Pseudoxanthoma Elasticum–like Syndrome
A 27-year-old man was referred to the hematology clinic for evaluation of abnormal coagulation laboratory studies. He had no history of liver disease, malabsorptive conditions, or easy bleeding, but he reported having had sagging skin since adolescence. He reported that his sister had similar skin findings and coagulation test results. On physical examination, there were loose skinfolds across the torso and in the axillae. Laboratory studies showed prolonged prothrombin and activated partial-thromboplastin times and decreased activity levels of the vitamin K–dependent coagulation factors. The patient was referred for genetic testing owing to concern about an inherited condition. Molecular analyses were negative for the genetic variant that causes pseudoxanthoma elasticum — a condition in which mineralization and fragmentation of elastic fibers lead to lax, redundant skin — as well as for the separate genetic variant that causes congenital deficiency of vitamin K–dependent coagulation factors. However, a pathogenic variant in the gene coding for γ-glutamyl carboxylase, a crucial enzyme for vitamin K metabolism, was identified and explained the skin and coagulation-test abnormalities. A diagnosis of pseudoxanthoma elasticum–like syndrome with multiple coagulation-factor deficiency was made. Owing to the absence of hematologic symptoms, the patient’s treatment was managed expectantly, with a plan to administer prothrombin-complex concentrate if bleeding occurred in the future.