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Titus H. J. Huisman investigated hemoglobin variation and the different globin chains composing it. His university laboratory's history identifies him as a leader of hemoglobin research at the Medical College of Georgia.^[ref]

Titus H. J. Huisman coauthored the 1968 chemical study distinguishing glycine and alanine at position 136 in gamma-globin material. That observation supported the presence of multiple sequence forms within human fetal hemoglobin.^[ref] It was evidence from protein chemistry, rather than direct sequencing of the modern HBG1 and HBG2 genes.

In a 1970 report with W. A. Schroeder and colleagues, Titus H. J. Huisman followed G-gamma globin and A-gamma globin proportions in seven infants after birth. The reported G-gamma-to-A-gamma ratio changed from approximately 3:1 at birth toward 2:3 by five months.^[ref] This study connects molecular discrimination with a time-dependent biological observation, rather than treating all gamma chains as one unchanging category.

An original accounting example shows why a ratio is not an absolute production rate. A 3:1 ratio corresponds to G-gamma and A-gamma fractions $3/4$ and $1/4$; a 2:3 ratio corresponds to $2/5$ and $3/5$. If a stipulated total pool falls from 100 to 20 units, the A-gamma amount falls from 25 to 12 even though its fraction rises from 0.25 to 0.60. These totals are invented for the calculation, not measured values from the paper.

The scientific distinction is useful whenever developmental changes are described by a normalized molecular signal. Sequence identity, relative abundance, absolute amount and assembly pairing remain different questions. Gamma-chain pairing bounds from bulk composition further shows why chain fractions alone do not identify every fetal hemoglobin assembly.

W. A. Schroeder, also identified as Walter A. Schroeder in a primary publication, investigated hemoglobin structure and the chemical differences among its globin chains. A contemporary Caltech account describes his work on fetal hemoglobin sequences and its distinction from adult hemoglobin.^[ref]

The 1968 study on which W. A. Schroeder is first author reported glycine and alanine at position 136 in human fetal gamma-chain material. This supplied chemical evidence that the label gamma-globin encompassed distinguishable sequence forms, motivating the inference of multiple structural genes.^[ref] The historical observation concerned protein chemistry; it was not direct sequencing of the modern HBG1 and HBG2 loci.

A 1970 report with Titus H. J. Huisman followed the changing proportions of G-gamma globin and A-gamma globin after birth. Its primary author information explicitly spells Walter A. Schroeder and gives the Caltech affiliation.^[ref] That documented connection supports the expanded-name alias while preserving the original initial-based identifier.

An original analytical example explains why chemical discrimination and quantitative abundance are separate achievements. Suppose sequence-selective signals are $I_G=60$ and $I_A=40$, with responses per unit amount $k_G=1$ and $k_A=2$. The corresponding amounts are 60 and 20, so the G-gamma chain fraction is $60/(60+20)=0.75$, rather than the raw signal fraction 0.60. These stipulated numbers illustrate response correction; they are not measurements reported by Schroeder.

Even correctly measured chain proportions leave another question open: which forms share the same fetal hemoglobin assembly? Gamma-chain pairing bounds from bulk composition shows why that requires additional molecular information. Distinguishing sequence, abundance and assembly makes the scientific contribution of the chemical studies more precise.

A labeled portrait appears on page 31 of Caltech's 1986 retirement notice.