Pediatr Blood Cancer 2014;61:1463–1465
BRIEF REPORT Dyserythropoiesis in a Child With Pyruvate Kinase Deficiency and Coexistent Unilateral Multicystic Dysplastic Kidney Marwa Abu El Haija,
1 MD,
You-Wen Qian,
Pyruvate kinase (PK) deficiency is the commonest enzyme deficiency in the glycolytic pathway leading to hemolytic anemia secondary to decreased Adenosine Triphosphate (ATP) synthesis in the red cells. synthesis. PK deficiency due to mutations in the PKLR (1q21) gene leads to highly variable clinical presentation ranging from severe fetal anemia to well compensated anemia in adults. We describe dyserythropoiesis in the bone marrow of a child with
Key words:
2
and Akila Muthukumar,
MD
1
*
transfusion dependent anemia and unilateral multicystic dysplastic kidney (MCDK) mimicking Congenital Dyserythropoietic Anemia type I (CDA type I). Persistently low erythrocyte PK levels and double heterozygous mutations present in the PKLR gene confirmed the diagnosis of PK deficiency. Pediatr Blood Cancer 2014;61:1463– 1465. # 2014 Wiley Periodicals, Inc.
dyserythropoiesis; hemolytic anemia; multicystic dysplastic kidney; pyruvate kinase deficiency
INTRODUCTION Pyruvate kinase (PK) deficiency is the commonest enzyme abnormality in the glycolytic pathway [1] which leads to hereditary hemolytic anemia secondary to decreased ATP synthesis. PK deficiency in red blood cells occurs due to mutation in the PKLR 1q21 [2] gene and leads to highly variable clinical presentation ranging from severe fetal anemia leading to hydrops fetalis [3,4] to well compensated hemolytic anemia in adults. We describe here the evidence of dyserythropoiesis in the bone marrow of a 3-month-old child who has PK deficiency and coexistent Unilateral Multicystic Dysplastic Kidney (MCDK). Dyserythropoiesis raised concerns of Congenital Dyserythropoietic Anemia type I (CDA type I) but persistently low erythrocyte PK levels and PKLR gene sequencing results consistent with double heterozygous mutations in the PKLR gene confirmed the diagnosis of PK deficiency.
CASE REPORT The patient was born full term as the first child to an 18-year-old primigravida mother. Ancestry of mother is mixed Hispanic and European while father is Hispanic with no history of consanguinity among parents. Mother had anemia during her third trimester of pregnancy which was thought to be secondary to iron deficiency and she required packed red blood cell (pRBC) transfusion once in the immediate postpartum period. The patient was diagnosed during intra-uterine period with left sided multicystic kidney, oligohydramnios, and mild pericardial effusion by prenatal ultrasonogram. At birth the patient was pale, required basic stimulation, and resuscitation as well as administration of oxygen. His Apgar scores were 6 and 9 at 1 and 5 minutes, respectively. He was treated in the neonatal intensive care unit due to further oxygen requirement. On physical examination, no abnormal facial features, skeletal abnormalities, or hepatosplenomegaly were noted except for 2/6 soft systolic heart murmur and a palpable left kidney on examination of abdomen. His complete blood count at birth revealed very low hemoglobin of 7.8 gm/dl and a high reticulocyte count of 36.8%. He received pRBC transfusion immediately after birth. Echocardiogram done after birth revealed ostium secundum Atrial Septal Defect (ASD). Renal Ultrasonogram done postnatally showed a small cystic structure measuring 7.2 cm 3 cm 3.6 cm in
C
MD,
2014 Wiley Periodicals, Inc. DOI 10.1002/pbc.24953 Published online 30 January 2014 in Wiley Online Library (wileyonlinelibrary.com).
