Spinal muscular atrophy in Venezuela: quantitative analysis of SMN1 and SMN2 genes

Egyptian Journal of Medical Human Genetics

Table 1 Number of copies of SMN1 and SMN2 genes in the Venezuelan population sample

Gene	Estimated number of copies	Ranges of values of 2^−ΔΔCT	SD	Number of individuals (n = 49)	Frequency (%)
SMN1	1	0.35	-	1	2.0
	1 or 2 (*)	0.66–0.72	-	6	12.2
	2	0.83–1.10	0.14	37	75.5
	3	1.36–1.38	0.01	2	4.1
	4 or 5	2.42–2.88	0.23	2	4.1
	6 or 7	3.30	-	1	2.0
SMN2	0	0	-	8	16.3
	1	0.26–0.53	0.13	27	55.1
	1 or 2 (*)	0.67–0.74	-	2	4.1
	2	0.82–1.20	0.19	7	14.3
	3	1.35–1.70	0.18	5	10.2

The relative gene copy numbers were estimated by the 2^−ΔΔCT expression (Livak’s method) [8]; for two gene copies, its value is expected to be around 1; in deletion carriers (one gene copy), it is about 0.5, and in homozygous deletion individuals, it is 0
SD standard deviation
*Uncertain values for classification of gene copy numbers