Molecular diagnostics of the HBB gene in an Omani cohort using bench-top DNA Ion Torrent PGM technology.

Hemoglobinopathies, such as sickle cell disease (SCD) and beta-thalassemia major (TM), are severe diseases and the most common autosomal recessive condition worldwide and in particular in Oman. Early screening and diagnosis of carriers are the key for primary prevention. Once a country-wide population screening program is mandated by law, a sequencing technology that can rapidly confirm or identify disease-causing mutations for a large number of patients in a short period of time will be necessary. While Sanger sequencing is the standard protocol for molecular diagnosis, next generation sequencing starts to become available to reference laboratories. Using the Ion Torrent PGM sequencer, we have analyzed a cohort of 297 unrelated Omani cases and reliably identified mutations in the beta-globin (HBB) gene. Our model study has shown that Ion Torrent PGM can rapidly sequence such a small gene in a large number of samples using a barcoded uni-directional or bi-directional sequence methodology, reducing cost, workload and providing accurate diagnosis. Based on our results we believe that the Ion Torrent PGM sequencing platform, able to analyze hundreds of patients simultaneously for a single disease gene can be a valid molecular screening alternative to ABI sequencing in the diagnosis of hemoglobinopathies and other genetic disorders in the near future.

Prevention strategies for severe hemoglobinopathies in endemic and nonendemic immigration countries: the Latium example.

OBJECTIVE: To review prevention data for hemoglobinopathies from Latium, a large Italian region with a considerable immigrant population and with a well-established regional prevention program. METHOD: All data pertaining to population screening for hemoglobinopathies in the Latium region were reviewed for the period 1994-2007. Screening was performed universally in secondary schools and to pregnant couples at the time of prenatal care. We have examined the trends in positive screening results as well as the type of hemoglobinopathies detected during the study period, and we have correlated them to the type of population (immigrant vs indigenous). RESULTS: From 1994 to 2007, 167 235 individuals were examined for carrier status for hemoglobinopathies, and 10 353 of them (6.2%) were immigrants. We have registered a threefold increase in rates of screen-positive subjects who belonged to ethnic minorities during the study period (from 2.7% in 1994 to 9.8% in 2007). Over half of the screen-positive subjects (5397/10 353) presented no hematological anomalies, 24% (n = 2472) had iron deficiency, and 24% (n = 2484) was classified as putative carriers. Among the last group, 22.6% were carriers of beta-thalassemia, 48% were suspected alpha-thalassemia carriers, and the remainder had less common hemoglobinopathies. While the prevention program resulted in nearly zero births of autochthonous newborns affected by severe hemoglobinopathies, a rise in number of affected individuals was noted among immigrants. Screening of secondary school students was accepted by 67% of immigrant parents, resulting in 9737 pupils screened between 2002 and 2006. CONCLUSION: Existing preventive programs for severe hemoglobinopathies should adapt to changes in population ethnicities. Screening for hemoglobinopathies at school age is an efficient strategy.

Segmental duplications involving the alpha-globin gene cluster are causing beta-thalassemia intermedia phenotypes in beta-thalassemia heterozygous patients.

We describe two cases of simple heterozygosity for the common beta degrees -thalassemia mutation beta 39 (C-->T), both presenting with a thalassemia intermedia phenotype. In both cases synergic effect deriving from membrane defects or red cell enzyme deficiencies were excluded. In one case a triplication of the alpha-globin genes was found which did not justify the severity of the transfusion-dependent phenotype. Multiplex ligation-dependent probe amplification (MLPA) analysis of the alpha-globin gene cluster revealed two new rearrangements, consisting of a full duplication of the alpha-globin genes locus including the upstream regulatory element. In one case the duplication was in the presence of the common anti-alpha(3.7) triplication in trans, resulting in a total of 7 active alpha-globin genes. In the other case the duplicated allele and the normal allele in trans resulted into a total of 6 active alpha-globin genes. We report the clinical and hematological data and the molecular analysis and discuss the occurrence of alpha-globin genes duplication defects in cases of beta-thalassemia heterozygotes with thalassemia intermedia phenotypes.

Variation of CNV distribution in five different ethnic populations.

