Rickets in proximal renal tubular acidosis: a case series of six distinct etiologies.

OBJECTIVES: Proximal renal tubular acidosis (pRTA) is characterized by a defect in the ability of the proximal convoluted tubule to reabsorb bicarbonate. The biochemical hallmark of pRTA is hyperchloremic metabolic acidosis with a normal anion gap, accompanied by appropriate acidification of the urine (simultaneous urine pH <5.3). Isolated defects in bicarbonate transport are rare, and pRTA is more often associated with Fanconi syndrome (FS), which is characterized by urinary loss of phosphate, uric acid, glucose, amino acids, low-molecular-weight proteins, and bicarbonate. Children with pRTA may present with rickets, but pRTA is often overlooked as an underlying cause of this condition. CASE PRESENTATION: We report six children with rickets and short stature due to pRTA. One case was idiopathic, while the remaining five had a specific underlying condition: Fanconi-Bickel syndrome, Dent's disease, nephropathic cystinosis, type 1 tyrosinemia, and sodium-bicarbonate cotransporter 1-A (NBC1-A) defect. CONCLUSIONS: Five of these six children had features of FS, while the one with NBC1-A defect had isolated pRTA.

Aromatase deficiency in a tall man: Case report of two novel mutations and review of literature.

Aromatase (CYP19A1) is the only enzyme known to catalyse the conversion of androgen to estrogen. Aromatase deficiency occurs due to mutation in CYP19A1gene which has an autosomal recessive inheritance pattern. It leads to decrease in estrogen synthesis and delayed epiphyseal closure, eunuchoid habitus and osteopenia. We are presenting here, a 24 years old male, with history of progressive increase in height and knock knees. X-ray showed open wrist and knee epiphysis. The serum testosterone level was normal and serum estradiol level was undetectable. Semen analysis showed azoospermia. Clinical exome sequencing gave two novel mutations in CYP19A1. The first variant was a novel single nucleotide deletion of thiamine at 570th base of the cDNA (c.570delT) of CYP19A1 gene. The second variant detected was again a novel one in the same gene in Exon 5 corresponding 344th base of the cDNA (c344G>A) resulting in a missense mutation of 115th arginine to glutamine in the protein. Sanger sequencing showed that the later mutation was inherited from the father. The patient was started on oral estradiol valerate for epiphyseal closure to prevent further increase in height. Only 15 mutations have been reported in the aromatase gene in males till date, our report of these novel mutations will be an add-on to the literature.