Hypophosphatemic rickets in an Italian multicentric cohort of 24 subjects: a clinical and molecular characterisation.

Purpose: Rickets is a rare bone disorder due to altered calcium, vitamin D, and phosphorus metabolism, caused by nutritional deficiencies or, in 13% of cases, genetic origin. Few data are available on an Italian cohort of rickets.

Methods: Twenty-four patients with confirmed low serum phosphorus levels and reduced renal tubular phosphate reabsorption were recruited from different tertiary care centres over the last 5 years.

Heterozygous variants disrupting the interaction of ERF with activated ERK1/2 cause microcephaly, developmental delay, and skeletal anomalies.

Heterozygous deleterious null alleles and specific missense variants in the DNA-binding domain of the ETS2 repressor factor (ERF) cause craniosynostosis, while the recurrent p.(Tyr89Cys) missense variant is associated with Chitayat syndrome. Exome and whole transcriptome sequencing revealed the ERF de novo in-frame indel c.