[A cytogenetic study of the functions of the variable regions in human C heterochromatin. III. The relationship between the amount of C heterochromatin and the occurrence of the fetal alcohol syndrome].

It has been shown elsewhere that in children with growth retardation and gene syndromes (Russell-Silver, Dubowitz etc.), and in healthy children with inherited short stature the total amount of C heterochromatin in chromosomes 1, 9, and 16 was reduced as compared to the control. A correlation between the C heterochromatin reduction and the intrauterine growth retardation was suggested. A study of C heterochromatin in patients with fetal alcohol syndrome has shown that the chromosome sets of all the 11 children examined are identical to those of the above-mentioned patients. This fact may indicate that a small amount of C heterochromatin may play the leading role in realization of the alcohol effect, since this C heterochromatin deficiency makes the early embryogenesis open to injury to external effects. A possible functional role of C heterochromatin in disturbances of the developmental homeostasis are discussed. These disturbances concern the growth retardation and the lack of resistance to the effect of external and internal factors.