Recent studies have revealed a new type of variation in the human genome encompassing relatively large genomic segments ( approximately 100 kb-2.5 Mb), commonly referred to as copy number variation (CNV). The full nature and extent of CNV and its frequency in different ethnic populations is still largely unknown. In this study we surveyed a set of 12 CNVs previously detected by array-CGH. More than 300 individuals from five different ethnic populations, including three distinct European, one Asian and one African population, were tested for the occurrence of CNV using multiplex ligation-dependent probe amplification (MLPA). Seven of these loci indeed showed CNV, i.e., showed copy numbers that deviated from the population median. More precise estimations of the actual genomic copy numbers for (part of) the NSF gene locus, revealed copy numbers ranging from two to at least seven. Additionally, significant inter-population differences in the distribution of these copy numbers were observed. These data suggest that insight into absolute DNA copy numbers for loci exhibiting CNV is required to determine their potential contribution to normal phenotypic variation and, in addition, disease susceptibility.

Nine unknown rearrangements in 16p13.3 and 11p15.4 causing alpha- and beta-thalassaemia characterised by high resolution multiplex ligation-dependent probe amplification.

BACKGROUND: Approximately 80% of the alpha- and 10% of the beta-thalassaemias are caused by genomic deletions involving the alpha- and beta-globin gene clusters on chromosomes 16p13.3 and 11p15.5, respectively. Gap-PCR, Southern blot analysis, and fluorescent in situ hybridisation are commonly used to identify these deletions; however, many deletions go undetected using conventional techniques. METHODS: Patient samples for which no abnormalities had been found using conventional DNA techniques were analysed by a three colour multiplex ligation-dependent probe amplification assay. Two sets of 35 and 50 probes, covering a region of 700 kb of the alpha- and 500 kb of the beta-globin gene cluster, respectively, were designed to detect rearrangements in the alpha- and beta-globin gene clusters. RESULTS: In 19 out of 38 patient samples, we found 11 different alpha-thalassaemia deletions, six of which were not previously described. Two novel deletions leaving the alpha-globin gene cluster intact were found to cause a complete downregulation of the downstream alpha-genes. Similarly, 31 out of 51 patient samples were found to carry 10 different deletions involving the beta-globin gene cluster, three of which were not previously described. One involves the deletion of the locus control region leaving the beta-globin gene cluster intact. CONCLUSIONS: These deletions, which are not easily detected by conventional techniques, may have clinical implications during pregnancy ranging from mild to life threatening microcytic haemolytic anaemia in neonates. The approach as described here is a rapid and sensitive method for high resolution analysis of the globin gene clusters and for any region of the genome.

[Prevention of hereditary haemoglobinopathies in The Netherlands]. / Preventie van erfelijke hemoglobinopathieën in Nederland.

Haemoglobinopathies are defects that interfere with the synthesis of haemoglobin. Parents who are both healthy carriers (heterozygotes) may produce severely affected homozygous or compound heterozygous children who can be treated only symptomatically. Offering Dutch couples at risk the possibility of primary prevention is a matter of good healthcare and its organisation deserves priority. The prevention of haemoglobinopathy is based on the provision of information to potential carriers, carrier diagnostics and counselling, services that can in principle be provided by existing public health care institutions. Three moments at which the prevention of recessive diseases can be offered are the phase of preconception, the phase of early pregnancy (prospective primary prevention) and the postnatal phase at the time of a following pregnancy (retrospective primary prevention). By providing basic information and requesting laboratory tests for the diagnosis ofhaemoglobinopathy, the general practitioner plays a crucial role in primary prevention.

[Acute anaemia in a Vietnamese patient with alpha-thalassaemia and a parvovirus infection]. / Acute anemie bij een Vietnamese patiënt met alpha-thalassemie en een parvovirus-infectie.

