SHOX Deficiency in Argentinean Cohort: Long-Term Auxological Follow-Up and a Family's New Mutation

Novel heterozygous mutation in the SHOX gene leading to familial idiopathic short stature: A case report and literature review

BACKGROUND

The pathogenic mutation of short stature homeobox (SHOX) gene is one of the main genetic causes of short stature in children, with an incidence rate of 1/1000~1/2000 and the main clinical manifestations are short stature and (or) limb skeletal abnormalities. SHOX gene mutations are mostly large deletions of regulatory sequence genes, while exon mutations are relatively rare. The pathogenic rate of mutations occurring in exon 5 is only 1/50 000~1/100 000. This study reviewed the clinical data of a child with SHOX gene mutation in exon 5, and analyzed the clinical phenotype, pathogenesis, diagnosis, treatment and prognosis of SHOX gene mutation in combination with relevant literature at home and abroad.

CASE PRESENTATION

The patient was an 8-year-old girl with a height of 105.2 cm (-4.31 standard deviations). Her sitting height/height ratio was 56.8% (>55.5%), and she exhibited high-arched palate, irregular dentition, micrognathia, short fingers, and a normal growth hormone stimulation test. Whole-exome sequencing was performed, and Sanger sequencing was used for site validation. The sequencing results revealed a heterozygous mutation of c.577G > A in exon 5 of the SHOX gene, inherited from the father. The clinical symptoms of the proband were consistent with the phenotype of short stature idiopathic familial associated with SHOX gene mutations. The father, grandfather, uncle, and sister of the proband all had the c.577G > A heterozygous mutation. Therefore, the clinical diagnosis was childhood short stature caused by SHOX gene defects. The SHOX: c.577G > A mutation is likely to be the genetic etiology of familial idiopathic short stature in this family, and this novel mutation enriches the mutation spectrum of the SHOX gene.

CONCLUSION

This is the first case report of familial idiopathic dwarfism caused by mutation at the c.577G > A locus of exon 5 of SHOX gene in the world. This novel mutation enriches the mutation spectrum of the SHOX gene. It is important to emphasize genetic testing, including the SHOX gene, in patients with familial idiopathic short stature and to provide timely growth hormone therapy to individuals with short stature caused by SHOX gene mutations in order to improve their adult height.

Skeletal dysplasias in Latin America

Skeletal dysplasias (SD) are disturbances in growth due to defects intrinsic to the bone and/or cartilage, usually affecting multiple bones and having a progressive character. In this article, we review the state of clinical and research SD resources available in Latin America, including three specific countries (Brazil, Argentina, and Chile), that have established multidisciplinary clinics for the care of these patients. From the epidemiological point of view, the SD prevalence of 3.2 per 10,000 births from nine South American countries included in the ECLAMC network represents the most accurate estimate not just in Latin America, but worldwide. In Brazil, there are currently five groups focused on SD. The data from one of these groups including the website www.ocd.med.br, created to assist in the diagnosis of SD, are highlighted showing that telemedicine for this purpose represents a good strategy for the region. The experience of more than 30 years of the SD multidisciplinary clinic in an Argentinian Hospital is presented, evidencing a solid experience mainly in the follow-up of the most frequent SD, especially those belonging the FGFR3 group and OI. In Chile, a group with 20 years of experience presents its work with geneticists and pediatricians, focusing on diagnostic purposes and clinical management. Altogether, although SD health-care and research activities in Latin America are in their early stages, the experience in these three countries seems promising and stimulating for the region as a whole.