Clinical and genetic characteristics of patients with MN1 gene dysfunction after the two clinical case reports

MN1 gene is localized in the q12.1 region of the Chromosome 22, consists of two exons and encodes a protein of 1320 amino acids. In 2020 it was for the first time shown that dysfunction of the MN1 gene causes a specific disease, CEBALID syndrome, which is characterized by malformations of the central nervous system and craniofacial skeleton. There are also isolated reports that overlapping microdeletions of 22q12.1, including the entire sequence of the MN1 gene, are associated with various clinical phenotypes, including developmental anomalies of the nervous system, facial dysmorphia and congenital heart defects. Authors represent the two new clinical case reports of dysfunction of the MN1 gene caused by a heterozygous deletion of 22q12.1 and a pathogenic variant of the nucleotide sequence in exon 2 of the MN1 gene, which were diagnosed in two patients with different phenotype anomalies. Conclusion: the variability of clinical features among the two presented cases was caused by different types of genetic variants. Deletion of the chromosomal region 22q12.1 leads to less pronounced clinical symptoms and difficulties in diagnosis.