A 14-year-old girl of Vietnamese descent with an unremarkable medical history presented with haemodynamic shock due to severe anaemia. This was caused by an aplastic crisis resulting from the combined effects of a Parvovirus infection and HbH disease. The HbH disease was a result of compound heterozygosity for the South East Asia (SEA) deletion and the Constant Spring mutation in the genes coding for alpha-globin chains (HbH/Hb Bart's). The girl had multiple blood transfusions and recovered. Family investigation revealed that, in addition to these 2 mutations in the alpha-globin gene, some family members also carried the 3.7-kb deletion of the alpha-globin gene, a mutation in the beta-globin gene resulting in HbE, and a novel mutation of unknown clinical significance in the beta-globin gene. This case demonstrates that essentially asymptomatic carriership of thalassaemia can have serious consequences when coupled with a concurrent infection.

Hemoglobin Tilburg: alpha 2-beta 2 73 (E 17) Asp----Gly. A new hemoglobin with reduced oxygen affinity.

A new hemoglobin variant has been found in a Dutch Caucasian girl and detected also in members of three generations of her family. This variant is characterized by the substitution of an aspartic acid at position 73 (E 17) of the beta-chain with a glycine residue. Hemoglobin Tilburg makes up to 42% of the total hemoglobin in the blood of the proposita, it is stable at the isopropanol test, and not associated with significant hematological abnormalities in heterozygous carriers. The oxygen dissociation curve of the purified variant, carried out at different pH values, shows a definite reduction of the affinity for oxygen and a normal alkaline Bohr effect. Three more hemoglobins with a single amino acid substitution at the same site have been previously described: Hb Korle-Bu (Asp----Asn), Hb Mobile (Asp----Val) and Hb Vancouver (Asp----Tyr). In all these proteins the affinity for oxygen is lowered to an extent which is variable and characteristic of each mutant. In this paper we discuss the possible mechanism responsible for the abnormal behaviour of hemoglobins substituted at beta 73.

Possible duplication of the hemoglobin alpha chain locus in sheep.

Only one type of alpha chain has been described so far in the hemoglobins of adult domestic sheep. A variant (Hb D) of the alpha chain, characterized by a substitution glycine leads to aspartic acid at position 15, has been described in Yugoslavian sheep. In this paper we report the identification of a second alpha chain (alpha 2), observed in several sheep when the globin was analyzed by CM-cellulose chromatography or the total hemolysate submitted to isoelectric focusing. The ratio of this chain to the usual one (alpha 1) in the globin of different animals is equal to either 1 : 2 or 1 : 4. The structural difference between alpha 1 and alpha 2 chains consists in the replacement of a leucine residue by an histidine in the position 113 or 114 of the polypeptide chain. Preliminary data on the frequency of the alpha 2 chain in eight domestic breeds indicate that this chain is fairly common, being present in 15 out of 40 animals examined. The results of breeding experiments between sheep of an appropriate alpha chain phenotype suggest the possibility of a duplication of the hemoglobin alpha locus in the Ovinae.

A complex haemoglobinopathy diagnosis in a family with both beta zero- and alpha (zero/+)-thalassaemia homozygosity.

The occurrence of point mutation alpha-thalassaemia and of complex combinations of haemoglobin defects is underestimated. Haemoglobinopathies, the most frequent monogenic recessive autosomal disorder in man, occur predominantly in Mediterranean, African and Asiatic populations. However, countries of immigration with a low incidence in the indigenous population, are now confronted with a highly heterogeneous array of imported defects. Furthermore, the occurrence of severe phenotypes is bound to increase in the near future because of the endogamous growth of the ethnical minorities and the lack of prevention. We describe an Afghan family in which both partners of a consanguineous relationship are carriers of a beta- as well as an alpha-thalassaemia determinant. The combination of defects was revealed by the in vitro measurement of the beta/alpha biosynthetic ratio and was characterised at the DNA level. The molecular defects involved are the Cd5(-CT), a Mediterranean beta zero-thalassaemia mutation, and the alpha 2(zero/+)-thalassaemia AATA(-AA) polyadenylation defect. The alpha-thalassemia defect is a rare RNA-processing mutant described only twice before in heterozygous form in Asian-Indian patients. The mutation suppresses the expression of a alpha 2 gene and reduces the expression of the less efficient, 3' located alpha 1 gene as well, inducing a near alpha zero-thalassaemia phenotype. This defect is now described for the first time in the homozygous condition in one of the children who, in addition to being homozygous for the alpha-thalassaemia point mutation, is also a carrier of the beta zero-thalassaemia defect. A previously described homozygous case of the alpha (zero/+)-thalassaemia condition, caused by a similar polyadenylation defect, was characterised by a severe HbH disease. However, the patient described here present at 7 years of age with severe caries, like his beta-thalassaemia homozygous brother but without hepatosplenomegaly, haemolysis or severe anaemia. The haematological analysis revealed 9.5 g/dl Hb; 5.4 x 10(12)/I RBC; 0.33 I/I PCV; 61 fl MCV; 17.6 pg MCH and 6.2% of HbA2. The biosynthetic ratio beta:alpha was 1.6 and no HbH fraction was detectable either on electrophoresis or as inclusion bodies. The parents reported no complications during pregnancy, at birth, or in the neonatal period in rural Afghanistan. We presume therefore that the counterbalancing effect induced by the co-existing beta-thalassaemia defect could have modified a potentially severe perinatal HbH disease into a strongly hypochromic but well compensated 'alpha zero-like heterozygous' thalassaemia phenotype. The risk of a severe HbH disease, could have been easily missed in this family which was referred because of a child affected with beta-thalassaemia major.

