Another Recombination Within the HL-A System

A New Case of Crossing‐Over in the HL‐A System

“…This observation of recombination in the HL-A system may be added to the 11 families with a recombinant observed by Svejgaard et al (1971) in 3 different Scandinavian countries ( 309 families) and to miscellaneous recombinant families puhlished by Bodmer et al (1970) : 2 reconibinants among 188 families and by Dausset et al (1970) The frequency of recombinations in the HL-A system is 0.0081 according to thc Scandinavian study (Svejgaard et al 1971 ) dealing with 1 1 cases among 1,362 parental meiotic divisions with a small but not significant excess of maternal recombinations (0.0099) compared to paternal recombinations (0.0061 ). The recombinant child we observed is the second in the sibship, which neither supports nor contradicts the observations of Svejgaard et al (1971) that recornhiriation seems to increase with the age of the parents (in 8 of 10 families, the recombinant child belonged to the last half of the sibship Klouda & Lawler ( 1972) and, curiously, the recombination was between (1,8) and (2,12), exactly as in our case except that it is observed in the paternal garnete instead of the maternal gamete. It cannot be said if this is a merc coincidence due to the fact that ( I $ ) is the less rare of the HL-A haplotypes (0.077) and HL-A2 the most frequent gene (0.26), or if on the two neighour cistrons, the HL-A genes 1 and 8, are somewhat further apart, increasing thr chance of recombination.…”

Another HL-A27 Recombinant

“…There have been a number of reports of otherwise normal families in which recombination within the HL-A system has occurred [I, [3][4][5][6][7][8][9][10][11][12][13][14] and in the largest series it was found in 11 of 1,362 meiotic divisions giving a frequency of 0.0081 [12].…”