Short answer: In many nutrigenomic reports the COMT V158M was seen as 'slow' if +/+ and ‘fast” if -/-. In vitro/test tube results do show this result when you focus on only the one SNP rs4680. Researchers now know this isn’t an accurate portrayal of real-life where SNPs within the same gene interact with each other.
Long answer: What was reported in the previous StrateGene was the best representation based on available research at the time. Generally speaking, looking at individual SNPs is an incomplete picture compared to looking at SNPs in combination. Understanding the activity of combinations of SNPs is more challenging and requires more sophisticated research, but paints a more complete picture.
Now that StrateGene uses a custom-built genetic chip, we are able to report a researched 4 SNP COMT haplotype. The 23andme and Ancestry DNA raw data files the earlier StrateGene used did not contain all 4 SNPs required to construct the COMT activity haplotype. Thus, your previous (old) StrateGene reported on the best available data at the time.
Here are direct quotes from published research showing the superiority of this well researched and replicated COMT haplotype versus individual COMT SNPs:
“Secondly, synonymous SNPs within COMT haplotypes can have effects on protein function that exceed the effects of individual SNPs. Several recently published studies support the theory that the collective grouping of SNPs in haplotypes has a stronger association with the assessed phenotype than individual SNPs (18,25,27– 29). However, almost all previously published haplotype association studies demonstrate the importance of haplotype reconstruction because combinations of SNPs result in synergistic effects on protein function. Recently, Duan et al. (25) showed that synonymous SNPs within haplotypes can have functional consequences drastically different from those of each isolated mutation.” https://pubmed.ncbi.nlm.nih.gov/15537663/
“Four central SNPs (rs6269, rs4633, rs4818 and rs4680) in the COMT gene combine to form three common haplotypes (Diatchenko et al., 2005), and these are associated with varying levels of COMT enzyme activity (Nackley et al., 2006). The fact that the wild type Val158 (G) allele is present in both the high and low COMT activity haplotypes (Diatchenko et al., 2005) demonstrates the importance of studying haplotypes rather than single SNPs. ” https://pubmed.ncbi.nlm.nih.gov/21355050/
“…Consistent with our findings, several previous studies have revealed a more significant biological effect of COMT haplotypes than single SNPs. For examples, COMT haplotypes rather than any single SNPs are associated with the activation of the PFC (Meyer-Lindenberg et al. 2006), show significant association with the risk of schizophrenia (Nicodemus et al. 2007), and exhibit a significant modulation on the intelligence-related white matter integrity (Liu et al. 2010).” https://pubmed.ncbi.nlm.nih.gov/31332515/