Comprehensive Genomic Analysis Identifies a Diverse Landscape of Sideroblastic and Nonsideroblastic Iron-Related Anemias with Novel and Pathogenic Variants in an Iron-Deficient Endemic Setting

Inherited iron metabolism defects are possibly missed or underdiagnosed in iron-deficient endemic settings because of a lack of awareness or a methodical screening approach. Hence, we systematically evaluated anemia cases (2019 to 2021) based on clinical phenotype, normal screening tests (high-performance liquid chromatography, α gene sequencing, erythrocyte sedimentation rate, C-reactive protein, and tissue transglutaminase), and abnormal iron profile by targeted next-generation sequencing (26-gene panel) supplemented with whole-exome sequencing, multiplex ligation probe amplification/mitochondrial DNA sequencing, and chromosomal microarray. Novel variants in ALAS2, STEAP3, and HSPA9 genes were functionally validated. A total of 290 anemia cases were screened, and 41 (14%) enrolled for genomic testing as per inclusion criteria. Comprehensive genomic testing revealed pathogenic variants in 23 of 41 cases (56%). Congenital sideroblastic anemia was the most common diagnosis (14/23; 61%), with pathogenic variations in ALAS2 (n = 6), SLC25A38 (n = 3), HSPA9 (n = 2) and HSCB, SLC19A2, and mitochondrial DNA deletion (n = 1 each). Nonsideroblastic iron defects included STEAP3-related microcytic anemia (2/23; 8.7%) and hypotransferrenemia (1/23; 4.3%). A total of 6 of 22 cases (27%) revealed a non-iron metabolism gene defect on whole-exome sequencing. Eleven novel variants (including variants of uncertain significance) were noted in 13 cases. Genotype-phenotype correlation revealed a significant association of frameshift/nonsense/splice variants with lower presentation age (0.8 months versus 9 years; P < 0.01) compared with missense variants. The systematic evaluation helped uncover an inherited iron defect in 41% (17/41) of cases, suggesting the need for active screening and awareness for these rare diseases in an iron-deficient endemic population.

X-linked sideroblastic anaemia due to ALAS₂ mutations in the Netherlands: a disease in disguise

BACKGROUND

X-linked sideroblastic anaemia (XLSA; OMIM#300751) is the most common inherited form of sideroblastic anaemia and is associated with several mutations in the erythroid specific 5-aminolevulinate synthase gene (ALAS₂). This gene encodes for aminolevulinic acid synthase 2 (ALAS₂), the catalytic enzyme involved in the first en rate-limiting step of haem biosynthesis.1-3 The disorder is characterised by mostly mild hypochromic microcytic anaemia with bone marrow ring sideroblasts. Even untransfused patients with mild or no anaemia are at risk for severe systemic iron overload due to ineffective erythropoiesis. To date, 61 different ALAS₂ mutations have been reported in 120 families with XLSA. Descriptions of molecularly confirmed case series from the Netherlands, however, are lacking.

METHODS

We reviewed age of presentation, clinical and biochemical features, ALAS₋₂ defects and treatment characteristics of 15 Dutch patients from 11 unrelated families diagnosed with XLSA.

RESULTS AND CONCLUSIONS

In one family a novel pathogenic c.1412G>A (p.Cys471Tyr) mutation was found. All other families shared the previously described c.1355G>A (p.Arg452His) mutation. Haplotype analysis in seven probands with the p.Arg452His mutation strongly suggests that six of them were ancestrally related. Nevertheless, their phenotype was very different. Our patients illustrate the phenotypical heterogeneity in the presentation of XLSA patients, the effectiveness of treatment regimens and the various pitfalls associated with the diagnosis, follow-up and treatment of the disease. A timely diagnosis avoids unnecessary investigations and allows adequate treatment that can prevent systemic iron load with subsequent severe life-threatening complications. Therefore, we suggest considering XLSA in both male and female patients with unexplained iron overload and÷or (mild) microcytic anaemia, also at older age.

