magna labs

Magna Labs has cooperated with its sister organization Leyden Delta and the Cardiff University on a Molecular Psychiatry article on the importance of the Duffy-null genotype for the risk of clozapine-induced neutropenia. The study shows that individuals with the Duffy-null genotype have a significantly increased risk to develop clozapine-induced neutropenia, and stress the potential for a pharmacogenetic test for this genotype as part of the decision to follow BEN monitoring criteria.

Mol Psychiatry. 2019 Mar;24(3):328-337. doi: 10.1038/s41380-018-0335-7. Epub 2019 Jan 15.

A genome-wide association study in individuals of African ancestry reveals the importance of the Duffy-null genotype in the assessment of clozapine-related neutropenia.

Legge SE1Pardiñas AF1Helthuis M2Jansen JA2Jollie K2Knapper S3MacCabe JH4Rujescu D5Collier DA6O’Donovan MC1Owen MJ1Walters JTR7.



Individuals of African ancestry in the United States and Europe are at increased risk of developing schizophrenia and have poorer clinical outcomes. The antipsychotic clozapine, the only licensed medication for treatment-resistant schizophrenia, is under-prescribed and has high rates of discontinuation in individuals of African ancestry, due in part to increased rates of neutropenia. The genetic basis of lower neutrophil levels in those of African ancestry has not previously been investigated in the context of clozapine treatment. We sought to identify risk alleles in the first genome-wide association study of neutrophil levels during clozapine treatment, in 552 individuals with treatment-resistant schizophrenia and robustly inferred African genetic ancestry. Two genome-wide significant loci were associated with low neutrophil counts during clozapine treatment. The most significantly associated locus was driven by rs2814778 (β = -0.9, P = 4.21 × 10-21), a known regulatory variant in the atypical chemokine receptor 1 (ACKR1) gene. Individuals homozygous for the C allele at rs2814778 were significantly more likely to develop neutropenia and have to stop clozapine treatment (OR = 20.4, P = 3.44 × 10-7). This genotype, also termed “Duffy-null”, has previously been shown to be associated with lower neutrophil levels in those of African ancestry. Our results indicate the relevance of the rs2814778 genotype for those taking clozapine and its potential as a pharmacogenetic test, dependent on the outcome of additional safety studies, to assist decision making in the initiation and on-going management of clozapine treatment.