Nabais Sa-de Vries syndrome (NSDVS) is a rare autosomal dominant disease first time reported in 2020 [1]. The syndrome is caused by heterozygous de novo missense mutations in speckle-type pox virus and zinc finger protein (SPOP) on chromosome 17q21. It is divided into two forms (NSDVS type 1; OMIM: 618828 and NSDVS type 2; OMIM: 618829) based on the consequence of the mutation involved [2,3]. Nabais Sa-de Vries syndrome type 1 is characterized by global developmental delay which is apparent from infancy, variable behavioral problems, mi-crocephaly, and dysmorphic facial characteristics, includ-ing a round face, small palpebral fissures, highly arched eyebrows, and short nose [1].

Protein homeostasis plays an important function in intracellular biological mechanism. The ubiquitin-protea-some pathway (UPP) works in intracellular protein homeostasis by regulating the breakdown of many proteins. The speckle-type BTB/POZ protein, encoded by the SPOP (OMIM#602650), promotes target protein degradation via UPP [4]. The SPOP gene plays a role in tumor suppres-sion by destabilizing downstream oncoproteins in some malignancies i.e., prostate cancer. However, in other malignancies such as renal and endometrial cancers, SPOP has an oncogenic role [5]. Although many clinical features are reported in association with Nabais Sa-de Vries syndrome, however its association with hematological manifestations and more importantly with iron refractory iron deficiency anemia as seen in our patient has not been reported in previous studies.

The HBB gene encodes beta-globin and is located on chromosome 11 [6]. Mutations in the HBB gene may lead to one of the most common hematological autosomal recessive diseases worldwide, beta-thalassemia which is caused by the reduced (beta+; β+) or absent (beta0; β0) synthesis of the beta globin chains of the hemoglobin tetramer. Based on various clinical and hematological severity, three conditions are recognized, i.e., the beta-thalassemia carrier, thalassemia intermedia, and thalas-semia major [6-8]. Differences in genotype, degree of globin chain imbalance, and amount of transfusion (ade-quate, inadequate or no transfusion) defined the wide spectrum of clinical severity. Common clinical features of beta-thalassemia are microcytic hypochromic anemia, jaundice, hepatosplenomegaly, hypersplenism, growth retardation, pubertal failure, extramedullary hematopoiesis, and bone deformities [8-11].

In this study, we report a 4-year-old girl who presents with microcephaly, a wide and thick arched eyebrow, a prominent and wide nasal bridge, a wide and bulbous nasal tip, micrognathia, and pointed chin. She also had microcytic hypochromic anemia without organomegaly. Genetic study was offered, which confirmed the presence of both SPOP and hemoglobin (HBA and HBB) gene mu-tations. She has clinical features of NSDVS1 and beta thalassemia along with resistant iron deficiency anemia.

The concurrence of the above two genetic mutations and resistant iron deficiency anemia has not been reported previously thus further studies are needed to better understand the mechanisms of the associated clinical manifestations and disease course involved.

Written informed consent was obtained from the parents for the publication of the photographs and clinical information presented in this report.

Our patient, now a 4-year-old girl, was the second live child born at term to nonconsanguineous parents, a 36-year-old father, and a 34-year-old mother with an unremarkable gestational course. The mother had a history of two prior miscarriages due to unknown reasons. None of the family members have NSDVS or other syndromes. Father was diagnosed as beta-thalassemia minor while mother and siblings do not have any hematological dis-eases. Birth weight, length, and head circumference were 2.8 kg (25th percentile), 48.2 cm (25th percentile), and 33 cm (10th percentile) respectively. Perinatal events were significant for hospitalization after birth for 3 days for respiratory issues as well as neonatal jaundice requiring phototherapy then discharged home in stable condition.

On examination, she had microcephaly, a long face, a wide and thick arched eyebrow, widely spaced eyes, a prominent and wide nasal bridge, a wide and bulbous nasal tip, large size ears, and prominent antitragus, micrognathia, and a pointed chin (Fig. 1). Her current growth parameter was, weight 16 kg (50th percentile), height 109 cm (90th percentile), and head circumference 46 cm (<3rd percentile). Abdominal examination was unremark-able including no hepatosplenomegaly. Her neurological assessment identified a hyperactive child with poor interaction and understanding, and speech delay.

