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Li-Fraumeni Syndrome Synonyms, Key Words, and Related Terms: Li-Fraumeni syndrome, LFS, LFL kindred, p53 mutation, Li-Fraumeni僕ike kindred, germline mutation, p53 tumor suppressor gene mutation, TP53, TP53 tumor suppressor gene mutation, breast cancer, brain tumor, acute leukemia, soft tissue sarcoma, osteosarcoma, adrenal cortical carcinoma |
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| AUTHOR INFORMATION | Section 1 of 10 |
Authored by Kavita Patel, MD, Department of Pediatrics, University of California at Los Angeles, Mattel Children痴 Hospital
Coauthored by Kathleen Sakamoto, MD, Professor, Department of Pediatrics, Division of Hematology-Oncology and Pathology and Laboratory Medicine, Mattel Children's Hospital, David Geffen School of Medicine, University of California at Los Angeles; Gary R Jones, MD, Associate Medical Director, Clinical Development, Berlex Laboratories
Kavita Patel, MD, is a member of the following medical societies: American Academy of Pediatrics, American Medical Association, Phi Beta Kappa, and Texas Medical Association
Edited by Stephan A Grupp, MD, PhD, Director, Stem Cell Biology Program, Children's Hospital of Philadelphia; Assistant Professor, Department of Pediatrics, Division of Oncology, University of Pennsylvania; Mary L Windle, PharmD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy, Pharmacy Editor, eMedicine.com, Inc; Timothy P Cripe, MD, PhD, Associate Professor of Pediatric Hematology/Oncology, University of Cincinnati; Director, Translational Research Trials Office, Department of Pediatrics, Cincinnati Children's Hospital Medical Center; Samuel Gross, MD, Professor Emeritus, Department of Pediatrics, University of Florida, Clinical Professor, Department of Pediatrics, UNC, Adjunct Professor, Department of Pediatrics, Duke University; and Max J Coppes, MD, PhD, MBA, Executive Director, Center for Cancer and Blood Disorders, Children's National Medical Center
| Author's Email: | Kavita Patel, MD | |
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| Editor's Email: | Stephan A Grupp, MD, PhD |
eMedicine Journal, July 12 2006, VOLUME 7,
Number 7
| INTRODUCTION | Section 2 of 10 |
Background: Li-Fraumeni syndrome (LFS) is a rare autosomal dominant syndrome in which patients are predisposed to cancer. LFS is characterized by the wide variety of cancer types seen in affected individuals, a young age at onset of malignancies, and the potential for multiple primary sites of cancer during the lifetime of affected individuals. The following 3 criteria must be met for a diagnosis of LFS:
Most hereditary family cancer syndromes involve 1 or 2 specific tumor types, whereas members of LFS kindreds are at risk for a wide range of malignancies, with particularly high occurrences of breast cancer, brain tumors, acute leukemia, soft tissue sarcomas, bone sarcomas, and adrenal cortical carcinoma. Several other cancers have been seen at lower rates in LFS kindreds. Although osteosarcoma and chondrosarcomas occur frequently, no evidence exists of increased occurrence of Ewing sarcoma in association with LFS. Since LFS was first characterized in 1969, more than 100 LFS kindreds have been described.
Pathophysiology: LFS has been linked to germline mutations of the tumor suppressor gene p53 (TP53). Mutations can be inherited or can arise de novo early in embryogenesis or in one of the parent's germ cells. Involvement of TP53 mutations was reported first in 1990 by Malkin et al. Subsequent studies analyzing the coding and noncoding portions of TP53 have shown that approximately 70% of LFS kindreds have constitutional (germline) mutations of 1 of the 2 copies of the TP53 tumor suppressor gene; the second copy is normal. TP53, which is located on chromosome band 17p13, codes for a 53-kd nuclear protein transcription factor that has important regulatory control over cell proliferation and homeostasis, specifically the cell cycle, DNA repair processes, and apoptosis.
