Nail-Patella Syndrome Presenting with Nephrotic Syndrome during Pregnancy

Introduction: We report a rare cause of nephrotic syndrome. Case Description: A 38-year-old woman with a one-year history of proteinuria, hypoalbuminemia and new headache and blurred vision presented to our clinic at 9 weeks of pregnancy. Physical examination: normotensive, lower limbs edema, Marcus Gunn's sign on right eye, bilateral optic disc edema and serous exudative retinal detachment. Lumbar puncture showed inflammatory CSF. Neoplastic, infectious and systemic autoimmune causes were excluded. A diagnosis of Vogt-Koyanagi-Harada was made and received steroids and azathioprine. Visual acuity slightly improved. She presented with nephrotic syndrome resistant to prednisone, with proteinuria of 8 g/24 hrs., serum albumin 2 g/dl, hypercholesterolemia, Cr 0.3 mg/dl. Renal biopsy revealed non-specific glomerular changes and EM revealed diffuse FPE and myeloid bodies (MBs). GLA enzymatic activity was normal and GLA sequencing was negative. Exomic sequencing identified a heterozygous pathogenic variant in LMX1B. She delivered a healthy baby boy at term. One year after birth: Cr 0.4 mg/dl, serum albumin 4 g/dl and proteinuria 2.6 g/24 hrs. We studied her 22-year-old daughter and found the same variant. She did not show patellar abnormalities but had nail dysplasia. Discussion: MBs are classically associated but not exclusive of Fabry Disease. The patient had no exposure to silica or drugs. NPS is an autosomal-dominant disease with variable penetrance caused by mutations in LMX1B. Our patient presented with patellar hypoplasia, triangular lunulae, reduced sensation to pain and temperature in hands and feet and renal involvement. The risk of preeclampsia in NPS is increased and onset of nephrotic syndrome during pregnancy has been described. This case illustrates the difficulties of diagnosing rare kidney diseases with subtle clinical hints and the importance of EM and sequencing technologies to reach a definitive diagnosis. It is one of the few cases described of NPS and pregnancy.EM shows MBs in podocytes