Figure 1. Craniofacial dysmorphisms. Note microcephaly, a long face, a wide and thick arched eyebrow, widely spaced eyes, a prominent and wide nasal bridge, a wide and bulbous nasal tip, large size ears, prominent antitragus, and a pointed chin.

At 2 months of age, she developed two seizure-like episodes, however, her neuroimaging and electroencephalogram testing were normal. Her CBC (complete blood count) showed low Hb level (Hb 8.9 g/dL), MCV (69.6 fL), MCH (21.7 pg) and RBC (4.11×10⁶/mL), and high RDW (17.2%) and Mentzer index (16.9) with a corrected reticulocyte count of 3.7%. However, her platelet counts white blood cell, and differential count were normal. Peripheral blood smear findings confirmed the hypochromic microcytic anemia. She was investigated for iron deficiency anemia and initial results showed normal iron stores (iron 8.7 mmol/L, TIBC 42 mmol/L, transferrin saturation 20.7%). Hemoglobin electrophoresis was also done, and beta thalassemia trait was suspected (HB-A 74.5%, HB-F 21.3%, HB-A2 4.2%), however, repeated hemoglobin electrophoresis was advised because of age. Chest x-ray was unremarkable and echocardiography has revealed normal anatomy, size, and good contractility.

At the age of 12 months, laboratory findings showed persistence of hypochromic microcytic anemia (CBC: Hb 8.4 g/dL, MCV 48.1 fL, MCH 15.7 pg, RBC 5.37×10⁶/mL, RDW 23.2% and Mentzer index 9) with normal serum iron (11.2 mmol/L), slightly elevated TIBC (TIBC 86 mmol/L) and low transferrin saturation (13%). At 18 months of age her laboratory showed worsening of anemia (Hb 7.7 g/dL), although her MCV (48.6 fL), MCH (15.8 pg), and RDW (25.4%) remained stable. However, her repeated iron study was suggestive of iron depletion (serum iron 4.4 mmol/L). Peripheral blood smear (Fig. 2A) showed a picture of hypochromic microcytic anemia. Repeated hemoglobin electrophoresis at that time was again suggestive of beta thalassemia trait (HB-A 94.6%, HB-F 1.6%, HB-A2 3.8%).

Figure 2. Peripheral smear and bone marrow findings. (A) Peripheral blood smear (50× oil immersion) showing hypochromic microcytic red cells and nucleated red cell. (B) Bone marrow giemsa staining (10×) showing erythroid hyperpla-sia. (C) Bone marrow giemsa stain-ing (50× oil immersion) showing erythroid hyperplasia. (D) Perl’s iron stain on bone marrow aspirate (4×) showing absence of storage iron.

Whole exome sequencing (WES) was requested and identified the heterozygous variant c.977A>G p. (Asn326Ser) in SPOP gene (OMIM:602650) and heterozygous variant c.93-22_95del p.? in HBB gene (OMIM:141900). Molecular genetic analysis of the hemoglobin genes, revealed that the patient carries the β° mutation c.93-22_95del p.? in the HBB gene in one allele (heterozygous) consistent with β-thalassemia trait. Additionally, the heterozygous common deletion −α3.7 of the α-globin cluster (−α3.7/αα) was detected (Table 1).

Table 1 . Summary of genetic information.

Gene (isoform)	Phenotype/MIM number	Mode of inheritance	Variant	Zygosity	Classification
SPOP (NM_001007226.1)	Nabais Sa-de Vries syndrome 618828 618829	Autosomal dominant	c.977A>G p. (Asn326Ser) chr17:47679230	Heterozygous	Variant of uncertain significance
HBB (NM_000518.5)	β-Thalassemia 613985	Autosomal recessive	c.93-22_59del p.?	Heterozygous	Pathogenic
HBA	α-Thalassemia	Autosomal recessive	Common deletion (−α3.7/αα)	Heterozygous	Pathogenic

MIM, Mendelian Inheritance in Man; SPOP, speckle-type pox virus and zinc finger protein; HBB, hemoglobin subunit beta; HBA, hemoglobin subunit alpha..

