Homozygous ADCY5 mutation causes early-onset movement disorder with severe intellectual disability

Microdeletion 3q13.33-3q21.2: A Rare Cause of Neurodevelopmental Disorder

Chromosomal sub-microscopic imbalances, such as microdeletions and microduplications, are associated with multiple genetic disorders. Here, we illustrate microdeletion 3q13.33q21.2 might be responsible for neurodevelopmental disorder in two patients. There are two patients with neurodevelopmental disorder in a family of seven. We used chromosomal microarray analysis to identify the microdeletion 3q13.33q21.2. Next-generation sequencing was utilized to exclude the presence of allelic mutations within the microdeletion region 3q13.33q21.2, which may have a potential role in the development of disease in patients affected with secondary genetic alterations. Patient 4 was diagnosed with dilated left third ventricle, neurodevelopmental disorder, and mild abnormalities in electroencephalogram through a series of clinical examinations. Patient 6 was diagnosed with attention deficit hyperactivity disorder, short stature, intellectual disability, and concurrent epilepsy. By investigating the 3q13.33q21.2 band of the University of California, Santa Cruz database, we screened out the genes related to developmental delay and intellectual disability, including ADCY5 SEMA5B andKPNA1, which were highly suspected to be related to intelligence. This region also involves CASR, a gene that has been reported to be associated with epilepsy. The ADCY5 and SEMA5B genes may be key genes to cause neurodevelopmental disorder. Abnormal expression of the CASR gene may lead to the occurrence of epilepsy.

Scoping Review on ADCY5-Related Movement Disorders

Background

Adenylyl cyclase 5 (ADCY5)-related movement disorder (ADCY5-RMD) is a rare, childhood-onset disease resulting from pathogenic variants in the ADCY5 gene. The clinical features, diagnostic options, natural history, and treatments for this disease are poorly characterized and have never been established through a structured approach.

Objective

This scoping review attempts to summarize all available clinical literature on ADCY5-RMD.

Methods

Eighty-seven articles were selected for inclusion in this scoping review. The majority of articles identified were case reports or case series.

Results

These articles demonstrate that patients with ADCY5-RMD suffer from permanent and/ or paroxysmal hyperkinetic movements. The paroxysmal episodes can be worsened by environmental triggers, in particular the sleep-wake transition phase in the early morning. Occurrence of nocturnal paroxysmal dyskinesias and perioral twitches are highly suggestive of the diagnosis when present. In the majority of patients intellectual capacity is preserved. ADCY5-RMD is considered a non-progressive disorder, with inter-individual variations in evolution with aging. Somatic mosaicism, mode of inheritance and the location of the mutation within the protein can influence phenotype.

Conclusions

The current evidence for therapeutic options for ADCY5-RMD is limited: caffeine, benzodiazepines and deep brain stimulation have been consistently reported to be useful in case reports and case series.

Expression and functions of adenylyl cyclases in the CNS

Adenylyl cyclases (ADCYs), by generating second messenger cAMP, play important roles in various cellular processes. Their expression, regulation and functions in the CNS, however, remain largely unknown. In this review, we first introduce the classification and structure of ADCYs, followed by a discussion of the regulation of mammalian ADCYs (ADCY1-10). Next, the expression and function of each mammalian ADCY isoform are summarized in a region/cell-specific manner. Furthermore, the effects of GPCR-ADCY signaling on blood-brain barrier (BBB) integrity are reviewed. Last, current challenges and future directions are discussed. We aim to provide a succinct review on ADCYs to foster new research in the future.