Sunday, June 29, 2008

Relationship between lymphoscintigraphy and clinical findings in lower limb lymphedema (LO): toward a comprehensive staging.

Relationship between lymphoscintigraphy and clinical findings in lower limb lymphedema (LO): toward a comprehensive staging.
Lymphology. 2008 Mar

Pecking AP, Albérini JL, Wartski M, Edeline V, Cluzan RV.
Department of Nuclear Medicine, Centre René Huguenin, Saint-Cloud, France.

Although radionuclide lymphoscintigraphy (RNL) is widely used diagnostically for patients with lymphedema (LE), it has not been utilized for LE staging, which is still based upon clinical findings. The aim of this work is to establish whether the results of both conventional RNL and fusion imaging obtained from hybrid detectors may be used for a comprehensive clinicoimaging staging in LE. Radiolabeled nanocolloids (0.2 ml) were subcutaneously injected in 4,328 patients (23-78 years) with clinical lower limb LE and without venous disease. Patients were classified according to the ISL classification and had a minimal follow-up of 2 years. Images were taken 60 minutes after the injection as a whole body scanning and fusion images of functional SPET and anatomical CT. Clinical and RNL results were not in accordance, and a specific RNL staging was established. The association of clinical and functional staging yields a new method to grade LE patients, and this staging correlated with treatment efficacy. RNL is an important tool in lymphology, and its association with the clinical evaluation offers a new grading system which may be able to delineate patients with good prognosis, patients at risk for a complex decongestive physiotherapy (CDP) failure, and patients who may benefit from other therapeutic protocols.


Friday, June 27, 2008

Candidate gene analysis in primary lymphedema

Candidate gene analysis in primary lymphedema
Lymphat Res Biol. 2008

Ferrell RE, Kimak MA, Lawrence EC, Finegold DN.
University of Pittsburgh, Department of Human Genetics, Pittsburgh, Pennsylvania.

Abstract Background: Primary lymphedema, the accumulation of protein-rich fluid in the interstitial space, is the clinical manifestation of mutations involved in lymphatic development and function. Mutations in three genes, VEGFR3, FOXC2, and SOX18, cause primary lymphedema. However, mutations in these three genes only account for a fraction of primary lymphedema. To identify other genes mutated in primary lymphedema, we resequenced twenty-five biologically plausible candidate genes for lymphedema in a large collection of primary lymphedema families.

Methods and Results: Candidate genes were selected on the basis of gene expression in lymphatic endothelial cells, differential antigenic expression in lymphatics, and mouse studies of lymphatic development. The gene sequence was downloaded from GenBank and sequence primers designed to amplify 1 Kb of the 5' sequence, exons and flanking intron-exon boundaries, and 500 bp of the UTR of each gene. No common causative mutations were observed among the 25 genes screened.

Single mutations were observed in elastin microfibril interfacer (EMILIN1), lymphocyte cytosolic protein 2 (LCP2), fatty acid binding protein 4 (FABP4), protein tyrosine kinase SYK (SYK), neuropilin-2 (NRP2), SpSRY-box 17 (SOX17), vascular cell adhesion molecule 1 (VCAM1), ROR orphan receptor C (RORC), and vascular endothelial growth factor B (VEGFB). Among these, the mutations in EMILIN1, RORC, LCP2, SYK, and VEGFB failed to segregate with lymphedema. The mutations in FABP4 (2), NRP2, SOX17, and VACM1 are consistent with being causative mutations, but occur in families too small to convincingly confirm cosegregation of mutation and phenotype.

Conclusion: We excluded mutation in 21 biological candidate genes as a common cause of primary lymphedema. Mutations in FABP4, NRP2, SOX17 and VCAM1 are consistent with causality and follow up of these four genes are warranted. The evidence for FABP4 harboring lymphedema mutations is discussed.

Mary Ann Liebert

HGF and MET Mutations in Primary and Secondary Lymphedema.

HGF and MET Mutations in Primary and Secondary Lymphedema.

Lymphat Res Biol. 2008

inegold DN,
Schacht V, Kimak MA, Lawrence EC, Foeldi E, Karlsson JM, Baty CJ, Ferrell RE.
Department of Human Genetics, University of Pittsburgh, Pittsburgh, Pennsylvania., Department of Pediatrics, University of Pittsburgh, Pittsburgh, Pennsylvania., DNF, CJB, and REF contributed equally to this work.

Abstract Background: Lymphedema is the abnormal accumulation of protein-rich fluid in the interstitial space. Primary lymphedema is a rare genetic condition with both autosomal dominant and autosomal recessive modes of inheritance.

Three genes, FLT4
VEGFR3), FOXC2, and SOX18 cause varying forms of primary lymphedema. In industrialized countries, secondary lymphedema is usually associated with cancer therapy and/or trauma. Recent observations suggested that hepatocyte growth factor/high affinity hepatocyte growth factor receptor (HGF/MET) were new candidate lymphedema genes.

Methods and Results: The coding exons and flanking regions of HGF and MET were directly sequenced in 145 lymphedema probands, 59 unrelated women with secondary lymphedema following treatment for
breast cancer, 21 individual patients with lymphedema and intestinal lymphangiectasia, and at least 159 unrelated ethnic matched control individuals. Mutations leading to truncation or missense changes in evolutionarily conserved residues of HGF and MET were identified. These mutations were not polymorphic in control individuals.

Conclusions:The identification of HGF/MET mutations in primary lymphedema, lymphedema/lymphangiectasia, and breast cancer-associated secondary lymphedema suggests that the HGF/MET pathway is causal or alters susceptibility for a broad range of lymphedema phenotypes. The HGF/MET pathway provides a new target for the prevention and/or
treatment of lymphedema.

Mary Ann Liebert

Tuesday, June 10, 2008

Estimating the population burden of lymphedema

Estimating the population burden of lymphedema

Ann N Y Acad Sci. 2008 May

Rockson SG, Rivera KK.
Stanford Center for Lymphatic and Venous Disorders, Division of Cardiovascular Medicine, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA 94305.

Lymphedema is a complex, regional edematous state that ensues when lymph transport is insufficient to maintain tissue homeostasis. The disorder is remarkably prevalent, but the population implications of lymphatic dysfunction are not well-studied. Prevalence estimates for lymphedema are relatively high, yet its prevalence is likely underestimated. The ability to estimate the burden of disease poses profound implications for current and future lymphedema patients, but the challenge to correctly surmise the incidence and prevalence of lymphedema is complex and the relevant medical literature is scanty. In the absence of the highly desired, prospectively designed and rigorously performed relevant epidemiologic studies, it is instructive to look at the existing studies of lymphedema disease burden. In the current review, the extant literature is examined in the context of the disease setting in which tissue edema is encountered. Incidence or prevalence estimates are provided or inferred, and, where feasible, the size of the subject population is also identified. It is extremely attractive to contemplate that future approaches will entail formal, prospectively designed studies to objectively quantitate incidence and prevalence statistics for individual categories, as well as for the global lymphedema population prevalence.

Annals of the New York Academy of Sciences