Coffin-Siris syndrome - one syndrome with various genetic variants and phenotypes

Coffin-Siris syndrome encompasses a group of genetic disorders with a wide spectrum of phenotypic features, characterized by varying degrees of intellectual disability, developmental delay, and other clinical signs. Among the most common features are the aplasia or hypoplasia of the distal phalanx or nail of the fifth finger and coarse facial features. The aim of the work is to increase awareness among physicians about the diagnosis of Coffin-Siris syndrome and expand knowledge of the spectrum of clinical features of the disease based on the presentation of two clinical cases. We presented two clinical cases of Coffin-Siris syndrome caused by variants in the SMARCA4 and DPF2 genes. In both cases, there is a delay in speech development, cognitive impairments of varying severity, behavioral changes, characteristic dysmorphic features, and changes in the hands and/or feet, especially in the little finger. Distal phalanx nail hypoplasia of the fifth finger was present in the case associated with a variant in the DPF2 gene. In the patient with a variant in the SMARCA4 gene, flexion deformity of the little finger and broad palms were observed. Pachydermodactyly and a congenital kidney defect were also diagnosed in this patient. Thus, genetic diagnosis allows for timely identification, preventing complications and avoiding unnecessary investigations. Accumulating clinical data on rare diseases and their systematization contribute to research development and, subsequently, to determining optimal therapeutic approaches. The identified genetic factor in the proband ensures genetic counseling for the family and determining risk indicators for pathologies in offspring. The research was carried out in accordance with the principles of the Helsinki Declaration. The informed consent of the patient was obtained for conducting the studies. No conflict of interests was declared by the authors.