Agenesis of the Corpus Callosum with Peripheral Neuropathy (ACCPN) is a rare genetic disorder characterized by the corpus callosum's absence (total or partial). This structure connects the two hemispheres of the brain. Additionally, individuals with this condition may experience peripheral neuropathy, which involves damage to the peripheral nerves outside the brain and spinal cord.
Agenesis of the corpus callosum with peripheral neuropathy genetic testing is included in Diagnostiki Athinon Monogenic Diseases Genetic Testing along with approximetaly 100 other inherited diseases, including cystic fibrosis (71 mutations) and hereditary breast cancer (genes BRCA1 415 mutations & BRCA2 419 mutations).
It is a very rare syndrome with an autosomal recessive inheritance pattern that is particularly prevalent in the population originating from Quebec, Canada. The gene related to ACCPN is SLC12A6, which is involved in neuronal migration during the development of the corpus callosum in the fetal stage.
Critical features of Agenesis of the Corpus Callosum with Peripheral Neuropathy include:
- Agenesis of the Corpus Callosum (ACC): The corpus callosum is essential for communication between the brain's two hemispheres. In individuals with ACC, this structure is either completely absent or underdeveloped. ACC can lead to various neurological and cognitive symptoms, varying widely among affected individuals.
- Intellectual and Developmental Disabilities: ACC is often associated with intellectual and developmental disabilities. The severity of these disabilities can vary, ranging from mild to profound.
- Seizures: Individuals with ACC may be prone to seizures, which can further contribute to neurological symptoms.
- Peripheral Neuropathy: Peripheral neuropathy involves damage to the peripheral nerves, leading to weakness, numbness, and pain in the extremities. Peripheral neuropathy is an additional feature that distinguishes this condition from isolated ACC.
- Motor and Sensory Impairments: Peripheral neuropathy can result in motor and sensory impairments in the limbs, affecting an individual's ability to walk and perform daily activities.
Mutations in specific genes typically cause agenesis of the corpus callosum with peripheral neuropathy. The particular genes involved can vary among affected individuals.
Management of this condition is generally supportive and may include interventions such as physical therapy, occupational therapy, and educational support tailored to the individual's needs. Seizures, if present, may be treated with anticonvulsant medications.
Individuals with this condition and their families need to work closely with a multidisciplinary healthcare team, including neurologists, genetic counselors, and other specialists, to address the diverse range of symptoms and challenges associated with Agenesis of the Corpus Callosum with Peripheral Neuropathy.
ACCPN is a syndrome that follows an autosomal recessive inheritance pattern in which cases of compound heterozygosis (the presence of two distinct pathogenic variants in heterozygosis) have been observed. It is caused by alterations in the SLC12A6 gene encoding the KCC3 protein, a chloride and potassium ion transporter. This gene is mainly expressed in the brain, spinal cord, and dorsal root ganglia of the peripheral nervous system. It has been suggested that alterations in the SLC12A6 transporter could modify chloride concentrations in neurons, affecting neuronal activity and their response to the neurotransmitter GABA (gamma-aminobutyric acid).
One of the best-known pathogenic variants is c.2436+1del, which affects a splicing site. This variant is frequent in the French-Canadian population of the Saguenay and Lac-St-Jean regions of Quebec, Canada, where 1 in 23 inhabitants are carriers. However, the c.2436+1del and ACCPN variants have a very low prevalence in the rest of the world.
This genetic test of Agenesis of the Corpus Callosum with Peripheral Neuropathy analyzes the four most frequent pathogenic mutations of the SLC12A6 gene.
With the technique used for genetic testing, only the gene's specific mutations, which are the most important and frequent in the literature, are analyzed. However, it should be noted that there are likely other gene or chromosomal mutations in the gene to be tested, which cannot be identified with this method. Different analysis techniques can be used for these cases, such as, e.g., next-generation sequencing (NGS).