At the age of 24 months, CBC showed (Hb 6.4 g/dL, MCV 35.4 fL, MCH 13.7 pg, RBC 5.16×10⁶/mL, RDW 29.6% and Mentzer index 10) with low serum iron and low trans-ferrin saturation (TS) and normal TIBC (iron 2.3 mmol/L, TS 3.5%, TIBC 65 mmol/L). Bone marrow biopsy showed erythroid hyperplasia (Fig. 2B and 2C) and absent iron storage (Fig. 2D). During this period, she received blood transfusions multiple times (Fig. 3), mostly every 1-2 months. Oral iron therapy was initiated but without improvement despite of full dose of ferrous sulphate (6 mg/kg/day) and compliance. Work up for resistant iron deficiency anemia was also initiated, showed no gastrointestinal bleeding or other indefinable causes.

Figure 3. Summary of serial complete blood count and blood transfusions. Hb, hemoglobin; MCV, mean cor-puscular volume; MCH, mean cor-puscular hemoglobin; RDW, red cell distribution width.

Due to persistent hypochromic microcytic anemia requiring blood transfusion and poor response to oral iron supplement despite of full dose and compliance a trail of parenteral iron (Ferric carboxymaltose 20 mg/kg/dose, weekly, for 4 doses) was initiated with significant improvement in hemoglobin and MCV and drop in RDW as showed in the Fig. 3. Her serial CBC and iron profile results have been summarized in the Fig. 3 and 4.

Figure 4. Summary of serial iron pro-file. TIBC, total iron binding capa-city.

Our case describes an undiscovered concordance of Nabais Sa-de Vries syndrome and beta thalassemia with refractory microcytic hypochromic anemia as our patient has concurrent SPOP and HBB genetic mutation and clinical features of NSDVS1 and thalassemia along with resistant iron deficiency anemia.

Nabais Sa-de Vries syndrome (NSDVS) is a neurodevelopmental disorder first time described in 2020 [1]. The de novo missense mutations in speckle-type pox virus and zinc finger protein (SPOP) on chromosome 17q21 [2,3,12] caused this syndrome. Our patient presented at one year of age with microcephaly, micrognathia, low-set ear, and hypotonia which is suggestive of NSDVS1. Recur-rent somatic variants in SPOP are cancer-specific; endometrial and prostate cancers result from gain-of-function and dominant negative effects toward BET proteins, respectively. Nabais et al. in 2020, reported six de novo pathogenic missense variants in SPOP in seven individ-uals with developmental delay and/or intellectual disability, facial dysmorphisms, and congenital anomalies [1]. Five individuals shared craniofacial dysmorphisms, including (relative) macrocephaly and hypertelorism, that were strikingly different from those of the other two individuals who had congenital microcephaly.

The literature review does not report any specific hem-atological association including hemoglobinopathy and refractory iron deficiency anemia in NSDVS1. However, our patient presented with microcytic hypochromic anemia, unresponsive to oral iron supplements while showed significant improvement in hemoglobin level with parenteral iron therapy. Her gastroenterology assessment was also negative for any identifiable cause of her oral iron supplement refractoriness. Her genetic study detected the presence of mutations in the hemoglobin genes including both the α-globin and β-globin genes.

In summary, this report describes an undiscovered concordance of Nabais Sa-de Vries syndrome and thalassemia as our patient has concurrent SPOP and HBB genetic mutation and clinical features of NSDVS1 and thalassemia along with iron refractory iron deficiency anemia. To the best of current knowledge, no previous case study has reported the concurrence of microcytic hypochromic anemia or hemoglobin gene mutations in NSDVS1 patients, thus this finding is the first time reported here. Further studies on the genetic association are needed, as more cases are reported we may better understand the mechanisms of the associated hematological manifestations and disease course involved.

The authors have no conflict of interest to declare.