The chromosomes of man

Jérôme LEJEUNE, Marthe GAUTIER et Raymond TURPIN.

Letters to the editor, 25 April 1959.


SIR,- We note in your leading article of April 4 a genuine misunderstanding of a simple French word. Referring to our paper (1), you say that " it is fairly certain that this extra chromosome is the result of tripling of one of the normal pairs, and not, as Lejeune et al. call it, a supernumerary in the true sense of something quite extraneous to the normal complement " (our italics).

We had in fact described a " chromosome supplémentaire " in mongolian cells. The French words " supplémentaire " and " sumuméraire " (the latter used in our second paper (2)) do not mean " something quite extran-eous to the normal complement", but merely " supplementary " or " supernumerary ". Examination of our second note to the Academic des Sciences on March 16, reporting nine cases of mongolism with a " supplementary " or " supernumerary " chromosome, would have avoided such a misunderstanding. In this note we raise the hypothesis of the non-disjunction of a small telocentric pair as an explanation of the " supernumerary " chromosome.

The linguistic troubles are more surprising since Ford et al. (3) and Jacobs et al. (4) felt there was no ambiguity attached to the term, which they translate by extra, additional, or supernumerary.

Finally it is entirely true that we have "for reasons so far unspecified, also thought it worth investigating mongolism ". It passes our imagination that a supposedly well-authorised critic should naïvely wonder about the reasons leading to scientific achievements.

We should be grateful if we could extend through your columns our appreciation to Dr. Ford and to Dr. Court Brown for their kindness in informing us, before publication, of their beautiful work which confirms our discovery.



1. Lejeune, J., Gautier, M., Turpin, R. C.R. Acad. Sci., Paris, Jan. 26, 1959, 248, 602.

2. Lejeune, J., Gautier, M., Turpin, R. ibid. March 16, 1959, p. 1721.

3. Ford, C. E., Jones, K. W., Miller, O. J., Mittwoch, U., Penrose, L. S., Ridler, M., Shapiro, A. Lancet, April 4, 1950, p. 709.

4. Jacobs, P. A., Baikie, A. G., Court Brown, W. M., Strong, J. A. ibid. p. 710.

5. White, M. J. D. Animal Cytology and Evolution; p. 156 et seq. Cambridge, 1954.


The term " supernumerary chromosome " is used loosely by some to mean any kind of additional chromo-some, but increasingly in the restricted sense (5) in which we employed it. Of the papers in our issue of April 4, one (4) uses it in the restricted sense, one (3) uses it more loosely. We were clearly wrong in translating Dr. Lejeune and his colleagues (5) term as " supernumerary ", and in assuming that they might be using the word in the restricted sense we went further astray. Their second paper, (2) which was not available to us three weeks ago, makes this quite clear, and indicates that they are in substantial agreement with the British workers as to the probable nature of the 47th chromosome.

We can assure our French colleagues that no criticism lay behind our inquisitiveness about the reasons which