FREE AMINO ACIDS OF BLOOD AND URINE 249 
cluded that this frequency of excreters could be taken as a hereditary character of 
the white, being monogenic and recessive*!; °3, According to GARTLER ef al.** BAIBA 
output in those excreters could amount up to 70 mg/day. These data have been ob- 
tained by means of paper chromatography techniques. By similar methods, LinpAn’”? 
in Gambia, assigned a frequency of some 25°% of BAIBA excreters as a genetic charac- 
ter, here too hereditary and recessive, to the colored population (Central African tri- 
bes) living in the area where he performed his study. In other population groups, na- 
mely among Asians, the percentage of BAIBA excreters is said to be still higher”®. 
Excretion was said to be independant of age, sex and diet, but was considered to be 
under the control of more than one gene. The distribution curve is bimodal; among 
Mongoloid subjects 60% are claimed to be BAIBA excreters whereas among the Ne- 
eroid type of individuals the frequency is of the order of 40% and this percentage 
drops to 10% among Caucasians*’. Originally it was considered to be a renal type of 
aminoaciduria®° but this has become doubtful; DENT"! includes it rather in his third 
category of aminoaciduria process, “no threshold” category, the threshold being 
very low if there is one. The point to be stressed here is twofold: first, the analytical 
method used in these studies is questionable from the quantitative point of view; 
and secondly, it seems that there could be an underlying factor, responsible for 
BAIBA excretion, that probably escaped the scrutiny of former investigators. 
From the quantitative point of view, it seems very hazardous to judge the amount 
of BAIBA excreted from semi-quantitative results furnished by paper chromatog- 
raphy techniques, especially when an amino acid excreted in minute amounts is 
concerned. Moreover, in many cases, the daily BAIBA output was estimated from 
6-h urine collections®’, a procedure which is to be considered as definitely unsafe. 
If the frequency of 10% of BAIBA excreters, indicated by Harris as a genetic 
character of the white population of the British Isles, was to be fully accepted, 
the odds would have been that at least two or more BAIBA excreters should 
show up in the group of 34 white normal subjects, 24 adults and ten children 
picked at random, whose aminoaciduria is described in the section FREE AMINO 
ACIDS IN URINE AND BLOOD PLASMA. None of them was abnormal in this res- 
pect. Of course, it is realized that this set of observations is of too small a s1ze 
to permit a conclusion. A similar observation has been made by Dr. H. Vis™, who 
extensively studied aminoaciduria in chronic protein deficiency among Central- 
African populations by means of ion-exchange chromatography. Vis found only 
two or three cases in a group of 45 subjects of various ages, whose BAIBA 
excretion could be considered as definitely abnormal, hence approx. 4-6%, a fre- 
quency much lower than the 25% assigned by LinDAN to such a population group. 
The previously unsuspected factor underlying here, as will be seen in the next section 
is that BAIBA may be considerably increased owing to chronic protein deficiency, 
a condition which is unfortunately not rare in underdeveloped countries. Impaired 
nutritional conditions probably have more bearing on the frequency of hyper- 
aminoaciduria than any genetic character. 
Free amino acid excretion in protein malnutrition 
Low protein content of the available diet of populations living in tropical under- 
developed areas leads primarily to a degeneration of certain organs, namely those 
References p. 261/262 
