New mutation in erythroid-specific delta-aminolevulinate synthase as the cause of X-linked sideroblastic anemia responsive to pyridoxine.
OBJECTIVE
Congenital sideroblastic anemias (SA) are characterized by the presence of ringed sideroblasts in the bone marrow. The most common form is X-linked SA, which results from mutations in erythroid-specific δ-aminolevulinate synthase (ALAS2), the first enzyme in heme biosynthesis. In addition, autosomal recessive mutations in the erythroid-specific mitochondrial transporter SLC25A38 and glutaredoxin 5 (GLRX5) have recently been identified in SA patients with isolated erythroid phenotype.


METHODS
We studied 5 young males with congenital SA from the Czech Republic. Mutation analysis was performed on the complete coding regions of 3 candidate genes (ALAS2, SLC25A38 and GLRX5), and the enzyme activity of ALAS2 was measured by a continuous spectrophotometric assay.


RESULTS
We found the previously published R452H and R452C ALAS2 mutations in 3 patients. A novel K156E substitution in ALAS2 was discovered in 1 pyridoxine-responsive patient. The functional study showed that this substitution severely decreases ALAS2 enzyme activity. In 1 pyridoxine-refractory patient, no mutations were detected in ALAS2, SLC25A38 or GLRX5.


CONCLUSIONS
Our report extends the list of known ALAS2 mutations, with the addition of a novel K156E substitution that is responsive to pyridoxine treatment and contributes to the general knowledge of congenital SA cases characterized worldwide.
Department of Biology, Faculty of Medicine, Palacky University, Olomouc, Czech Republic.
Jana
J
Kucerova
Monika
M
Horvathova
Renata
R
Mojzikova
Petra
P
Belohlavkova
Jaroslav
J
Cermak
Vladimir
V
Divoky
D000624:5-Aminolevulinate Synthetase / Q000235:genetics* / Q000378:metabolism; D000328:Adult; D000756:Anemia, Sideroblastic / Q000188:drug therapy / Q000201:enzymology / Q000235:genetics; D001483:Base Sequence; D040181:Genetic Diseases, X-Linked; D006801:Humans; D008297:Male; D009154:Mutation; D011736:Pyridoxine / Q000627:therapeutic use; D016415:Sequence Alignment
D000624:5-Aminolevulinate Synthetase; C480079:ALAS2 protein, human; D011736:Pyridoxine