Aim Tyrosinemia type-1 (TYR-1) is a treatable inborn error of tyrosine metabolism characterized by the deficiency of fumarylacetoacetate hydrolase due to biallelic pathogenic FAH gene variants, which causes fumarylacetoacetate and succinylacetone accumulation. Besides the classical and well-known findings related to acute and chronic liver involvement; renal Fanconi syndrome and hypophosphatemic rickets are the presenting signs in some patients. As, nutritional rickets is a frequent public health problem especially in developing countries, other causes of rickets can easily be under-recognized especially, if the systemic manifestations are unremarkable. The aim of this study is to draw attention to the rickets, as it can be both a presenting symptom and a frequent complication of TYR-1.

Material and Method Thirteen patients with hypophosphatemic rickets and genetically confirmed TYR-1, who were followed-up in Çukurova University were included in this study. The clinical, laboratory and radiological findings of the patients at first admission and follow-up were reviewed.

Results Out of 40 TYR-1 patients, only 13(32%)had rickets on admission and follow-up. Although, the presenting complaints of four(10%)patients were primarily related to rickets; nine patients had hypophosphatemic rickets along with prominent liver involvement. Age at first admission was 4.38±4(min-max:0.08–20). Parental consanguinity was present 12(92%)of 13 patients. Hepatomegaly and liver dysfunction were present in all patients. Physical examination findings of rickets were as follows: 3 craniotabes(23%),10 thickened wrists(76%),3 bowed legs or knock knees(23%),3 rachitic rosary(23%). Vitamin D and serum calcium levels were within normal limits; serum phosphate levels were below reference ranges and radiological evaluation was compatible with rickets in all patients.

Conclusions Rickets is a relatively common presenting symptom or a frequent complication of tyrosinemia type-1 apart from liver findings, as confirmed in our study with an incidence of 1 for each 3 patients. We present our cases, in order to increase the awareness of pediatricians about the close relationship between TYR-1 and rickets.