A case of Ververi-Brady syndrome due to QRICH1 loss of function and the literature review

A novel variant in the QRICH1 gene was identified in a patient with severe developmental delay

BACKGROUND

QRICH1 encodes the glutamine-rich protein 1, which contains one caspase activation recruitment domain and is likely to be involved in apoptosis and inflammation. However, the function of the QRICH1 gene was largely unknown. Recently, several studies have reported de novo variants in QRICH1, and the variants have been associated with Ververi-Brady syndrome characterized by developmental delay, nonspecific facial dysmorphism, and hypotonia.

MATERIALS AND METHODS

Whole exome sequencing, clinical examinations, and functional experiments were performed to identify the etiology of our patient.

RESULTS

Here, we added another patient with severe growth retardation, atrial septal defect, and slurred speech. Whole exome sequencing identified a novel truncation variant in the QRICH1 gene (MN_017730.3: c.1788dupC, p.Tyr597Leufs*9). Furthermore, the functional experiments confirmed the effect of genetic variation.

CONCLUSION

Our findings expand the QRICH1 variant spectrum in developmental disorders and provide evidence for the application of whole exome sequencing in Ververi-Brady syndrome.

The clinical and molecular spectrum of QRICH1 associated neurodevelopmental disorder

De novo variants in QRICH1 (Glutamine-rich protein 1) has recently been reported in 11 individuals with intellectual disability (ID). The function of QRICH1 is largely unknown but it is likely to play a key role in the unfolded response of endoplasmic reticulum stress through transcriptional control of proteostasis. In this study, we present 27 additional individuals and delineate the clinical and molecular spectrum of the individuals (n = 38) with QRICH1 variants. The main clinical features were mild to moderate developmental delay/ID (71%), nonspecific facial dysmorphism (92%) and hypotonia (39%). Additional findings included poor weight gain (29%), short stature (29%), autism spectrum disorder (29%), seizures (24%) and scoliosis (18%). Minor structural brain abnormalities were reported in 52% of the individuals with brain imaging. Truncating or splice variants were found in 28 individuals and 10 had missense variants. Four variants were inherited from mildly affected parents. This study confirms that heterozygous QRICH1 variants cause a neurodevelopmental disorder including short stature and expands the phenotypic spectrum to include poor weight gain, scoliosis, hypotonia, minor structural brain anomalies, and seizures. Inherited variants from mildly affected parents are reported for the first time, suggesting variable expressivity.

The Pancreatic ß-cell Response to Secretory Demands and Adaption to Stress

Pancreatic β cells dedicate much of their protein translation capacity to producing insulin to maintain glucose homeostasis. In response to increased secretory demand, β cells can compensate by increasing insulin production capability even in the face of protracted peripheral insulin resistance. The ability to amplify insulin secretion in response to hyperglycemia is a critical facet of β-cell function, and the exact mechanisms by which this occurs have been studied for decades. To adapt to the constant and fast-changing demands for insulin production, β cells use the unfolded protein response of the endoplasmic reticulum. Failure of these compensatory mechanisms contributes to both type 1 and 2 diabetes. Additionally, studies in which β cells are "rested" by reducing endogenous insulin demand have shown promise as a therapeutic strategy that could be applied more broadly. Here, we review recent findings in β cells pertaining to the metabolic amplifying pathway, the unfolded protein response, and potential advances in therapeutics based on β-cell rest.