Babu A, Verma R S
Am J Hum Genet. 1986 Apr;38(4):549-54.
The staining property of pericentromeric heterochromatin of chromosome 18 is compared by C-banding and restriction endonuclease AluI digestion methods. Only a small distal fraction of C-band of chromosome 18 is observed to be resistant to AluI treatment, which positively stained with subsequent Giemsa staining. The resistant fraction is characteristic and usually located toward the short arm. The extensive heterogeneity of constitutive heterochromatin revealed by AluI treatment is useful in demonstrating the heterozygosity of homologous chromosomes. This, in turn, may provide frequent markers to identify the chromosomes 18's. This present approach can be utilized in evaluation of the families to describe the origin of the extra chromosome 18 in Edward syndrome. As an example, one such family has been investigated where the additional chromosome 18 originated due to paternal nondisjunction at meiosis I.
采用C带和限制性内切酶AluI消化方法比较了18号染色体着丝粒周围异染色质的染色特性。观察到18号染色体C带只有一小部分远端对AluI处理有抗性，随后吉姆萨染色呈阳性。抗性部分具有特征性，通常位于短臂。AluI处理揭示的组成型异染色质的广泛异质性有助于证明同源染色体的杂合性。反过来，这可能提供频繁的标记来识别18号染色体。目前的这种方法可用于评估家庭，以描述爱德华综合征中额外18号染色体的起源。例如，已经对一个这样的家庭进行了调查，其中额外的18号染色体是由于减数分裂I期父源不分离而产生的。
