DeCure for Treacher Collins syndrome 3

A 2009 review of 50 patients treated over 30 years at the Australian Craniofacial Unit describes a three-epoch management protocol. From birth to age 2, airway and feeding were the main focus: four patients required tracheostomy, one of whom died, and the others received mandibular distraction. Eleven patients (23%) required cleft palate repair. From age 2 to 12, speech therapy and educational integration were critical, and upper face reconstruction was performed with bone grafts or vascularised bone flaps, both of which required repeat grafting later. From age 13 to 18, orthognathic surgery was performed, with further revision and bone grafting around age 18. Patients generally reported being happy with their appearance, and with few exceptions completed education, gained employment, and felt socially accepted.

A 2013 cephalometric study of 20 unoperated patients with Treacher Collins syndrome aged 5 to 17 years (mean 8.8 years) quantified the skeletal dysmorphology. Compared to age-matched and sex-matched controls, the patients had decreased anterior, posterior, and total cranial base lengths, a reduced cranial base angle, a deficient maxilla in anteroposterior dimension that was positioned posteriorly, and decreased anterior and posterior facial heights. Lower face height was increased while total face height was decreased. The mandible was characteristically small in body length and total mandibular length, with deficient maximum ramus width, increased mandibular plane angle and gonial angle, and retropositioning. The maxillary and functional occlusal planes were tipped upwards posteriorly.

The genetic basis is mutations in TCOF1, which encodes the protein treacle. A 2002 screening study confirmed that the majority of pathogenic mutations are small deletions and insertions causing frameshifts predicted to truncate the protein. More than 50% of described mutations cluster in five exons (10, 15, 16, 23, and 24), which are considered mutational hot spots. A commonly occurring 5 bp deletion in exon 24 is found in approximately 16% of families. No correlation exists between mutation type or localisation and phenotypic expression. A 2009 report identified a de novo synonymous mutation, c.3612A > C, that caused mis-splicing of a constitutive exon and haploinsufficiency, highlighting the need for clinical and pedigree evaluation to interpret sequence alterations. A 2004 case documented a novel de novo nonsense mutation 2731C --> T (Arg911Stop) in a patient with classic TCS plus craniosynostosis, choanal atresia, and esophageal regurgitation. A 2016 report described a heterozygous insertion c.2013_2014insG causing premature termination at 680aa.

What is still missing is a drug that targets the underlying haploinsufficiency of TCOF1 or the downstream effects on neural crest cell development. No pharmacological intervention is described in any of these abstracts. The management remains entirely surgical and supportive. A therapy would require a clear molecular target, a delivery method that reaches developing craniofacial structures in utero or early postnatally, and a trial design that can measure meaningful functional and aesthetic outcomes in a rare, phenotypically variable condition. Patient stratification by mutation type and severity of skeletal dysplasia would be necessary, and funding for such a trial would be difficult given the small patient population.