64 



BIOLOGIC BASIS OF SEX 



disjunction in oogenesis as the most im- 

 portant cause of this condition. Some women 

 who have had previous JMongoloid progeny 

 have an increased risk of having others. 

 This is an important consideration in that 

 genetic factors may materially assist in 

 bringing about nondisjunction in man as 

 they are known to do in Drosophila (Gowen 

 and Gowen, 1922; Gowen, 1928). The prod- 

 ucts of the nondisjunctions approach those 

 expected on random distribution of the 

 chromosomes (Gowen, 1933) so that occa- 

 sionally more than one type of chromosome 

 disjunction will appear in a given indi- 

 vidual. Such a case is that illustrated by 

 Ford, Jones, Miller, Mittwoch, Penrose, 

 R idler and Shapiro (1959) in which the 

 nondisjunctional type included not only 

 that for the chromosome important to Mon- 

 golism but also the sex chromosomes sig- 

 nificant in determining the Klinefelter 

 condition. This individual showed 48 chro- 

 mosomes, 22 pairs of normal autosomes, 3 

 sex chromosomes XXY, and a small acro- 

 centric chromosome matching a pair of 

 chromosomes, the 21st, within the smallest 

 chromosomes of the human idiogram. The 

 analysis of Mongolism showed the way for 

 the separation of the various human sex 

 types through chromosome analyses. 



Chromosome translocations furnish an- 

 other means of establishing an anomaly 

 that may then continue on an hereditary 

 basis as either the male or female may 

 transmit the rearranged chromosomes. Po- 

 lani, Briggs, Ford, Clarke and Berg (1960), 

 Fraccaro, Kaijser and Lindsten (1960b), 

 Penrose, Ellis and Delhanty (1960) and 

 Carter, Hamerton, Polani, Gunalp and 

 Weller (1960) have studied Mongoloid 

 cases which they interpreted in this manner. 

 In some cases the rearranged chromosomes 

 have been transmitted for three generations. 

 Several of the translocations were con- 

 sidered to include chromosomes 15 and 21. 



Another trisomic autosomal type was rc- 

 ])ortcd by Patau, Smith, Therman, Inhorn 

 and Wagner (1960). The patient was fe- 

 male and had 47 chromosomes. The extra 

 chromosome was a medium-sized acrocen- 

 tric autosome belonging to the D group. 

 Despite extensive malformations affecting 

 several organs the patient lived more than 

 a year. Another female iiortraying the same 



syndrome has since been found, so other 

 cases may be expected. Among the charac- 

 teristics are mental retardation, minor mo- 

 tor seizures, deafness, apparent micro or 

 anophthalmia, horizontal palmar creases, 

 trigger thumbs, Polydactyly, cleft i)alate, 

 and hemangiomata. 



The third trisomic type was also reported 

 by Patau, Smith, Therman, Inhorn and 

 Wagner (1960). Six individuals have been 

 observed. The characters affected are men- 

 tal retardation, hypertonicity (5 patients), 

 small mandible, malformed ears, flexion of 

 fingers, index finger overlaps third, big toe 

 dorsiflexed (at least 4), hernia and/or dia- 

 phragm eventration, heart anomaly (at 

 least 4), and renal anomaly (3). The sexes 

 were two males and four females. The ex- 

 tra chromosome was in the E group and was 

 diagnosed as number 18. Edwards, Harnden, 

 Cameron, Crosse and Wolff (1960) have 

 described a similar case but they consider 

 the trisomic to be number 17. Ultimate com- 

 parisons of these types no doubt will decide 

 if this is a 4th trisomic or if all the cases 

 belong in the same group. 



The Sturge-Weber syndrome apparently 

 is caused by another trisomic. Locomotor 

 and mental abilities are retarded. Hayward 

 and Bower (1960) interpret the 3 chromo- 

 somes responsible as the smallest autosomes, 

 number 22, of the human group. 



Trisomic frequencies should be matched 

 by equal numbers of monosomies. Turpin, 

 Lejeune, Lafourcade and Gautier (1959) 

 have reported polydysspondylism in a child 

 with low intelligence, dwarfing, and multi- 

 l)le malformations of spine and sella turcica. 

 The somatic cell chromosome count was 

 only 45 but one of the smallest acrocentric 

 chromosomes appeared to have been trans- 

 located, the greatest part of this chromo- 

 some being observed on the short arm of one 

 of the 3 longer acrocentric chromosomes. 

 Th(> condition appears to be unique and not 

 likely to be found in other unrelated fami- 

 Vws. However, the phenotyj^ic effects were 

 so severe that all members of the proband's 

 family would seemingly be worthy of care- 

 ful sur\'('y for their chromosome character- 

 istics. 



The comi)lex pattern of multiple anom- 

 alies renders each syndrome distinct from 

 the otliei's. Chromosome losses or gains from 



