Aarskog Syndrome: Deep Phenotyping and Genomic Landscape of a New Cohort Including Adult Patients

Abstract

Aarskog-Scott syndrome (AAS, MIM#305400) is an X-linked disorder characterized by recognizable facial features, short stature, and genitourinary and skeletal malformations. AAS is attributed to pathogenic variants in FGD1, and ~60 patients with a genetic diagnosis have been reported to date. We hereby present a molecularly confirmed cohort of 14 male AAS patients from 13 families. Among 14 patients, 12 were referred during childhood, while two were referred at adulthood due to infertility. Six out of 11 patients with available records had antenatal manifestations, comprising shortened tubular bones, growth restriction, polyhydramnios, pes equinovarus, increased nuchal translucency, fetal hypokinesia, echogenic intracardiac focus, and ambiguous genitalia. In addition to well-described AAS findings, distinctive features observed in multiple patients included variable skin findings (n = 5), renal malformations (n = 2), muscular build (n = 2), and infertility (n = 2). Cardiac (n = 4) and ocular manifestations (n = 6) were identified at significantly higher rates than previously reported. This cohort also presents new patients with osteochondritis dissecans and oligo/azoospermia, providing further evidence to acknowledge these once-reported findings as part of the disease spectrum. Eleven different FGD1 variants, including seven novel ones, were identified through targeted FGD1 sequencing. Two variants were found to be recurrent, detected in two independent families. Our study provides additional insights into the clinical and genotypic landscape of AAS through the largest molecularly confirmed cohort, including two adult patients.

Keywords: Aarskog syndrome; Aarskog‐Scott syndrome; FGD1; faciogenital dysplasia; short stature.

FIGURE 1

Clinical images of the patients and the identified FGD1 variants. (A‐D) shows pediatric patients with AAS. (A) corresponds to P1 at 3 years, while (B–D) illustrate the evolving phenotype of P6, photographed at 3 years (B), 13 years (C), and 16 years 3 months (D). (E–G) presents adult patients. Note that the overall facial gestalt is more recognizable in prepubertal patients, and follow‐up of P6 (B–D) demonstrated that dysmorphic features became less apparent over time. Hand photographs of P6 taken 10 years apart (H, I) revealed a similar pattern, with brachydactyly and interdigital webbing more pronounced in early childhood. Additional findings include non‐fixed swan‐neck deformity of the fingers (J), gynecomastia, pectus excavatum (K), and uplifted earlobes (L). Schematic diagram of the FGD1 protein (M) showing the variants identified in this study. Novel variants are depicted in bold, while recurrent variants are marked with an asterisk (*).