C-banding and AgNOR-staining were still effective complementary methods to indentify chromosomal heteromorphisms and some structural abnormalities in prenatal diagnosis

Table 2 Number and frequency of autosomal heteromorphisms in different groups

Group	Chromosome heteromorphisms
Group	No. of cases	1/9/16/19qh±	D/G variation	inv(9)	Total of heteromorphisms (n; %)	Chi-square test
Group A^a	131	4 (3.05%)	4 (3.05%)	2 (1.53%)	10 (7.63%)	Pearson χ²=0.783 p>0.05
Group B^b	2839	73 (2.57%)	65 (2.29%)	26 (0.92%)	164 (5.78%)
Total	2970	77 (2.59%)	69 (2.32%)	28 (0.94%)	174 (5.86%)

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