Letters and Correspondence

Transient Vlll Concentrate

to Monoclonal Antibody-Purified Factor

To the Editor: We report two cases of transient inhibitor to monoclonal antibody-purified factor VIII concentrate similar to those previously reported to Monoclate (Armour) by Drs. Kessler and Sachse [I]. In our comprehensive hemophiliac clinic, we yearly evaluate factor levels and check for inhibitors. Most of our patients are on a home-infusion program. Two patients who had never had any inhibitors to factor VIII developed them while receiving Hemophil M (Baxter/Travenol). Patient MF, 32-year-old male with a random factor VIII level of < 1% received Hemophil M home shipment for self-treatment of spontaneous bleedings starting July 19, 1988. On November 21, 1988, he had a 4.5 Bethesda Units (BU) inhibitor detected, although he had no clinical problem controlling his bleeds. He was switched to Koate HT (Cutter), and the next annual testing showed absent inhibitor, which has remained so to date. A second patient, RL, age 49 years with random factor VIII level < 1% also received Hemophil M on July 11, 1988, for home treatment of spontaneous bleeds. On January 22, 1989, he had a 0.9 BU inhibitor. He was switched to Koate HT on June 15, 1989. On November 27, 1989, the BUS were 6.4. He was switched to Monoclate (Armour), and by January 8, 1990, his inhibitor level was absent, and it has remained so to present. Our experience shows that Hemophil M in two instances did produce a transient inhibitor that was not clinically significant. Monoclate was used without problem. We continue close surveillance of patients receiving new-generation factor VIII concentrate products and urge the same in other treatment centers

L‘ Department of lnternal Medicine, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, Tennessee

REFERENCES

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percentage of ring sideroblasts in our patients ranged between 15% and 85%. According to our recently published criteria [4], two patients had pure sideroblastic anemia (PSA), which is confined to dyserythropoiesis, and eight patients had refractory anemia with ring sideroblasts (RARS), which is characterized by additional dysplastic features of granulopoiesis and/or megakaryopoiesis. Total DNA from bone marrow cells was extracted by standard methods. Samples of -5 p g were digested with restriction endonucleases PvuII, BamHI, and SacI, respectively, separated by agarose (0.8%) gel electrophoresis, and transferred onto nylon filters. The filters were hybridized with a specific mtDNA probe kindly provided by Prof. G. Attardi (California Institute of Technology, Pasadena, CA). The probe consists of an MboI fragment of mtDNA (positions 1-739), cloned into the BamHl site of pUC-9. This probe hybridizes with a region containing the origin of replication of the heavy strand (OH).Deletion of 0, would render the mtDNA molecule incompetent of replication and thus prevent its propagation. Accordingly, to date all mtDNA deletions studied at the molecular level spare this origin of replication. Therefore, the mtDNA probe we employed can be expected to hybridize with any replicating mtDNA, regardless of the extent of possible deletions. Because deletions can be missed if they eliminate the restriction site of the enzyme used for linearizing mtDNA, we did not rely solely on restriction digestion with PvuII (introducing a single cut at nt2650) but always performed a second digestion with BamHI (cutting at nt14258). Another enzyme (SacI), which usually recognizes two widely spaced restriction sites (nt36 and nt9643). was employed for rough localization of deletions. Gel electrophoresis compared every digest with identically treated DNA obtained from a healthy control. Hybridized mtDNA was visualized with the Digoxigenin nonradioactive labelling and detection system (Boehringer, Mannheim, Germany). In none of our patients with AISA did electrophoretic mobility of linearized mtDNA suggest a major deletion or duplication. We always found a single band of 16.5 kb after BamHI and PvuII digestion, respectively, and two bands of 9.6 kb and 6.9 kb after treatment with SacI. Control experiments with deleted mtDNA from patients with mitochondrial myopathies [5] (kindly provided by Professor A. Harding and Dr. M. Sweeney, Institute of Neurology, Queen Square, London) showed that we were able to detect deleted mtDNA even if its amount was only -1% of the total mtDNA. Our findings do not exclude the possibility that mtDNA from patients with AISA contains small deletions or point mutations, which can be very important, as shown for several neurological diseases.

1. Kessler CM, Sachse K: Factor VIII: C inhibitor associated with monoclonal-

NORBERT GA~ERMANN HENRIKE Lon CARLO AUL WOLFGANG SCHNEIDER

antibody purified F Vlll concentrate. Lancet 335:1403, 1990.

Abteilung fiir Hamatologie, Onkologie und klinische lmmunologie, Medizinische Klinik und Poliklinik, Heinrich-Heine-Universitat, Dusseldorf, Germany

No Large Deletions of Mitochondrial DNA in Acquired Idiopathic Sideroblastic Anemia (AISA)

REFERENCES

To the Ediror: We read with interest the concise review by Nusbaum [ 11 on the genetic bases of sideroblastic anemia. We have also been speculating for some time that acquired idiopathic sideroblastic anemia (AISA) might be caused by mutations of the mitochondria1DNA (mtDNA). The report by Rotig et al. [2] on a deletion of mtDNA in Pearson’s mmow/pancreas syndrome, which is associated with sideroblastic anemia, prompted us to examine the mtDNA of bone marrow cells in patients with AISA. For Southern blotting of mtDNA, we obtained -5 ml of bone marrow from 10 patients with AISA who presented for regular control biopsies. The diagnosis of AISA met the criteria proposed by the French-AmericanBritish (FAB) Cooperative Group for the classification of MDS 131. The

I. Nusbaum NJ: Concise review: Genetic bases for sideroblastic anemia. Am J Hematol37:41, 1991 2. Rotig A , Colonna M, Bonnefont JP, Blanche S , Fischer A, Saudubray JM, Munnich A: Mitochondrial DNA deletion in Pearson’s marrowipancreas syndrome. Lancet i:902, 1989. 3. Bennett JM,Catovsky D, Daniel M-T, Flandrin G , Galton DAG, Gralnick HR, Sultan C , The French-American-British (FAB) Cooperative Group: Proposals for the classification of the myelodysplastic syndromes. Br J Haernatol 5 I : 189, 1982. 4. Gattermann N , Aul C, Schneider W: Two types of acquired idiopathic sideroblastic anaemia (AISA). Br J Haematol74:45, 1990. 5. Holt IJ, Harding AE, Morgan-Hughes JA: Deletions of mitochondria1 DNA in patients with mitochondrial myopathies. Nature 331:717, 1988.