Proteus syndrome

Signs and symptoms

Proteus syndrome causes an overgrowth of skin, bones, muscles, fatty tissues, and blood and lymphatic vessels. Proteus syndrome is a progressive condition wherein children are usually born without any obvious deformities. Tumors of skin and bone growths appear as they age typically in early childhood. The musculoskeletal manifestations are cardinal for the diagnosis of Proteus syndrome. The severity and locations of these asymmetrical growths vary greatly but typically the skull, one or more limbs, and soles of the feet will be affected. There is a risk of premature death in affected individuals due to deep vein thrombosis and pulmonary embolism caused by the vessel malformations that are associated with this disorder. Because of carrying excess weight and enlarged limbs, arthritis and muscle pain may also be symptoms. Further risks may occur due to the mass of extra tissue.

The disorder does not uniformly cause learning impairments: the distribution of intelligence deficits among those with Proteus syndrome appears higher than that of the general population. This is difficult to determine with statistical significance. In addition, the presence of visible deformity hurts the social experiences of the affected individual, causing emotional difficulties, social rejection and stigma.

Affected individuals are at increased risk for developing certain tumors including unilateral ovarian cystadenomas, testicular tumors, meningiomas, and monomorphic adenomas of the parotid gland.

Hemimegalencephaly is often found to be associated.

Orthopaedic features

The musculoskeletal manifestations of Proteus syndrome are frequent and recognizable. Patients tend to demonstrate a unique pattern of skeletal abnormalities. The orthopaedic features are usually bilateral, asymmetrical, and progressive, and involve all four limbs and the spine. Affected patients usually have localized periarticular limb distortions, limb length discrepancy, and spine deformity. Patients with Proteus syndrome can have regular bone configuration and contours despite the bone enlargement. Patients can also exhibit deformation of the skull in the form of dolichocephaly or elongated skull and facial abnormalities. Because of the rarity of the syndrome and the variability of signs, orthopaedic management should be individualized.

Genetics

In 2011 researchers determined the cause of Proteus syndrome. In 26 of 29 patients who met strict clinical criteria for the disorder, Lindhurst et al. identified an activating mutation in AKT1 kinase in a mosaic state.

Previous research had suggested the condition was linked to PTEN on chromosome 10, while other research pointed to chromosome 16. Before the findings regarding AKT1 in 2011, other researchers expressed doubt regarding the involvement of PTEN or GPC3, which codes for glypican 3 and may play a role in regulating cell division and growth regulation.

Diagnosis

Differential diagnosis

• Macrodystrophia lipomatosa
• Fibrolipomatous hamartoma
• Neurofibromatosis type 1
• Klippel–Trénaunay syndrome
• Parkes Weber syndrome
• Sotos syndrome
• Hemangiomas
• Beckwith-Wiedemann syndrome

Classification

Many sources classify Proteus syndrome as a type of nevus syndrome. The lesions appear to be distributed in a mosaic manner. It has been confirmed that the disorder is an example of genetic mosaicism.

Treatment

A team of doctors in Australia has trial-tested the drug rapamycin in the treatment of a patient said to have Proteus syndrome and have found it to be an effective remedy. However, the diagnosis of Proteus syndrome in this patient has been questioned by others.

The Arqule Corporation developed the AKT1 inhibitor ARQ 092, which is being tested by a research team in the National Human Genome Research Institute at the United States National Institutes of Health in a Phase 0 dose-finding trial. In earlier tests on tissue and cell samples obtained from patients, ARQ 092 reduced phosphorylation of AKT and downstream targets of AKT in as little as two hours. The Phase 0 trial opened in November 2015. This trial is based on in vitro data showing inhibition of AKT1 in cell lines from patients with Proteus syndrome.

Notable cases

In a 1986 article in the British Medical Journal, Michael Cohen and J.A.R. Tibbles proposed the idea that Joseph Merrick (an Englishman known as the "Elephant Man") had Proteus syndrome. However, the exact condition that Joseph Merrick had is still not known with certainty.

