Thiamine-responsive megaloblastic anemia: identification of novel compound heterozygotes and mutation update.

Objective: To determine causative mutations and clinical status of 7 previously unreported kindreds with TRMA syndrome, (thiamine-responsive megaloblastic anemia, online Mendelian inheritance in man, no. 249270), a recessive disorder of thiamine transporter Slc19A2.

Study Design: Genomic DNA was purified from blood, and SLC19A2 mutations were characterized by sequencing polymerase chain reaction-amplified coding regions and intron-exon boundaries of all probands.

Human erythrocyte membrane band 3 protein influences hemoglobin cooperativity. Possible effect on oxygen transport.

Hemoglobin function can be modulated by the red cell membrane but some mechanistic details are incomplete. For example, the 43-kDa chymotryptic fragment of the cytoplasmic portion of red cell membrane Band 3 protein and its corresponding N-terminal 11-residue synthetic peptide lower the oxygen affinity of hemoglobin but effects on cooperativity are unclear. Using highly purified preparations, we also find a lowered Hill coefficient (n values <2) at subequivalent ratios of Band 3 fragment or of synthetic peptide to Hb, resulting in an oxygen affinity that is moderately decreased and a partially hyperbolic shape for the O2 binding curve.