Primary myelodysplastic syndrome in Jordan: a single-centre experience

OBJECTIVE

Study of the disease patterns and clinical evaluation of myelodysplastic syndrome (MDS).

SUBJECTS AND METHODS

A retrospective analysis was carried out on 85 patients, with MDS who were followed up over a period of 23 years at Jordan University Hospital, Amman, Jordan. Cases were analyzed according to the French, American and British Classification.

RESULTS

Of the 85 patients, 42 (49.4%) were females and 43 (50%) males; mean age was 59 +/- 19 years (range 18-88). Most subtypes found in patients were refractory anemia (RA) in 27 (31.8%) and RA with excess blasts (RAEB) in 28 (32.9%). Adverse prognostic indicators were RAEB subtype and requirement for blood transfusion.

CONCLUSION

Our findings showed that MDSs appeared at a younger age and tended to be of the aggressive subtype. Chronic myelomonocytic leukemia subtype seemed to appear dominantly in men.

Onset of X-linked sideroblastic anemia in the fourth decade

We report the case of a 40-year female who manifested late onset, pyridoxine-refractory X-linked sideroblastic anemia, heterozygous for the first described frameshift ALAS2 mutation, CD506-507 (-C). On presentation she had macrocytic anemia with severe iron overload.

Myelopathies during the course of multiple myeloma

BACKGROUND

The development of acute non-lymphoblastic leukaemia (ANLL) or myelodysplastic syndromes (MDS) secondary to treatment of multiple myeloma (MM) is well known. In some cases the simultaneous appearance of MM and ANLL has been described.

METHODS

In this series the simultaneous appearance of MM and various myelopathies in 91 untreated patients with MM, and the development of myelopathies during the course of the disease in 72 treated patients were studied.

RESULTS

Simultaneous appearance of MM (IgA/lambda) and refractory anaemia with ring sideroblasts (RAS) was observed in one case (1.1%). Development of myelopathies in treated patients with MM was found in 4 out of 72 cases (cumulative risk at 8 years 28.3%). In one case (IgG/lambda MM) a myeloproliferative disorder (MPD) developed 6 years after the initial diagnosis. Cytogenetic analysis was normal. In the second patient (IgG/k MM) a similar MPD was observed 5 years after the initial diagnosis. The karyotype was 46, XX, -5 + t (20;?). The third patient with lambda light chain disease developed RAS 11 months after the initial diagnosis. The karyotype was 46, XY/hypodiploidy + M. Finally, the fourth case (IgG/k MM) developed ANLL (M4) 28 months after the initial diagnosis and the karyotype was 45, XX, -7, t(1;3).

CONCLUSIONS

The simultaneous appearance of MM and various myelopathies is unusual and probably represents a neoplastic transformation of a single progenitor in both lymphoid and myeloid malignancies. On the contrary, the development of myelopathies during the course of treated patients is a common phenomenon. The time of development and the cytogenetic findings strongly suggest that they are related to treatment with cytostatics.

Primary acquired sideroblastic anemia and myelodysplastic syndrome from a geriatric point of view

The median age of occurrence of primary acquired sideroblastic anemia is 74.4 years, with a range of 12 to 96 years (calculated from 452 cases). Of 445 cases, 60.4% were male, and 39.6% female. Not only primary acquired sideroblastic anemia, but the entire myelodysplastic syndrome must be considered as a disease of old age.

Nutritional anemias in the English-speaking Caribbean: a review of the literature

A review of the published literature on nutritional anemias in the English-speaking Caribbean was carried out. Published articles on the subject are few in number and are concentrated in the larger islands such as Jamaica and Trinidad. Nutritional anemias are most prevalent among women of childbearing age. Iron and folate deficiencies and, to a much lesser extent, protein deficiency resulting from insufficient dietary intakes of these nutrients are the major nutritional factors contributing to this anemia.