Giant umbilical cord and hypoglycemia in an infant with Proteus syndrome.

Proteus syndrome (PS) is characterized by the progressive, segmental, or patchy overgrowth of the skin, and other tissues. This is the first case report of recurrent severe insulin-independent hypoglycemia in an infant with PS. Somatic p.E17K of AKT1 mutation was confirmed. The patient also had a giant umbilical cord, which has not yet been reported in PS.

Characterization of thrombosis in patients with Proteus syndrome.

Patients with overgrowth and complex vascular malformation syndromes, including Proteus syndrome have an increased risk of thromboembolism. Proteus syndrome is a mosaic, progressive overgrowth disorder involving vasculature, skin, and skeleton, and caused by a somatic activating mutation in AKT1. We conducted a comprehensive review of the medical histories and hematologic evaluations of 57 patients with Proteus syndrome to identify potential risk factors for thrombosis. We found that six of ten patients, who were deceased, died secondary to deep venous thrombosis and/or pulmonary embolism. Of the remaining 47 living patients, six had thromboembolic events that all occurred postoperatively and in an affected limb. Eleven of 21 patients had an abnormal hypercoagulable panel including Factor V Leiden heterozygotes, antithrombin III deficiency, positive lupus anticoagulant, or Protein C or S deficiencies. We observed that eight of 17 patients had an abnormal D-dimer level >0.5 mcg/dl, but deep venous thromboses occurred in only four of those with D-dimer >1.0 mcg/dl. We conclude that the predisposition to thrombosis is likely to be multifaceted with risk factors including vascular malformations, immobility, surgery, additional prothrombotic factors, and possible pathophysiologic effects of the somatic AKT1 mutation on platelet function or the vascular endothelium. The D-dimer test is useful as a screen for thromboembolism, although the screening threshold may need to be adjusted for patients with this disorder. We propose developing a registry to collect D-dimer and outcome data to facilitate adjustment of the D-dimer threshold for Proteus syndrome and related disorders, including PIK3CA-Related Overgrowth Spectrum.

Proteus syndrome and immunodeficiency.

A 10 year old boy with Proteus syndrome presented with a pericardial effusion of unknown aetiology. Immunological investigation revealed low serum IgG and IgA, accompanied by low levels of specific antibodies to pneumococcal and haemophilus type B polysaccharides. Circulating lymphocyte surface marker profile revealed T and B cell lymphopenia. This is the first report of hypogammaglobulinaemia occurring in the Proteus syndrome.

Growth hormone (GH), insulin-like growth factors (IGFs), and IGF-binding protein-3 (IGFBP-3) in a child with Proteus syndrome.

Proteus syndrome is a congenital hamartomatous disorder characterized by partial overgrowth involving all germ layers. A somatic mutation model has been proposed since familial cases are extremely rare. We report on a 3-year-old girl with typical manifestations of Proteus syndrome, including local, asymmetric hypertrophy of various parts of the body. Total body length was reduced. Serum levels of IGF-I and especially IGF-II and their major growth hormone dependent binding protein (IGFBP-3) were significantly reduced, although growth hormone secretion after a pharmacological stimulus was normal. In vitro studies of fibroblasts derived from hypertrophied tissue showed normal IGF-I production and somewhat reduced IGF-II and IGFBP-3 production as compared to normal human skin fibroblasts. Affinity cross-linking experiments showed that fibroblasts of the affect tissue in Proteus syndrome produced an unusual pattern of IGF bindings proteins containing large amounts of an IGFBP with high affinity to IGF-II. The data suggest that IGF production is generally disturbed in Proteus syndrome with imbalanced levels of specific IGFBP in affected tissue.