[Amino acids and trisomy 21].

The relative concentrations of plasmatic and urinary amino acids were analysed in 79 trisomic-21 patients, 322 mentally retarded non-trisomic patients, and 206 controls. No true amino acidopathy was found in 21-trisomy, but in plasma a deficit of serine and an excess of cysteine and lysine are highly significant. Excesses of cysteine, methionine, tyrosine, and methyl-histidine are also typical in urine.

[Familial testicular regression syndrome].

The rare syndrome of embryonic testicular regression or agonadism with XY karyotype is described in this paper in a sibship of 7 including 3 cases of regression at a earlier time (in three amenorrheic sisters and on case of tardive and incomplete regression in a brother with bilateral testicular hypotrophy. The antigen H-Y is present in the three sisters. The pathogenesis of this syndrome, compared with that of pure gonadal dysgenesis is discussed.

[Reciprocal syndromes caused by deficiency duplication resulting from maternal t(10;18)(p12;q22) translocation].

The detection of a familial translocation, t(10;18)(p12;q22), has made possible the observation in type and countertype of two related persons with opposite chromosomal imbalance: trisomy 18q22----18qter with monosomy 10p12----10pter in one of the two and monosomy 18q22----10pter in the other. In each case the abnormalities attributable to monosomy overrule those attributable to monosomy overrule those attributable to the associated trisomy.

Genetic diseases in Lebanon.

Lebanon has a high incidence of common and rare genetic diseases, due probably to the mosaic different ethnic origins and the high rate of consanguineous marriages in certain communities. Two major investigations, exploring the genetic structure of the Lebanese population, indicated the population to be caucasiods (though Oriental traits were found). These investigations involved studies of dermatoglyphics, and type and distribution of genetic markers and protein variants.