A Missense Mutation in TRPS1 in a Family with Trichorhinophalangeal Syndrome Type III Accompanied by Ankylosing Spondylitis

The Clinical and Molecular Spectrum of Trichorhinophalangeal Syndrome Types I and II in a Turkish Cohort Involving 22 Patients

OBJECTIVE

Trichorhinophalangeal syndrome is a rare autosomal dominant disorder characterized by distinctive craniofacial and skeletal abnormalities. This study aimed to delineate the trichorhinophalangeal syndrome phenotype and to compare the clinical and molecular findings between trichorhinophalangeal syndrome types I and II.

MATERIALS AND METHODS

A total of 22 trichorhinophalangeal syndrome patients aged 0.9-45 years from 17 families were enrolled. Nineteen patients were diagnosed with trichorhin ophalangeal syndrome I and 3 with trichorhinophalangeal syndrome II. Genetic analyses were made by TRPS1 sequencing and/or chromosomal microarray analyses.

RESULTS

A novel frameshift variant (c.531_532del), a known missense variant, and whole-gene deletions were the pathogenic TRPS1 variants detected in trichorhinophalangeal syndrome I. Three trichorhinophalangeal syndrome II patients had large deletions with variable breakpoints involving the TRPS1-EXT1 interval. All patients had the typical craniofacial findings of trichorhinophalangeal syndrome such as a pear-shaped nose, long philtrum, and thin upper lip, as well as cone-shaped epiphyses. Sparse hair and eyebrows (20/22), short metacarpals and metatarsals (20/22), and small hands (19/22) were common. While craniofacial and limb abnormalities were similar in trichorhinophalangeal syndrome I and II, 3 of 19 trichorhinophal angeal syndrome I patients had mild, and 2 of 3 trichorhinophalangeal syndrome II patients had severe intellectual disability. Three trichorhinophalangeal syndrome II patients including the patient with the EXT1 deletion beginning from exon 2 had exostoses. In trichorhinophal angeal syndrome II, although microdeletion sizes and facial or skeletal features were not correlated, patients with larger deletions had severe intellectual disability.

CONCLUSION

This study has expanded the existing knowledge on the phenotype-genotype spectrum in trichorhinophalangeal syndrome. We suggest including the EXT1 gene partially in the minimal critical region for trichorhinophalangeal syndrome II.

A 15-Year-Old Girl with Trichorhinophalangeal Syndrome Type 1 with Non-ossifying Fibroma in Femur: A Case Report

Introduction: Trichorhinophalangeal syndrome (TRPS) is a sporadic autosomal dominant disorder with approximately 200 reported cases worldwide. We aimed to report a 15-year-old girl with TRPS type 1 (TRPS1) and the second reported case with a rare non-ossifying fibroma (NOF) in the distal part of her left femur. Case Presentation: We introduce a 15-year-old girl who presented to the outpatient rheumatology clinic at 17 Shahrivar Children's Hospital, Rasht, Iran, with the chief complaint of osteoarticular pain and bone deformities. She had sparse hair, a recession of the fronto-temporal hairline, and unusually thick eyebrows at the medial and abnormal sparseness of the lateral margins. Physical examination of the limbs revealed short fingers and toes with proximal interphalangeal (PIP) ulnar deviation of the second and third fingers in both hands. Shortness of the fourth fingers, especially in the right hand, and the swelling of the PIP joints of both hands were prominent. Genetic analysis showed deletion mutation in the TRPS1 gene in chromosome 8q24 compatible with TRPS1. Conclusions: Several symptoms and signs, including distinctive craniofacial features and ectodermal and skeletal abnormalities, are used for proper TRPS diagnosis. A correct and on-time diagnosis is essential to perform supportive care for the patient to prevent morbidities. Bone lesions, such as NOF1, can also be presented in TRPS1 patients and may be correlated with TRPS1 mutation. Further investigations are required on the association of the TRPS gene with NOF bone lesions.