A rare homozygous ALX4 mutation in a Bangladeshi girl with frontonasal dysplasia type-2 (FND2)

Background: Frontonasal dysplasia type-2(FND2), a rare phenotypically variable and heterogeneous developmental anomaly resulting from mutation of the ALX4 gene, is primarily characterized by malformation of the skull and facial skeleton. This study was designed to showcase a clinical, imaging, and genetic analysis of FND2 in a consanguineous family of Bangladeshi origin.

Methodology: Clinical imaging and whole genome sequencing of mother, father and patient was done by using Nextera DNA flex library preparation kit (Illumina, USA) using Novaseq 6000 next generation sequencer to find out ALX4 mutation which causes FND2 in patient.

Result: We report the clinical as well as molecular findings in an 8-year-old girl with FND2. The child presented with various characteristic features of skull and facial anomalies associated with FND 2 along with numerous other features many of which have not been described in previous literature. The parents also showed some key clinical, radiological, and genetic features of FND 2. The whole genome sequencing (WGS) revealed homozygosity for a 793C-T transition in the ALX4 gene, which resulted in premature termination at codon 265 (p.Arg265Ter). Both of her parents were heterozygous carriers of ALX4 mutation.

Conclusions: This is the first report that associates clinical, imaging, and genomics analyses in a Bangladeshi patient for better understanding the disease FND2. These results will facilitate diagnosis and genetic counseling of the future FND2 patients.