Microcytosis is commonly encountered in primary care. Among patients with normal iron stores or compatible family history, hemoglobin electrophoresis, traditionally performed with gel electrophoresis and now through combination capillary electrophoresis/high-performance liquid chromatography, can diagnose thalassemic disorders or, rarely, a hemoglobinopathy. We present a case of an incidentally discovered microcytosis in a 34-year-old male patient where the workup led to a diagnosis of Hemoglobin S with Hereditary Persistence of Fetal Hemoglobin (HbS-HPFH syndrome). The diagnosis led providers to re-evaluate the patient's chronic hip pain, upon which the patient was found to have bilateral osteonecrosis of the femurs. Microcytosis is a lab abnormality that is often asymptomatic and, therefore, may be ignored or overlooked. When encountering microcytosis in primary care, it is important to identify the etiology using a brief, targeted approach. This may directly impact management and can prove helpful when considering future complaints of the patient.

Beta-hemoglobinopathies are the most common genetic disorders worldwide, caused by a wide spectrum of mutations in the β-globin locus, and associated with morbidity and early mortality in case of patient non-adherence to supportive treatment. Allogeneic transplantation of hematopoietic stem cells (allo-HSCT) used to be the only curative option, although the indispensable need for an HLA-matched donor markedly restricted its universal application. The evolution of gene therapy approaches made possible the ex vivo delivery of a therapeutic β- or γ- globin gene into patient-derived hematopoietic stem cells followed by the transplantation of corrected cells into myeloablated patients, having led to high rates of transfusion independence (thalassemia) or complete resolution of painful crises (sickle cell disease-SCD). Hereditary persistence of fetal hemoglobin (HPFH), a syndrome characterized by increased γ-globin levels, when co-inherited with β-thalassemia or SCD, converts hemoglobinopathies to a benign condition with mild clinical phenotype. The rapid development of precise genome editing tools (ZFN, TALENs, CRISPR/Cas9) over the last decade has allowed the targeted introduction of mutations, resulting in disease-modifying outcomes. In this context, genome editing tools have successfully been used for the introduction of HPFH-like mutations both in HBG1/HBG2 promoters or/and in the erythroid enhancer of BCL11A to increase HbF expression as an alternative curative approach for β-hemoglobinopathies. The current investigation of new HbF modulators, such as ZBTB7A, KLF-1, SOX6, and ZNF410, further expands the range of possible genome editing targets. Importantly, genome editing approaches have recently reached clinical translation in trials investigating HbF reactivation in both SCD and thalassemic patients. Showing promising outcomes, these approaches are yet to be confirmed in long-term follow-up studies.

To report the diagnostic challenges of newborn screening for abnormal haemoglobins. Cord blood samples from 13 hospitals in southwest Jamaica taken in 2008-2019. Blood spots, collected from the umbilical cord, were analysed by high pressure liquid chromatography (HPLC) to reveal phenotypes for HbSS and HbCC, but genotype confirmation may require parental studies or gene sequencing. Such cases that were successfully traced were analysed in this follow-up study. HPLC screening of 121,306 samples detected HbAS in 11,846 (9.8%), HbAC in 4508 (3.7%) and other electrophoretic abnormalities in 1090 babies. Among 101 previously unconfirmed cases, 34/90 (38%) with HPLC evidence of a HbSS phenotype had other genotypes, and 7/11 (64%) with a HbCC phenotype had other genotypes. Syndromes from the interaction of β thalassaemia occurred in 112 babies (85 with HbS, 27 with HbC) and of genes for hereditary persistence of fetal haemoglobin (HPFH) in 18 (12 with HbS, 6 with HbC). Variants other than HbS and HbC occurred in 270 babies, 16 in combination with either HbS or HbC, and 254 as traits. Most variants are benign even when inherited with HbS, although HbO Arab, HbD Punjab, or Hb Lepore Washington, which occurred in 6 cases, may cause sickle cell disease. Genes for β thalassaemia and HPFH are common in western Jamaica and when associated with HbS may present diagnostic challenges in newborns, as HbF and HbA2 have not reached diagnostic levels. Family and DNA studies may be necessary for genotype confirmation.

Red blood cell exchange transfusion may be beneficial and should be considered in the early management of patients with sickle cell disease and COVID-19 to prevent the need for intubation and intensive care unit admission due to respiratory distress.

Fetal hemoglobin (HbF) is a physiologic protein tetramer that is crucial for a developing fetus to survive in utero. Maternal hemoglobin has a relatively lower affinity for oxygen, and thus allows for an efficient transfer of oxygen from maternal to fetal blood. In addition to fulfilling a critical physiologic role, HbF is also known to alleviate symptoms of sickle-cell disease (SCD). The concentration of HbF depends on several factors. HbF is elevated in inherited conditions, such as hereditary persistence of HbF, hereditary spherocytosis, and thalassemia. The level of HbF is also increased in acquired states, such as pregnancy, aplastic anemia, thyrotoxicosis, hepatoma, myeloproliferative disorders, or hypoplastic myelodysplastic syndrome. It has been identified that some genetic loci have significant influence on HbF levels. The XmnI polymorphism, the HMIP locus, and the BCL11A gene are responsible for 45% of variations in HbF levels. Although SCD has been well described in the subpopulations of Africa, it is less common in the subpopulations of India. We describe a case of SCD, in which a patient with high HbF level presented at a very late age (27 years old). We presume the patient's inherently elevated HbF levels were able to compensate for the hypoxic episodes associated with SCD. The onset of symptoms was delayed as a result of elevated HbF levels.