic and phenotypic variability make this search a complex task. Herein, we developed, validated, and tested a laboratory assay for an extended search for mutations in CFTR using a next-generation sequencing-based method, with a panel of 188 CFTR mutations customized for the Italian population. Overall, 1426 dried blood spots from neonatal screening, 402 genomic DNA samples from various origins, and 1138 genomic DNA samples from patients with CF were analyzed. The assay showed excellent analytical and diagnostic operative characteristics. We identified and experimentally validated 159 (of 188) CFTR mutations. The assay achieved detection rates of 95.0% and 95.6% in two large-scale case series of CF patients from central and northern Italy, respectively. These detection rates are among the highest reported so far with a genetic test for CF based on a mutation panel. This assay appears to be well suited for diagnostics, neonatal and carrier screening, and assisted reproduction, and it represents a considerable advantage in CF genetic counseling.

Hb Mozhaisk [ß92(F8)His→Arg; HBB: c.278A>G] as a De Novo Mutation in a Child of Mixed Ethnic Origins.

Approximately 150 variants described in the HbVar database have been found to be unstable and about 80.0% of these are on the ß-globin gene. We describe the case of a 3-year-old child who presented at the emergency room with fever and asthenia. Hematological data suggested severe hemolytic anemia. Sequencing of the ß-globin gene revealed the mutation HBB: c.278A>G at codon 92 in a heterozygous state, reported as Hb Mozhaisk in the HbVar database. Other family members did not have Hb Mozhaisk, thus, this variant is due to a de novo mutation. Because of the rarity of this globin variant, we believe it is important to report similar cases, to have a more complete phenotype description of the pathology and define an adequate reproductive risk for couples, considering the dominant inheritance pattern (hence an inheritance risk of 50.0%).