Multiple synostoses syndrome: Clinical report and retrospective analysis

The fundamentals of fibroblast growth factor 9

Fibroblast growth factor 9 (FGF9) was first identified during a screen for factors acting on cells of the central nervous system (CNS). Research over the subsequent two decades has revealed this protein to be a critically important and elegantly regulated growth factor. A hallmark control feature is reciprocal compartmentalization, particularly during development, with epithelium as a dominant source and mesenchyme a prime target. This mesenchyme selectivity is accomplished by the high affinity of FGF9 to the IIIc isoforms of FGFR1, 2, and 3. FGF9 is expressed widely in the embryo, including the developing heart and lungs, and more selectively in the adult, including the CNS and kidneys. Global Fgf9-null mice die shortly after birth due to respiratory failure from hypoplastic lungs. As well, their hearts are dilated and poorly vascularized, the skeleton is small, the intestine is shortened, and male-to-female sex reversal can be found. Conditional Fgf9-null mice have revealed CNS phenotypes, including ataxia and epilepsy. In humans, FGF9 variants have been found to underlie multiple synostoses syndrome 3, a syndrome characterized by multiple joint fusions. Aberrant FGF9 signaling has also been implicated in differences of sex development and cancer, whereas vascular stabilizing effects of FGF9 could benefit chronic diseases. This primer reviews the attributes of this vital growth factor.

Congenital Proximal Radioulnar Synostosis in an Elite Athlete–Case Report

Background and Objectives: Proximal radioulnar synostosis (PRUS) is the most frequent congenital forearm disorder, although the prevalence in the general population is rare with a few hundred cases reported. Pfeiffer, Poland, Holt–Oram, and other serious congenital syndromes contain this abnormality. Non-syndromic cases with isolated PRUS very often exhibit as SMAD6, NOG genes variants, or sex chromosome aneuploidy. A subgroup of patients with haematological abnormalities presents with HOXA11 or MECOM genes variants. Case report: We present a non-syndromic adult elite ice-hockey player with unilateral proximal radioulnar synostosis of the left forearm. In early childhood he was able to handle the hockey stick only as a right-handed player and the diagnosis was set later at the age of 8 years due to lack of supination. Cleary–Omer Type III PRUS was found on x-ray with radial head hypoplasia and mild osteophytic degenerative changes of humeroulnar joint. Since the condition had minimal impact on sports activities, surgical intervention was not considered. The player continued his ice-hockey career at the top level and joined a national team for top tournaments. Upper extremity function assessment with questionnaires and physical testing resulted in minimal impairment. The most compromised tool was the Failla score with 10 points from a total of 15. Genetic testing with Sanger sequencing revealed no significant pathogenic variant in SMAD6, NOG, and GDP5 genes. No potentially pathogenic copy number variants were detected by array-based comparative genomic hybridization. Conclusions: In the reported case, the ability of an athlete to deal with an anatomic variant limiting the forearm supination is demonstrated. Nowadays, a comprehensive approach to rule out more complex musculoskeletal impairment and family burden is made possible by evolving genetics.

Clinical observation and genetic analysis of a SYNS1 family caused by novel NOG gene mutation

Objective

Analyze the clinical and genetic characteristics of a rare Chinese family with Multiple synostoses syndrome and identify the causative variant with the high‐throughput sequencing approach.

Methods

The medical history investigation, physical examination, imaging examination, and audiological examination of the family members were performed. DNA samples were extracted from the family members. The candidate variant was identified by performing whole‐exome sequencing of the proband, then verified by Sanger sequencing in the family.

Results

The family named HBSY‐018 from Hubei province had 18 subjects in three generations, and six subjects were diagnosed with conductive or mixed hearing loss. Meanwhile, characteristic features including short philtrum, hemicylindrical nose, and hypoplastic alae nasi were noticed among those patients. Symptoms of proximal interdigital joint adhesion and inflexibility were found. The family was diagnosed as Multiple synostoses syndrome type 1 (SYNS1).The inheritance pattern of this family was autosomal dominant. A novel mutation in the NOG gene c.533G>A was identified by performing whole‐exome sequencing of the proband. The substitution of cysteine encoding 178th position with tyrosine (p.Cys178Tyr) was caused by this mutation, which was conserved across species. Co‐segregation of disease phenotypes was demonstrated by the family verification.

Conclusion

The family diagnosed as SYNS1 was caused by the novel mutation (c.533G>A) of NOG. The combination of clinical diagnosis and molecular diagnosis had improved the understanding of this rare disease and provided a scientific basis for genetic counseling in the family.

Treacher Collins syndrome: Clinical report and retrospective analysis of Chinese patients

Background

Treacher Collins syndrome‐1 (TCS1; OMIM# 154500) is a rare autosomal dominant disease that is defined by congenital craniofacial dysplasia. Here, we report four sporadic and one familial case of TCS1 in Chinese patients with clinical features presenting as hypoplasia of the zygomatic complex and mandible, downslanting palpebral fissures, coloboma of the lower eyelids, and conductive hearing loss.

Materials and Methods

Audiological, radiological, and physical examinations were performed. Targeted next‐generation sequencing (NGS) was performed to examine the genetics of this disease in five probands, and Sanger sequencing was used to confirm the identified variants. A literature review discusses the pathogenesis, treatment, and prevention of TCS1.

Results

We identified a novel insertion of c.939_940insA (p.Gly314Argfs*35; NM_001135243.1), a novel deletion of c.1766delC (p.Pro589Leufs*7), two previously reported insertions of c.1999_2000insC (p.Arg667Profs*31) and c.4218_4219insG (p.Ser1407Valfs*23), and one previously reported deletion of c.4369_4373delAAGAA (p.Lys1457Glufs*12) in the TCOF1 gene. All five cases exhibited a degree of interfamilial and intrafamilial phenotypic variability. A review of the literature revealed no clear evidence of a genotype–phenotype correlation in TCS1.

Conclusion

Our results expand the variant spectrum of TCOF1 and highlight that NGS is essential for the diagnosis of TCS and that genetic counseling is beneficial for guiding prevention.