Congenital generalized lipodystrophy type 4 due to a novel PTRF/CAVIN1 pathogenic variant in a child: effects of metreleptin substitution

Objectives: Congenital generalized lipodystrophies (CGLs) are a heterogeneous group of rare autosomal recessive disorders characterized by near/total absence of body fat. Pathogenic variants in polymerase-I and transcript release factor gene (PTRF), or CAVIN1, is responsible for CGL4. In addition to generalized fat loss, patients with CGL4 were reported to suffer from myopathy, malignant cardiac arrhythmias, gastrointestinal disorders, and skeletal abnormalities. Here we describe the phenotype of a child with CGL4 due to a rare, novel pathogenic variant in the PTRF/CAVIN1 gene and the long-term effects of metreleptin substitution on comorbidities.

Case presentation: We describe a now 20-year-old female patient. At the age of 14-years, she was referred to the University Clinic because of uncontrolled diabetes with an HbA1c of 9.3%, requiring 2.4 IU insulin/kg total-body-weight to normalize blood glucose, hepatomegaly, and hypertriglyceridemia of 515 mg/dL. Additionally, she was suffering from malignant cardiac arrhythmia, myopathy, and hyperCKemia. In light of these clinical findings, she was diagnosed with CGL due to a rare, novel variant in the PTRF gene, and was started on metreleptin, a synthetic analog of human leptin. After the initiation of metreleptin treatment, insulin therapy could be stopped and improvement of sonographically assessed liver size was observed, even though serum liver function test stayed mildly elevated. Furthermore, a noticeable improvement of the serum triglyceride levels was also seen. Medical care and regular follow-up visits are being carried out by a multi-disciplinary team.

Conclusions: Although CGL4 is rare, due to its life-threatening comorbidities and the opportunity for an early intervention, it is important that the clinicians should recognise these patients.