Limb defects in homozygous alpha-thalassemia: report of three cases

An international registry of survivors with Hb Bart's hydrops fetalis syndrome

Hemoglobin (Hb) Bart's hydrops fetalis syndrome (BHFS) resulting from α0-thalassemia is considered a universally fatal disorder. However, over the last 3 decades, improvements in intrauterine interventions and perinatal intensive care have resulted in increasing numbers of BHFS survivors. We have initiated an international registry containing information on 69 patients, of which 31 are previously unpublished. In this perspective, we analyze the available clinical information to document the natural history of BHFS. In the future, once we have accrued sufficient cases, we aim to build on this study and provide information to allow counseling of at-risk couples. To date, 39 patients have survived beyond the age of 5 years, 18 of whom are now older than 10 years. Based on the available cases, we find evidence to suggest that intrauterine therapy provides benefits during the perinatal and neonatal period; however, it may not provide additional benefits to long-term growth and neurodevelopmental outcomes. Growth retardation is a major adverse long-term outcome among BHFS patients with ∼40% being severely affected in terms of weight and ∼50% in terms of height. There is also an increased risk of neurodevelopmental delay as we find 20% (11/55) of BHFS survivors suffer from a serious delay of ≥6 months. Most patients in the registry require lifelong transfusion and often have associated congenital abnormalities and comorbidities. This perspective is a first step in gathering information to allow provision of informed counseling on the predicted outcomes of affected babies.

In Utero diagnosis and management of a fetus with homozygous α-Thalassemia in the second trimester: a case report and literature review

Alpha thalassemia with the absence of 4 α-globin genes leads to fetal hydrops and fetal death from anemia. Historically considered a lethal condition, optimal in utero management of homozygous α-thalassemia is unclear. A fetus of Filipino descent at 26 weeks gestation presented with ultrasound evidence of anemia. Cordocentesis confirmed anemia and homozygous α-thalassemia (--/--). Intrauterine transfusion corrected anemia but fetal growth restriction and oligohydramnios persisted. Intrauterine exchange transfusion improved hemoglobin parameters, fetal growth, and oligohydramnios. The late preterm infant was delivered with classic limb reduction defects. Hemoglobin Bart's is nonfunctional for oxygen transport, and intrauterine exchange transfusion may be effective first-line therapy and further investigation is warranted.

Survival of homozygous alpha-thalassemia with aplasia/hypoplasia of phalanges and jejunal atresia

We report a case of survival of homozygous alpha-thalassemia with aplasia/hypoplasia of phalanges and jejunal atresia. The occurrence of these malformations is consistent with the postulation that intra-uterine hypoxia due to the presence of hemoglobin Bart's (Hb Bart's) is the causative factor for the development of these malformations. There were two pitfalls in diagnosis: normal spun hematocrit level despite a low hemoglobin level and absence of hydropic features. Our case illustrated that nitric oxide and high frequency ventilation were ineffective in ameliorating persistent pulmonary hypertension of newborn until exchange transfusion was done replacing Hb Bart's with normal hemoglobin.

Limb defects in a fetus with homozygous alpha-thalassemia

A fetus with homozygous alpha-thalassemia (alpha-thal) who displayed limb reduction defects is described. These kinds of congenital anomalies should be surveyed by sonography in at-risk pregnancies and included in genetic counseling prior to in utero fetal therapy.

Prenatal two- and three-dimensional ultrasound diagnosis of limb reduction defects associated with homozygous alpha-thalassemia

OBJECTIVES

We present the prenatal two-dimensional (2D-) and three-dimensional ultrasound (3D-US) diagnosis of limb reduction defects associated with homozygous alpha-thalassemia and a review of the literature.

METHODS

At 17 weeks' gestation, amniocentesis was performed for cytogenetic and molecular studies, and 2D- and 3D-US examinations were made for evaluation of the fetal malformations.

RESULTS

Amniocentesis revealed a 46,XY karyotype and molecular analysis of the amniocytes showed that the fetus was homozygous for the Southeast Asian deletion (--SEA/--SEA). 2D-US examination revealed bilateral ventriculomegaly, brachycephaly, pleural effusion, digital deficiency and hypoplasia of the right foot, and digital deficiency of the left foot. 3D-US confirmed the distal limb reduction defects.

CONCLUSIONS

When the fetus is at risk for homozygous alpha-thalassemia, 2D- and 3D-US examinations are useful for prenatal detection of the associated limb reduction defects. Prenatal identification of the possible association with limb reduction defects is important for parental counseling and decision-making when intrauterine fetal therapy is an option.

Neurodevelopmental outcome and haematological course of a long-time survivor with homozygous alpha-thalassaemia: case report and review of the literature

AIM

Homozygous alpha-thalassaemia, also called haemoglobin (Hb) Bart's hydrops fetalis, has been thought to be a lethal condition. Due to prenatal diagnosis and intrauterine blood transfusions, a few patients with Hb Bart's hydrops fetalis have survived. This fact raises the urgent questions of clinical management and appropriate follow-up of these patients, both of which are addressed in this article.

