Introduction Biologically active forms of riboflavin, which is an important factor in myelin synthesis, are important cofactors of carbohydrate, amino acid, and lipid metabolism. The mutations in the riboflavin transporter genes (SLC52A2, SLC52A3) cause riboflavin transporter deficiency (Brown-Vialetto-Van Laere syndrome, BVVLS). BVVLS is a rare neurodegenerative disease that can be treated. Herein, a premature infant, who has signs of hypotonia and right diaphragmatic eventration, and pre-diagnosed spinal muscular atrophy with respiratory distress (SMARD) syndrome, however; patient’s genetic analysis revealed autosomal recessively inherited riboflavin transporter deficiency, is presented.

Case A girl infant, referred to our unit at the second day, was born 2400 g at 33^rd week from a consanguineous marriage. Apgar score was 5/7 at 1^st and 5^th minute and she was intubated due to irregular respiration and hypotonia. The history of the patient revealed that the pregnancy was normal and her first brother diagnosed with hypotonic infant and died when he was six months old. Physical examination showed paradoxical respiration, severe hypotonia, decreased deep-tendon reflexes, generalised muscle weakness. Right diaphragmatic eventration was shown on her chest x-ray. Biochemical evaluations, creatine kinase, blood gas, lactate, pyruvate, ammonia, urine-blood amino acids and urine organic acid analysis were normal. Tandem-MS revealed high levels of C5 and C6. SMN1 gene deletion was not detected, so, diagnosis of SMA was excluded. Auditory brainstem response test was normal. The patient was considered as SMARD due to hypotonia and diaphragmatic eventration. A neuromuscular panel which screens 443 neuromuscular disease genes was tested for genetic diagnosis. The patient was extubated when she was 80 days old. She was discharged with enteral tube feeding when she was 110 days old. The patient was diagnosed with BVVLS with mutations in the SLC52A2 gene (c.-110–1G> A, c.297G> C). Oral riboflavin was initiated at the dose of 10–40 mg/kg/day to the patient. Spontaneous movements in the patient’s lower limbs started and swallowing dysfunction regressed with the therapy of riboflavin. She is still under clinical following-up.

Conclusion If it could not be diagnosed in hypotonic infants performed to primary investigations, molecular genetic analyses should be kept in mind to diagnosis for rare neuromuscular diseases such as riboflavin transporter deficiency.