A novel frameshift mutation in the FGD1 gene causing Aarskog-Scott syndrome patient with hypogonadism: a case report

Aarskog-Scott syndrome (AAS) is most commonly inherited as an X-linked recessive genetic disease caused by FGD1 mutations. AAS patients are most frequently male, and the clinical manifestations of facial abnormalities, skeletal deformities, and abnormal genitalia comprise a characteristic triad of diagnostic features. The results on the clinical and molecular analysis of a family that reveals a novel FGD1 gene frameshift mutation in an 11-year-old boy displaying bilateral cryptorchidism associated with hypogonadism are reported here. This patient exhibited a characteristic triad of diagnostic features of ASS, including short stature, facial abnormalities, joint laxity, and typical scrotal fold. Whole-exome sequencing revealed the novel hemizygous mutation c.500delA in exon 3 of the patient's FGD1 gene, resulting after a frameshift in the Tyr167 residue, while his mother is heterozygous of the same variant. Further in silico studies were performed to identify the pathological consequence of this gene mutation. Thus, our study shows that frameshifts disrupting the RhoGEF gene domain of FGD1 represent the most prevalent causal mutations underlying AAS and expand the phenotypic and mutational spectra of this disease. Improved understanding of the phenotypic and pathological heterogeneity accompanying FGD1 mutation can greatly enhance the clinical prognostic capabilities in the future and aid genetic counseling for AAS patients.