METHODS

We report on a 6.5-y-old patient with homozygous alpha-thalassaemia and review the literature of 13 other survivors published to date. Transfusion requirements were evaluated and the rate of liver iron accumulation was assessed by biomagnetic liver susceptometry before and after institution of iron-chelating therapy. Psychometric evaluation was carried out using Munich's Functional Development Test, the Columbia Mental Maturity Scale, the Kaufman Assessment Battery for Children, and the Peabody Picture Vocabulary Test.

RESULTS

Our patient had significant delay of psychomotor development. Psychometric evaluation at the age of 5 y revealed an IQ of 85 and an intellectual level of a 4-y-old child. Early tissue iron overload was seen, but a negative iron balance was achieved after institution of desferrioxamine treatment at dosages used for beta-thalassaemia.

CONCLUSION

Homozygous alpha-thalassaemia should no longer be regarded as a lethal condition. Early intervention during pregnancy and careful haematological as well as neuropsychological follow-up was able to provide long-term survival and good life quality in our patient.

Vascular-type disruptive defects in fetuses with homozygous α-thalassemia: report of two cases and review of the literature

BACKGROUND

The thalassemias are an inherited group of heterogeneous anemias in which one or more of the globin chains in the hemoglobin tetramer are absent. Fetuses with homozygous alpha-thalassemia, which is particularly prevalent in people of Southeast Asian extraction, experience deficient alpha-globin chain synthesis and cannot produce hemoglobin F (the primary fetal hemoglobin after 8 weeks' gestation). Instead, they produce an anomalous hemoglobin, hemoglobin Bart's, with an unusually high affinity for oxygen, leading to profound anemia and tissue hypoxia.

METHODS AND RESULTS

Here we report on two fetuses with homozygous alpha-thalassemia who displayed structural defects of a vascular disruptive type. Both fetuses demonstrated limb anomalies, including terminal transverse limb deficiencies, and one fetus was found to have a brain malformation consisting of a neuronal migrational defect. The limb anomalies and suspected brain malformation were detected on prenatal ultrasound prior to confirmation of the diagnosis of alpha-thalassemia in one case; in the other case prenatal records were not available. While microcephaly, hydrocephalus, and retarded brain growth have been rarely reported in association with homozygous alpha-thalassemia, this is the first report of a true brain malformation in an affected fetus. Limb anomalies, on the other hand, appear to be more frequent. Recently, aggressive in utero and postnatal therapies for homozygous alpha-thalassemia have been attempted with some success.

CONCLUSIONS

Our cases and those from the medical literature suggest that couples need to be counseled about the risks of congenital anomalies of a vascular disruptive type in affected fetuses. Furthermore, data from the literature suggests that in utero therapy may not significantly decrease these risks as such anomalies may be present prior to the institution of therapy. In addition, in hydropic infants with vascular disruptive defects, especially in those of Southeast Asian origin, homozygous alpha-thalassemia should be suspected as a likely etiology.

Hydrops fetalis caused by homozygous alpha-thalassemia and Rh antigen alloimmunization: report of a survivor and literature review

Hematologic causes of hydrops fetalis include homozygous alpha-thalassemia and immune hemolytic anemias. We report the case of a boy with hydrops fetalis who had homozygous alpha-thalassemia and alloimmune hemolytic anemia due to anti-E and anti-C blood group antibodies. He received intrauterine red blood cell transfusions and postnatal chronic transfusion with iron chelation therapy. A non-myeloablative sibling stem cell transplant failed. He is now 5 years and 6 months of age, hypothyroid with short stature, but in overall good health. He is one of the oldest reported homozygous alpha-thalassemia survivors and, to our knowledge, the only survivor with immune- and nonimmune-induced hydrops fetalis.

Hemoglobinopathies in pregnancy

Hemoglobinopathies represent a unique set of genetic disorders. Formerly, many affected individuals did not survive to childbearing age. Affected women now commonly reach childbearing age and desire pregnancy. Successful pregnancy is possible in many cases with carefully coordinated obstetric and medical management. Genetic screening and prenatal diagnosis is an important aspect of prenatal care in these disorders. DNA mutation analysis offers rapid and accurate fetal diagnosis. Pregnancy also offers a unique situation in that cord blood has become a valuable source of stem cells for transplant. This allows the potential role of the unaffected fetus as a donor for affected siblings. In addition, it was proposed that the fetus may be able to act as a donor of stem cells for an affected mother. Despite current screening recommendations,many couples are not aware that they are carriers; it is common for a child to be born with an unexpected, serious hemoglobinopathies. For this reason, newborn screening programs have been introduced in most high-risk areas. Early diagnosis can facilitate implementation of proper preventive health measures, education of the parents regarding their carrier status, and provide the child with ongoing comprehensive care.