diameter in the left renal fossa with no identifiable solid parenchyma consistent with left sided Muticystic Dysplastic Kidney (MCDK). Mild pelviectasis of right kidney was also seen. MRI abdomen confirmed the diagnosis of MCDK and ruled out any hemorrhage. The patient had transient thrombocytopenia with platelets ranging from 60,000 to 80,000/ml in the first week of life which improved spontaneously. Peripheral smear at birth showed macrocytic red cells with a moderate increase in poikilocytes, including schistocytes, and spherocytes. Increased polychromasia and nucleated red cells were suggestive of a hemolytic process either immune mediated or secondary to intrinsic red cell defects. His renal function tests were in the normal range. Fetomaternal bleeding was ruled out by maternal blood testing for fetal hemoglobin. There was no ABO or Rh incompatibility present to suggest immune hemolysis and Direct Antibody testing of the patient was negative. Infections like Parvovirus B19, Cytomegalovirus, and syphilis were ruled out by clinical evaluations and lab tests. Serum folate, ferritin, vitamin B12, and Glucose-6-phosphate Dehydrogenase enzyme levels were within normal limits. His blood tests revealed a low erythrocyte PK enzyme activity of 5.1 U/gHb (normal range 9.0–22.0 U/gHb). His peripheral smear showed a few spiculated red cells but no spheroechinocytes seen. At week 7 of age, his hemoglobin and reticulocyte count were 5.6 gm/dl and 2.58%, respectively. He underwent bone marrow aspiration at 3 months of age since his reticulocyte response was thought to be inadequate. Bone marrow showed increased erythropoiesis with cytoplasmic bridging between many erythroblasts and infrequent dyserythropoiesis which raised the concern of CDA type I (Fig. 1). 1
Department of Pediatric Hematology and Oncology, University of Texas Medical Branch at Galveston, Galveston, Texas; 2Department of Pathology, University of Texas Medical Branch at Galveston, Galveston, Texas Conflict of interest: Nothing to declare. Correspondence to: Akila Muthukumar, Assistant Professor of Pediatrics, Division of Pediatric Hematology/Oncology, University of Texas Medical Branch at Galveston, 301 University Blvd, TX 775550371. E-mail:
[email protected] Received 27 September 2013; Accepted 30 December 2013
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Haija et al. described earlier [5]. A previously unreported heterozygous variant in exon 3 of the gene (c.341T>C p.Ile114Thr) was also found. The patient received a total of three pRBC transfusions for low hemoglobin during first month of life and every 3–4 weeks in the first few months of life. At present he is clinically doing well with normal growth and development and continues to be pRBC transfusion dependent at 1 year of age.
DISCUSSION
Fig. 1. Bone marrow aspirate slide shows inter-cytoplasmic bridging (Wright–Giemsa staining, 500).
By electron microscopy, some nucleated red cell precursors in the bone marrow aspirate showing nuclear chromatin changes that mimic “Swiss Cheese” morphology as described in CDA type I were seen (Fig. 2). Cytogenomic microarray analysis showed no significant DNA copy number changes. PK levels were repeated twice prior to subsequent pRBC transfusions and they were 4.7 and 4.8 U/gHb done at ARUP Laboratories (Salt Lake City, UT). Since there was presence of dyserythropoiesis, sequencing of PKLR gene at 1q21 [2] which codes for PK in red cells was sent to confirm the diagnosis of PK deficiency. PKLR gene testing done at Centogene, Germany was positive with two heterozygous mutations c.1378G>A p.Val460Met, and c.341T>C p.Ile114Thr. One of the mutations has been
Since PK deficiency is usually associated with reticulocytosis, the disproportionately low reticulocyte count seen in the patient described above raised concerns about other causes of neonatal anemia. But, low reticulocyte count seen here could be explained by sequestration and destruction of the reticulocytes by the reticuloendothelial system in PK deficiency [6]. PK levels seen here were higher than a typical patient with homozygous mutation and could be explained by previous pRBC transfusions, presence of compound heterozygous mutation and higher values usually seen in children than in adults. Dyserythropoiesis seen in the bone marrow was initially thought to be secondary to CDA type I. Incomplete division of the nuclei leading to nuclear bridging as a characteristic feature of CDA type I has been described in studies of DNA content of erythroblasts [7]. Since PK deficiency is confirmed by the compound heterozygous mutation of the PKLR gene (1q21) as evidenced by gene sequencing, we think that dyserythropoieisis is likely secondary to ineffective erythropoiesis which has been described earlier. Evidence of extramedullary erythropoieis and ineffective erythropoiesis has been demonstrated in the spleen of a child with PK deficiency [8] and also in mutant mice with PK deficiency [9]. Higher levels of iron seen in patients with PK deficiency could be secondary to ineffective erythropoiesis in addition to other factors such as hemolysis [10]. MCDK is one of the commonest abnormalities detected by antenatal ultrasound and has been found to be associated with other urogenital abnormalities [11,12] and nonurogenital findings. Longterm follow-up studies show that majority of multicystic kidneys involute during first decade of life [13]. Interestingly, the MUC1 gene involved in Medullary Cystic Kidney Disease type I, which usually manifests in adults, is also located in the chromosome 1q21. Multicystic kidney is known to be associated with Diamond Blackfan Anemia, but its association with PK deficiency is not reported earlier. Since the gene coding for M2-PK, the isoenzyme of PK specific for kidneys is located in a different chromosome at 15q22 [14], we think that PK deficiency and MCDK are coexistent in this patient. Acquired erythrocyte PK deficiency has been reported earlier in some conditions with dyserythropoiesis [15,16]. This case report of dyserythropoiesis in a child with congenital PK deficiency supports earlier theories that ineffective erythropoiesis also contributes to anemia in PK deficiency along with ATP depletion.
ACKNOWLEDGMENTS Fig. 2. Electron microscopy examination of the bone marrow aspirate shows the red blood cell nuclear chromatin changes that mimic “Swiss Cheese” morphology as described in congenital dyserythropoietic anemia (25,000). Pediatr Blood Cancer DOI 10.1002/pbc
The authors thank Ketan N. Patel, MD, Department of Pediatrics, Division of Nephrology, UTMB Galveston for his helpful comments and assistance in preparation of the case report.
Dyserythropoiesis in Pyruvate kinase deficiency
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