Purification and primary structure of ceratotoxin A and B, two antibacterial peptides from the female reproductive accessory glands of the medfly Ceratitis capitata (Insecta:Diptera).

In the present article we report the purification and the amino acid sequence of two antibacterial peptides present in the secretion of the female reproductive accessory glands of the dipteran insect Ceratitis capitata. Both peptides consist of 29 amino acid residues, are heat stable, strongly basic and differ from each other for the substitution of two amino acids. Their primary sequence and predicted secondary structure are related to other families of peptides known to have lytic and/or antibacterial activity. We propose the name ceratotoxins (from Ceratitis) for these antibacterial peptides.

Paediatric allogeneic bone marrow transplantation for homozygous beta-thalassaemia, the Dutch experience.

We reviewed the results of the Dutch paediatric bone marrow transplant (BMT) program for children receiving HLA-identical BMT for beta-thalassaemia major over an 18-year period. In all, 19 patients underwent a total of 21 transplants in our treatment centre between July 1984 and February 2002. Eight females (age 0.3-12 years; median 5 years) and 11 males (age 0.8-18 years; median 6 years) were included. Information, prospectively collected, included molecular defects, donor genotype, beta/alpha-globin expression rates, serum ferritin levels, hepato-splenomegaly, chelation history, virology screening, liver pathology together with post-transplant outcome inclusive of leucocyte chimerism. In total, 11 patients received standard busulphan/cyclophosphamide (Bu/Cy) conditioning, with or without ATG. Stable engraftment was seen in 5/11 with late rejection occurring in six patients. Of these, two children underwent a second successful SCT. For this group, overall event-free survival (EFS) and disease-free survival (DFS) were 90 (10/11) and 64% (7/11), respectively. The probability of rejection was 55%. Subsequent addition of melphalan to the conditioning regimen resulted in long-term stable engraftment in all patients with an EFS/DFS for this group of 90% (9/10). Treatment-related mortality, irrespective of conditioning, was low at 5% (1/19 patients). Veno-occlusive disease (VOD) occurred in 19% (4/21 transplants) and acute GvHD in 19% (4/21 transplants). Post-BMT beta/alpha synthetic ratio measurement monitored donor erythroid engraftment and predicted rejection with a return to transfusion dependency. Maintained full donor chimerism is indicative of stable engraftment both for leucocyte and erythroid lineages, whereas mixed donor chimerism is not. Our results emphasise the importance of the conditioning regimen and post-transplant chimerism surveillance predictive of rejection or long-term stable engraftment.

The quality of adolescent friendships: long-term effects?

