ABSTRACT
We report here 2 patients with chronic nonspherocytic hemolytic anemia (CNSHA) and severe red blood cell (RBC) adenylate kinase (AK) deficiency. One of these patients, a boy of Spanish origin, exhibited a neonatal icterus and splenomegaly and required blood transfusions until the age of 2 years. The other patient was a white, American infant born to parents who were first cousins; he also presented with neonatal icterus and anemia. In neither case was psychomotor impairment observed. The first patient was found to be a compound heterozygote for 2 different missense mutations, 118G>A(Gly40Arg) and 190G>A(Gly64Arg) (cDNA sequence first described by Matsuura et al, 1989). The second patient was homozygous for an in-frame deletion (GAC) from nucleotide (nt) 498 to 500 or nt 501 to 503 of the cDNA sequence, predicting deletion of either aspartic acid (Asp) 140 or 141. The crystal structure of porcine cytosolic AK was used as a molecular model to investigate how these mutations may affect enzyme structure and function.
Subject(s)
Adenylate Kinase/deficiency , Anemia, Hemolytic, Congenital Nonspherocytic/genetics , Erythrocytes/enzymology , Mutation , Child, Preschool , Humans , Infant , Male , Models, Molecular , Mutation, Missense , Sequence Deletion , Structure-Activity RelationshipABSTRACT
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Subject(s)
Child, Preschool , Male , Humans , Down Syndrome/complications , Pneumonia/complications , Anemia/complications , Hemothorax/complications , Recurrence , Hemosiderosis/complicationsABSTRACT
The large number of Alu repeats in the human genome provides abundant opportunities for unequal homologous recombination events that are responsible of several human diseases. We here describe a novel large FVIII gene deletion from a severe hemophilia A patient in which Alu-repetitive elements are directly involved in the origin of the mutation. Using a long-fragment PCR method, a approximately 23 kb deletion was delimited between introns 24 and 25. The resulting FVIII gene had a hybrid 2317-bp intron and lacked exon 25. Absence of exon 25 was confirmed at the RNA level. Multiple sequence alignment of this hybrid intron and normal introns 24 and 25 provided evidence of an homologous recombination event between two Alu repeats and the exact breakpoints were delimited to a 16 bp region. To our knowledge, this is the first report of hemophilia caused by unequal homologous Alu/Alu recombination. This mechanism, commonly related to genetic human disorders, may be involved in a significant number of hemophilia cases considering that FVIII is coded by an Alu-rich gene.