Mandy Sellars has been diagnosed by some doctors as having this condition. Her legs and feet have grown disproportionately since birth. However, in 2013, Sellars's case was profiled on British television in a special called Shrinking My 17 Stone Legs, in which it was determined that Sellars's condition was not, in fact, Proteus syndrome, but rather the often-misdiagnosed PIK3CA-related overgrowth spectrum, a syndrome caused by a PIK3CA gene mutation.

References

References

1. James, William. (2005). "Andrews' Diseases of the Skin: Clinical Dermatology". Saunders.
2. Freedberg, et al. (2003). ''Fitzpatrick's Dermatology in General Medicine''. (6th ed.). McGraw-Hill. {{ISBN. 0-07-138076-0.
3. (2004). "Radiologic manifestations of Proteus syndrome". Radiographics.
4. [https://news.bbc.co.uk/2/hi/uk_news/england/lancashire/6621331.stm Woman's 11-stone legs may be lost] at [[BBC]]
5. (December 1976). "Macrodactyly, hemihypertrophy, and connective tissue nevi: Report of a new syndrome and review of the literature". The Journal of Pediatrics.
6. (July 27, 2011). "Hamartoma Syndromes, Exome Sequencing, and a Protean Puzzle". The New England Journal of Medicine.
7. (1979). "A newly recognized hamartomatous syndrome". Birth Defects Orig. Artic. Ser..
8. (Oct 1, 2004). "Reassessment of the Proteus syndrome literature: application of diagnostic criteria to published cases". American Journal of Medical Genetics.
9. Bastos, Halisson. (June 2008). "Proteus syndrome associated with hemimegalencephaly and Ohtahara syndrome: Report of two cases". Seizure.
10. El-Sobky, Tamer Ahmed. (2015). "Orthopaedic manifestations of Proteus syndrome in a child with literature update". Bone Reports.
11. (Aug 18, 2011). "A mosaic activating mutation in AKT1 associated with the Proteus syndrome.". N Engl J Med.
12. (2002). "Germline mutation of the tumour suppressor PTEN in Proteus syndrome". J. Med. Genet..
13. (2003). "Proteus syndrome and somatic mosaicism of the chromosome 16". Panminerva Medica.
14. (October 2004). "Mutation analysis of the tumor suppressor PTEN and the glypican 3 (GPC3) gene in patients diagnosed with Proteus syndrome". Am. J. Med. Genet. A.
15. "Entrez Gene: GPC3 glypican 3".
16. Abdulhady, H. (11 June 2018). "Clinical and imaging features of pedal macrodystrophia lipomatosa in two children with differential diagnosis review.". Journal of Musculoskeletal Surgery and Research.
17. Friedman, JM. (11 January 2018). "Neurofibromatosis 1.". University of Washington, Seattle.
18. Sung, HM. (2015). "Clinical experience of the Klippel-Trenaunay syndrome.". Arch Plast Surg.
19. Nguyen, TA. (2015). "Imaging Pediatric Vascular Lesions.". Clin Aesthet Dermatol.
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21. (April 22, 2008). "Rapamycin treatment for a child with germline PTEN mutation". Nature Clinical Practice Oncology.
22. (November 1, 2003). "Proteus Syndrome: Misdiagnosis with PTEN Mutations". American Journal of Medical Genetics.
23. Lindhurst, Marjorie J.. (2015-12-11). "Repression of AKT signaling by ARQ 092 in cells and tissues from patients with Proteus syndrome". Scientific Reports.
24. (Oct 31, 2015). "Dose Finding Trial of ARQ 092 in Children and Adults With Proteus Syndrome". [[National Human Genome Research Institute]] (NHGRI).
25. Lindhurst, Marjorie J.. (2015). "Repression of AKT signaling by ARQ 092 in cells and tissues from patients with Proteus syndrome". Scientific Reports.
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