While differing in etiological emphasis, a variety of theoretical perspectives seem to coalesce around the notion that youthful friendships are "good" for development. Sociometric studies have documented that low status youth are at risk for a variety of negative outcomes, but there has been little longitudinal research focused on the qualities of youths' relations with peers. We conducted interviews focusing on adolescents' relations with their friends with 942 adolescents in 1982. In 1992, follow-up interviews (N = 620) allowed us to determine whether level of intimacy with friends was associated with a range of adult outcomes, once sociodemographic characteristics and level of family intimacy were taken into account. Adolescents who reported greater levels of intimacy with friends do not, as adults, indicate that they have significantly higher self-esteem, better relations with their parents, or increased marital satisfaction. In addition, the level of intimacy is not related to adult reports of psychological distress, involvement in criminal activity, or use of violence against one's spouse. In contrast, sociodemographic characteristics and level of attachment to parents are related to many of these kinds of outcomes. We also discuss implications for attachment or relational perspectives on youthful friendship.

[From gene to disease; from hemoglobin genes to thalassemia and sickle cell anemia]. / Van gen naar ziekte; van hemoglobinegenen naar thalassemie en sikkelcelanemie.

Haemoglobinopathies are the commonest autosomal recessive diseases in men. Mutations on the alpha and beta genes clusters, located on chromosome 16 and 11 respectively, have been strongly selected in many populations by the increased chance of survival of carriers in areas infested with malaria tropica. Unfortunately many of these mutations in homozygous or compound heterozygous forms generate severe phenotypes such as sickle cell disease and beta-thalassaemia major. The population at risk for haemoglobinopathies is increasing in the industrialized areas of northern Europe. Without preventive measures a cumulative number of 1,000 severely affected patients can be expected in the Netherlands if information and carrier diagnostics are not efficiently offered at the GP level. A specialized laboratory for postnatal and prenatal diagnosis has been available in Leiden for more than 10 years now; however, couples at risk are only sporadically referred for counselling and/or prenatal diagnosis.

[The 'Anemia in the midwife practice' standard issued by the Royal Dutch Organisation of Midwives: a risk of not recognizing iron deficiency and hemoglobinopathy]. / De standaard 'Anemie in de eerstelijns verloskundige praktijk' van de Koninklijke Nederlandse Organisatie van Verloskundigen (KNOV): risico voor het niet onderkennen van ijzergebrek en hemoglobinopathie.

The standard entitled 'Anaemia in the midwife practice' issued by the Royal Dutch Organisation of Midwives presumes that the only reason for iron therapy in pregnancy is the prevention of adverse pregnancy outcome due to a low haemoglobin level. Pregnant women are screened for iron deficiency anaemia by means of sequential testing of haemoglobin and mean corpuscular volume (MCV). As a result only 10% of pregnant women will receive iron supplements. This practice will lead to a deterioration in the already low iron status of Dutch premenopausal women. As the haemoglobin reference values are lower than hitherto used, only severely anaemic women will be detected. Due to the low diagnostic accuracy of the MCV test the subsequent selection will be an arbitrary one. The standard sets the cut-off values for haemoglobin in black women at an even lower level, which will reduce the number of haemoglobinopathies detected in the immigrant population. The non-carriers in this group will run an increased risk of adverse pregnancy outcome if these cut-off values are used. We are strongly in favour of the measurement of haemoglobin, erythrocyte indices and ferritin in early pregnancy. In this way, iron deficiency, iron deficiency anaemia, anaemia due to other causes and haemoglobinopathies, the latter highly underestimated in the standard, can be detected.

[Combined alpha and beta thalassemia in a Chinese family in The Netherlands]. / Gecombineerde alpha- en beta-thalassemie bij een Chinese familie in Nederland.

In a Chinese family living in The Netherlands alpha 0- and beta-thalassaemia occur singly and in combined form. All members of the family are moderately anaemic and show the characteristic haematological abnormalities of thalassaemia carriers. The nature of the alpha 0-thalassaemia defect was shown at the molecular level to be a deletion of the South East Asian type, which removes about 20 kb of DNA spanning both alpha genes in cis. The chromosome carrying the beta-thalassaemia mutation was identified using RFLPs (restriction enzyme fragment length polymorphisms). The combined heterozygosity for alpha 0- and beta-thalassaemia results in a phenotype virtually indistinguishable from heterozygous beta-thalassaemia, except for the almost balanced globin chain synthesis.

Sickle cell anemia and α-thalassemia: a modulating factor in homozygous HbS/S patients in Oman.

