Early identification of LPIN1 variant in a child with severe myoglobinuria and a history of sibling deaths.

Rhabdomyolysis in children is frequently attributed to viral myositis or trauma; however, severe or recurrent episodes precipitated by febrile illnesses often indicate an underlying genetic myopathy. Variants in the LPIN1 gene, which encodes the phosphatidic acid phosphatase Lipin-1, have recently emerged as a major cause of early-onset, life-threatening rhabdomyolysis (Autosomal Recessive Acute Recurrent Myoglobinuria). We present the case of a 5-year-old female who presented with acute onset profound lethargy, generalized muscle weakness, and cola-colored urine following a viral prodrome, on a background of previous similar milder episodes. The patient's family history was significant for consanguinity and the unexplained deaths of two siblings at similar ages. Laboratory investigations revealed massive rhabdomyolysis with a creatine phosphokinase (CPK) level of 59,679 U/L and significant myoglobinuria, though renal function remained initially preserved. Given the severity of the presentation and family history, comprehensive genetic investigation was pursued. Whole Exome Sequencing (WES) of a similarly affected younger sibling, followed by targeted familial screening, identified a homozygous variant in the LPIN1 gene; NM_001349206.2: c.2360_2361delinsGA p.(Pro787Arg) in our patient. The patient was managed conservatively with vigorous hydration and alkalinization of urine, resulting in clinical improvement without the development of acute renal failure. LPIN1 deficiency is a critical differential diagnosis in pediatric patients presenting with unexplained, massive rhabdomyolysis, particularly in the context of consanguinity or a history of sibling mortality preceded by muscle weakness. This case highlights the utility of Whole Exome Sequencing post-stabilization to establish a strong molecular basis for the diagnosis, which terminates the diagnostic odyssey and is essential for providing genetic counseling to affected families.