| Literature DB >> 29145497 |
Douglas R Smith1, Christine M Stanley1, Theodore Foss1, Richard G Boles1, Kevin McKernan1.
Abstract
Rare genetic variants in the core endocannabinoid system genes CNR1, CNR2, DAGLA, MGLL and FAAH were identified in molecular testing data from 6,032 patients with a broad spectrum of neurological disorders. The variants were evaluated for association with phenotypes similar to those observed in the orthologous gene knockouts in mice. Heterozygous rare coding variants in CNR1, which encodes the type 1 cannabinoid receptor (CB1), were found to be significantly associated with pain sensitivity (especially migraine), sleep and memory disorders-alone or in combination with anxiety-compared to a set of controls without such CNR1 variants. Similarly, heterozygous rare variants in DAGLA, which encodes diacylglycerol lipase alpha, were found to be significantly associated with seizures and neurodevelopmental disorders, including autism and abnormalities of brain morphology, compared to controls. Rare variants in MGLL, FAAH and CNR2 were not associated with any neurological phenotypes in the patients tested. Diacylglycerol lipase alpha synthesizes the endocannabinoid 2-AG in the brain, which interacts with CB1 receptors. The phenotypes associated with rare CNR1 variants are reminiscent of those implicated in the theory of clinical endocannabinoid deficiency syndrome. The severe phenotypes associated with rare DAGLA variants underscore the critical role of rapid 2-AG synthesis and the endocannabinoid system in regulating neurological function and development. Mapping of the variants to the 3D structure of the type 1 cannabinoid receptor, or primary structure of diacylglycerol lipase alpha, reveals clustering of variants in certain structural regions and is consistent with impacts to function.Entities:
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Year: 2017 PMID: 29145497 PMCID: PMC5690672 DOI: 10.1371/journal.pone.0187926
Source DB: PubMed Journal: PLoS One ISSN: 1932-6203 Impact factor: 3.240
Association of mouse knockout phenotypes with rare variants in CNR1 and DAGLA.
| Gene | Phenotype | Cases | Controls | OR | P-value |
|---|---|---|---|---|---|
| Pain sensitivity | 9/22 | 156/950 | 3.5 | 0.036 | |
| Anxiety | 7/22 | 122/950 | 3.2 | 0.131 | |
| Memory disorder | 3/22 | 1/950 | 150 | 0.0003 | |
| Sleep disorder | 6/22 | 33/950 | 10.4 | 0.001 | |
| Urinary frequency | 2/22 | 19/950 | 4.9 | 0.301 | |
| Seizures | 11/22 | 402/950 | 1.4 | 1.000 | |
| Hearing loss | 1/22 | 31/950 | 1.4 | 1.000 | |
| Pain sensitivity and anxiety | 5/22 | 47/950 | 5.7 | 0.030 | |
| Sleep disorder and anxiety | 4/22 | 8/950 | 26.2 | 0.001 | |
| Pain sensitivity and memory disorder | 3/22 | 1/950 | 150 | 0.000 | |
| Pain sensitivity, memory and sleep disorder | 3/22 | 1/950 | 150 | 0.000 | |
| Pain sensitivity, anxiety and memory disorder | 2/22 | 0/950 | N/A | 0.003 | |
| Pain sensitivity, anxiety, memory and sleep disorder | 2/22 | 0/950 | N/A | 0.003 | |
| Pain sensitivity and sleep disorder | 3/22 | 7/950 | 21.3 | 0.005 | |
| Anxiety | 2/35 | 177/950 | 0.26 | 0.211 | |
| Neurodevelopmental disorder | 27/35 | 448/950 | 3.78 | 0.001 | |
| Anxiety and neurodevelopmental disorder | 2/35 | 98/950 | 0.53 | 1.000 | |
| Seizures | 30/35 | 595/950 | 3.84 | 0.032 | |
| Seizures and neurodevelopmental disorder | 22/35 | 332/950 | 3.15 | 0.003 |
*For each gene, the phenotypes that were evaluated are listed along with the number of cases or controls in which that phenotype was present out of the total number. Also listed are the odds ratio (OR), and P-values corrected for multiple testing. Confidence intervals for the odds ratios are provided in an extended version of the table in the supporting information (S7 Table).
Fig 1A. Depiction of the x-ray crystal structure of the type I cannabinoid receptor with bound agonist AM11542 from PDB ID 5XRA. The location of rare coding variants that could be mapped to the structure are shown by magenta dots, with annotations indicating the amino acid substitutions and the cannabinoid binding site. B. The location of rare coding variants relative to domains of the enzyme and regulatory phosphorylation sites are indicated, based on NCBI Reference Sequence: NP_001153731.1. Red dot: rare variant; T (light green shading): transmembrane domain; P (blue vertical lines): phosphorylation sites.
Fig 2Mapping of rare variants to diacylglycerol lipase alpha.
The location of rare coding variants relative to domains of the enzyme and regulatory phosphorylation sites are indicated, based on NCBI Reference Sequence: NP_006124.1. Red dot: rare variant; purple dots: two variants present in one subject; T (light green shading): transmembrane domain; light blue shading: lipase domain; A (purple shading): Active site; N (magenta shading): Nucleophilic elbow; blue vertical lines: phosphorylation sites.