Severe terminal transverse limb reduction defects in homozygous Southeast-Asian alpha-thalassaemia-1

A rare occurrence of a homozygous a-thalassaemia fetus with severe terminal transverse limb reduction defects involving all limbs is reported. When prenatal testing, either by DNA analysis or haemoglobin electrophoresis, indicating a fetus with homozygous alpha-thalassaemia, a complete sonographic survey of fetal limbs is mandatory, and terminal transverse limb reduction defects should be included in genetic counselling prior to in utero fetal therapy.

Limb reduction defects as the sonographic manifestation of hemoglobin Bart's disease at 10 weeks of gestation

Fetuses affected by hemoglobin Bart's disease are anemic and hypoxic from the first trimester. They develop cardiac and placental enlargement and have a high incidence of limb reduction defects and hypospadias. We present a fetus at risk for hemoglobin Bart's disease with multiple limb reduction defects detected at 10 weeks of gestation, which allowed a strong presumptive diagnosis of hemoglobin Bart's disease to be made at the time of ultrasound examination. The limb defects were verified by direct visualization via needle embryoscopy. The present case suggests that sonographic identification of limb reduction defects may be a specific marker of hemoglobin Bart's disease at 10 weeks.

Changing outcome of homozygous alpha-thalassemia: cautious optimism

Only a few long-term survivors of homozygous alpha-thalassemia, a usually fatal condition, have been reported. The authors present a surviving infant with this disorder and discuss the complications, treatments, and implications of this genetic hemoglobinopathy. The child had no antenatal intervention and has been treated with regular transfusions. She has had normal growth and development and is currently 2.5-years-old. A literature review of survivors with Bart hemoglobinopathy reveals an intense perinatal course and a great prevalence of congenital urogenital and limb defects. Advances in antenatal diagnosis, intrauterine intervention, and postnatal treatments have resulted in extended survival of children with congenital defects that until recently were considered invariably fatal. Transfusion and chelation therapy and bone marrow transplantation provide long-term treatment and potential curative options.

Alpha-thalassaemia

alpha-Thalassaemias are genetic defects extremely frequent in some populations and are characterized by the decrease or complete suppression of alpha-globin polypeptide chains. The gene cluster, which codes for and controls the production of these polypeptides, maps near the telomere of the short arm of chromosome 16, within a G + C rich and early-replicating DNA region. The genes expressed during the embryonic (zeta) or fetal and adult stage (alpha 2 and alpha 1) can be modified by point mutations which affect either the processing-translation of mRNA or make the polypeptide chains extremely unstable. Much more frequent are the deletions of variable size (from approximately 3 to more than 100 kb) which remove one or both alpha genes in cis or even the whole gene cluster. Deletions of a single gene are the result of unequal pairing during meiosis, followed by reciprocal recombination. These unequal cross-overs, which produce also alpha gene triplications and quadruplications, are made possible by the high degree of homology of the two alpha genes and of their flanking sequences. Other deletions involving one or more genes are due to recombinations which have taken place within non-homologous regions (illegitimate recombinations) or in DNA segments whose homology is limited to very short sequences. Particularly interesting are the deletions which eliminate large DNA areas 5' of zeta or of both alpha genes. These deletions do not include the structural genes but, nevertheless, suppress completely their expression. Larger deletions involving the tip of the short arm of chromosome 16 by truncation, interstitial deletions or translocations result in the contiguous gene syndrome ATR-16. In this complex syndrome alpha-thalassaemia is accompanied by mental retardation and variable dismorphic features. The study of mutations of the 5' upstream flanking region has led to the discovery of a DNA sequence, localized 40 kb upstream of the zeta-globin gene, which controls the expression of the alpha genes (alpha major regulatory element or HS-40). In the acquired variant of haemoglobin H (HbH) disease found in rare individuals with myelodysplastic disorders and in the X-linked mental retardation associated with alpha-thalassaemia, a profound reduction or absence of alpha gene expression has been observed, which is not accompanied by structural alterations of the coding or controlling regions of the alpha gene complex. Most probably the acquired alpha-thalassaemia is due to the lack of soluble activators (or presence of repressors) which act in trans and affect the expression of the homologous clusters and are coded by genes not (closely) linked to the alpha genes. The ATR-X syndrome results from mutations of the XH2 gene, located on the X chromosome (Xq13.3) and coding for a transacting factor which regulates gene expression. The interaction of the different alpha-thalassaemia determinants results in three phenotypes: the alpha-thalassaemic trait, clinically silent and presenting only limited alterations of haematological parameters, HbH disease, characterized by the development of a haemolytic anaemia of variable degree, and the (lethal) Hb Bart's hydrops fetalis syndrome. The diagnosis of alpha-thalassaemia due to deletions is implemented by the electrophoretic analysis of genomic DNA digested with restriction enzymes and hybridized with specific molecular probes. Recently polymerase chain reaction (PCR) based strategies have replaced the Southern blotting methodology. The straightforward identification of point mutations is carried out by the specific amplification of the alpha 2 or alpha 1 gene by PCR followed by the localization and identification of the mutation with a variety of screening systems (denaturing gradient gel electrophoresis (DGGE), single strand conformation polymorphisms (SSCP)) and direct sequencing.