We report the general phenotype severity and the hematological presentation in a cohort of 125 sickle cell anemia (SCA) patients with identical homozygous HbS/S genotype and categorized by identical ß(S) haplotype, both with and without alpha thalassemia. No clear general phenotype correlation was found when patients were compared regardless of the haplotype but overall, patients with homozygous alpha thalassemia (α-/α-) had the highest Hb, HCT, RBC and the lowest MCV, MCH and MCHC levels. When patients with identical haplotype were compared, the mildest hematological and clinical conditions were observed in patients of the Asian/Asian haplotype, also known as Arab-Indian haplotype, and carriers of α-thalassemia, suggesting an additional ameliorating effect of alpha thalassemia. In conclusion, our results show that alpha thalassemia improves the hematological conditions but amelioration of the general disease severity is only noticed when compared in cohorts of the same haplotype.

After the introduction into the national newborn screening program: who is receiving genetic counseling for hemoglobinopathies in the Netherlands?

OBJECTIVE: Universal newborn screening for hemoglobinopathies started in The Netherlands in 2007. Herewith severe conditions, such as sickle cell disease, ß-thalassemia major and hemoglobin H disease are putatively identified. Additionally, at least 1,800 carriers of hemoglobin variants associated with severe conditions in homozygote or compound heterozygote forms are identified yearly. Thus far, approximately 60 patients and 800 healthy sickle cell (HbS) carriers are reported each year among 180,000 newborns. Results are sent to the general practitioner with the recommendation to inform and diagnose both parents of the healthy carriers to exclude genetic risk, while patients and their parents are referred directly to a pediatrician. This study was performed to determine how often parents of identified carriers and affected newborns are seen in genetic centers for counseling. METHODS: In this retrospective study, we collected anonymized data from 7 of the 8 Dutch clinical genetic centers from January 1, 2007, until December 31, 2010. RESULTS: After an initial general increase in total counseling intakes, a decline was noticed in the third year, while the requests for prenatal diagnoses remained relatively stable. In 2007 and 2013, genetic counselors were asked for self-reported knowledge. They found hemoglobinopathy counseling complex, but by 2013, they indicated they had acquired sufficient knowledge on most hemoglobinopathy aspects. CONCLUSION: We could not observe a significant increase in genetic counseling for hemoglobinopathy after its introduction into newborn screening. Although 120 HbS carriers and 60 patients are expected to be born from couples at risk annually, only 33 at risk couples out of 540 families of diagnosed newborns received optimal care and information at a genetics center in 4 years.

Newborn screening for hemoglobinopathies using capillary electrophoresis.

This chapter reports the essential elements needed to understand basic laboratory diagnostics consisting of separation and measurement of the hemoglobin fractions. Although well established, basic diagnostics require some background and some degree of experience for application and interpretation. Last generation methods, consisting of automatic systems like high performance liquid chromatography and capillary electrophoresis (CE), allow high through put analysis in adults and newborns. Newborn screening using CE is presented in some details, using as an example the Capillarysâ Neonat Hb system (Sebia, France), as an upcoming alternative, explaining the method, the interpretation of the results, the objectives, the follow up, the advantages, and the pitfalls.

Strategies for basic laboratory diagnostics of the hemoglobinopathies in multi-ethnic societies: interpretation of results and pitfalls.

The consistent multi-ethnic migrations of the last decades have considerably changed the epidemiology of the hemoglobinopathies. Healthy carriers of these conditions are present today in many nonendemic parts of the world, and severely affected children are now born where these diseases were previously rare or unknown. Improving the competence in carrier diagnostics at the laboratory level is one of the first concerns when introducing management and primary prevention of the severe conditions in nonendemic areas. This review describes how and when carriers should be correctly diagnosed and informed. The essential technologies needed for basic carrier diagnostics in different situations are summarized in some detail, and interpretation of the results and a number of related problems are discussed. The role of the hematology laboratory is essential, particularly in nonendemic areas where the first line of health care is often insufficiently aware of hemoglobinopathy management. Carriers living in nonendemic areas can be appropriately diagnosed and informed regarding genetic risk and prevention by well-organized laboratories. Both basic and specialized diagnostics are needed for the correct treatment for the anemic carriers, for primary prevention in couples at risk and for state-of-the art care of severely affected patients.