Xia-Gibbs Syndrome: A Review of Literature

Abstract

Xia-Gibbs syndrome (XGS) is a rare genetic disorder that has been discovered as a distinct clinical entity in the recent past. The occurrence has been attributed to the mutation of AT Hook DNA binding motif Containing 1 (AHDC1) gene that is carried on chromosome 1p36. The concerned gene participates in deoxyribonucleic acid (DNA) repair apart from other crucial functions. The mutation results in dysfunction that leads to neurodevelopmental delay. The spectrum of manifestations constitutes intellectual disabilities, hypotonia, expressive language delay, sleep difficulties, and short stature. Dysmorphic facial features include depressed nasal bridge, hypertelorism, down-slanting or up-slanting palpebral fissures, horizontal eyebrows, dysplastic dentition, thin upper lip vermilion, and micrognathia. The phenotype is still expanding. The condition may range from mild to severe dysfunction depending on the area and site of genetic aberration but variation is evident. Thus, the correlation between genotype and phenotype is largely unclear. XGS should be considered as a differential diagnosis for patients presenting with intellectual as well as developmental disabilities. Whole-exome sequencing (WES) is the genetic test that is largely used for the confirmation of diagnosis. Less is known about the natural history as only a few adults with XGS have been documented in the literature. Age-appropriate cancer screening is recommended for patients with XGS as the gene mutation alters DNA repair mechanisms that may trigger tumour formation. The management of patients diagnosed with XGS is an area that needs investigation. Though use of growth hormone replacement therapy and physiotherapy intervention have been reported as effective in previous studies, research on effective means of care of these patients is warranted on a larger number of patients. We present a review of current literature on what is known about XGS that would facilitate to identify knowledge gaps for paving a way for further studies. This, in turn, will help in provision of early and effective rehabilitation services for patients with XGS.

Keywords: growth hormone replacement therapy; neurodevelopmental treatment; paediatric neurology; physiotherapy; rare genetic disorder; rehabilitation; whole-exome sequencing; xia-gibbs syndrome.