rs587777380 — DYRK1B H90P / H90R

DYRK1B H90P — The Metabolic Syndrome Gene

DYRK1B (Dual-Specificity Tyrosine Phosphorylation-Regulated Kinase 1B) is a serine/threonine kinase that plays a pivotal role in adipogenesis, glucose homeostasis, and hedgehog/Wnt signaling pathways. When functioning normally, DYRK1B helps restrain fat cell differentiation and maintain metabolic balance. The H90P variant disrupts a critical structural element of the kinase, triggering a cascade of metabolic consequences that manifest as AOMS3¹¹ AOMS3
Abdominal Obesity-Metabolic Syndrome 3, OMIM #615812, a rare autosomal dominant condition causing severe early-onset metabolic syndrome.

The Mechanism

The H90P mutation replaces histidine with proline at position 90 of the protein, within the DYRK homology (DH) box²² DYRK homology (DH) box
A conserved structural element immediately preceding the catalytic domain, critical for proper kinase folding through tyrosine autophosphorylation. This box normally stabilizes interactions with the catalytic domain during protein maturation. The substitution impairs tyrosine autophosphorylation (reduced ~80% versus wild-type), causing mutant DYRK1B to misfold and accumulate in detergent-insoluble cytoplasmic aggregates. The result is a net loss of functional DYRK1B activity.

Without adequate DYRK1B function, two main pathological effects follow: enhanced adipogenesis — preadipocytes differentiate more readily into fat cells, leading to accelerated visceral fat accumulation — and impaired glucose regulation — hepatic glucose-6-phosphatase expression rises, driving excess hepatic glucose output and contributing to frank type 2 diabetes. Downstream, the RAS–RAF–MEK pathway is dysregulated, and suppression of hedgehog and Wnt signaling further promotes adipogenic commitment of precursor cells.

The Evidence

The H90P variant was first described in 2014³³ first described in 2014
Keramati AR et al. A form of the metabolic syndrome associated with mutations in DYRK1B. N Engl J Med. 2014;370(20):1909-19 through genetic linkage analysis and whole-exome sequencing of three large Iranian families with autosomal dominant metabolic syndrome. H90P co-segregated with disease in an ethnically distinct family alongside the R102C mutation, producing an identical phenotype: early-onset central obesity, type 2 diabetes, hypertension, and coronary artery disease (myocardial infarction between ages 50–60). No unaffected carrier was identified in any family, suggesting high penetrance.

Molecular characterization⁴⁴ Molecular characterization
Abu Jhaisha S et al. DYRK1B mutations associated with metabolic syndrome impair the chaperone-dependent maturation of the kinase domain. Sci Rep. 2017;7(1):7602 confirmed that H90P — unlike the structurally intact mature kinase — fails to properly autophosphorylate on tyrosine. The mutant protein relies abnormally on the HSP90–CDC37 chaperone complex for stability, rendering it sensitive to HSP90 inhibition. This chaperone dependency is a therapeutic vulnerability that has been proposed as a drug target.

A 2024 Diabetes Care study⁵⁵ 2024 Diabetes Care study
Folon L et al. Pathogenic, Total Loss-of-Function DYRK1B Variants Cause Monogenic Obesity Associated With Type 2 Diabetes. Diabetes Care. 2024 across 9,353 participants quantified the effect: pathogenic DYRK1B loss-of-function variants were associated with an 8.0-unit higher BMI (OR 7.9 for obesity) and OR 4.8 for type 2 diabetes. The same study confirmed that H90P-class variants cause monogenic obesity, a clinically distinct entity from polygenic common obesity.

What This Means Clinically

AOMS3 is frequently misdiagnosed. A 2024 case report⁶⁶ 2024 case report
Abdominal Obesity-Metabolic Syndrome 3 Misclassified as Type 1 Diabetes Mellitus. 2024 documented a patient treated with 225 units of insulin daily for 15 years before the DYRK1B mutation was identified. Switching to oral agents (metformin, pioglitazone, dapagliflozin) plus semaglutide reduced HbA1c from 13% to 7% within 6 months — a result insulin alone had never achieved. DYRK1B carriers respond better to insulin-sensitizing agents and GLP-1 receptor agonists than to exogenous insulin.

Because this is an autosomal dominant condition, each first-degree relative of a carrier has a 50% chance of inheriting the variant. Early identification before metabolic complications emerge allows preventive intervention.

H90R — The Second Allele at This Codon

This locus is multi-allelic: in addition to H90P (T>G), a T>C change at the same position produces H90R (His90Arg). H90R has not been individually characterised in cell-based assays, but its structural logic is equivalent — arginine, like proline, disrupts the local backbone geometry of the DH box required for tyrosine autophosphorylation during kinase maturation. Population data (gnomAD v4 exomes, ~3 alleles in 800,000) confirms the same extreme rarity as H90P. H90R is classified as likely pathogenic by structural inference; clinical management for carriers is identical to H90P.

Interactions

H90P and H90R act at the same codon as the R102C variant (encoded by a distinct mutation in the same DYRK1B gene at codon 102). All three disrupt the DH box and produce clinically indistinguishable AOMS3. Functional studies on H90P and R102C show overlapping mechanisms — impaired DH-box-mediated kinase maturation, enhanced chaperone dependency, and downstream adipogenic dysregulation — making them phenotypic equivalents despite different amino acid substitutions.