Letters from L S Penrose (carbon copies to various) Letters from Penrose to the following people: Kemp, N H, 20 Dec 1961, regarding examination of chromosomes from the skin culture of an infant patient with congenital disorders; Editor, The Lancet, 28 Jun 1963, enclosing a letter for publication on discovery of an autosomal ring chromosome in an infant patient; Wigley, G S, 1 Jun 1964, enclosing tabulated data on percentages of Down's syndrome births by maternal age group; Berg, J M, 7 Sep 1964, requesting Berg's attendance at the Extraordinary Meeting of the Editorial Board of the Journal of Mental Deficiency Research, and detailing points for discussion; Kirman, B H, 7 Sep 1964, inviting Kirman to the Extraordinary Meeting of the Editorial Board of the Journal of Mental Deficiency Research, and detailing points for discussion; Lashoff, J, 1 Feb 1965, enclosing data on the distribution of Down's syndrome by maternal age from a sample of cases in Middlesex. 1961