Somatic (nongermline) TP53 tumor suppressor gene mutations are common in sporadic human cancers, suggesting that TP53 alterations play an important role in the development of cancer. Moreover, a broad range of cell line and transgenic animal experiments show direct involvement of TP53 mutations in malignant transformation. Alterations of p53 function are the result of either loss of function of wild type p53, increased or aberrant protein function, or dominant negative effects of the mutated protein. This impairment in p53 function is thought to lead to loss of protection against the accumulation of genetic alterations.
These laboratory data support the hypothesis of constitutional mutations as the etiology of LFS. Although inactivation of TP53 confers a predisposition to cancer, this alone is not sufficient because not all families with classic LFS have detectable alterations of TP53. This could be a result of how TP53 alterations are assessed. Previous analyses only measured certain portions of the gene. In addition, the p53 protein may undergo posttranslational alterations. Finally, LFS can result from defects in other genes that participate in the cell cycle regulatory pathway.
Specifics of the inherited TP53 mutation may have a significant effect on the cancer phenotype in the affected family. Most LFS-associated TP53 defects involve missense point mutations occurring in a hot-spot region of exons 5-8, a portion of the gene coding for the core DNA-binding domain of the protein. Missense mutations lead to a stable but inactive protein, which accumulates in the nucleus of tumor cells. Frameshift, nonsense, and splice site mutations can also be present; these do not lead to accumulation of p53 protein.
Kindreds with constitutional mutations in the hot spot region display more aggressive cancer phenotypes than patients with other TP53 mutations, and those patients that appear to lack any heritable defect. Families with mutations in the hot spot region include those with younger probands at the time of cancer diagnosis. Mutations in exons 5-8 are also associated with a higher overall incidence in family members with breast cancer and CNS tumors diagnosed when patients are younger than 45 years, suggesting a higher rate of penetrance of the cancer phenotype in families with these types of inherited TP53 defects.
A significant portion of LFS and, particularly, Li-Fraumeni僕ike (LFL) kindreds do not have demonstrable constitutional TP53 mutations. This suggests that other mechanisms disrupting normal function or defects in other genes may also be involved in familial predisposition to a variety of cancer types. A small percentage of LFS and LFL kindreds without evidence for TP53 germline mutations have been shown to have germline mutations of the checkpoint kinase gene CHK2 localized to chromosome band 22q12. CHK2 kinase activates p53 after DNA damage. CHK2 is associated with increased incidence of certain types of cancers (like breast cancer) within the LFS/LFL kindreds.
Frequency:
Mortality/Morbidity: The cancers that occur most commonly in members of LFS kindreds are breast cancer, brain tumors, acute leukemia, soft tissue sarcomas, osteosarcoma, and adrenal cortical carcinoma. A significant proportion of affected patients, particularly children, can be treated successfully for the initial cancer but are at significant risk of subsequent development of a second primary malignancy.
Race: No evidence exists of either an ethnic predisposition for LFS or an increased or decreased frequency based on nationality.
Sex:
Age: While approximately 10% of cancers occur in individuals younger than 45 years in the general population, more than one half of the cancers occur in LFS family members younger than 45 years, even when members who meet clinical criteria for LFS are excluded.
| CLINICAL | Section 3 of 10 |
History:
Physical:
Causes:
| DIFFERENTIALS | Section 4 of 10 |
Acute Lymphoblastic Leukemia
Acute Myelocytic Leukemia
Adrenal Carcinoma
Astrocytoma
Bioethics in Pediatric Practice
Childhood Cancer, Epidemiology
Childhood Cancer, Genetics
Chromosomal Breakage Syndromes
Gardner Syndrome and Other Intestinal Polyposis Syndromes
Late Effects of Childhood Cancer and Treatment
Nonrhabdomyosarcoma Soft Tissue Sarcomas
Osteosarcoma
Retinoblastoma
Rhabdomyosarcoma
WAGR Syndrome
Wilms Tumor
Other Problems to be Considered:
Families with LFL syndrome have (1) a proband younger than 45 years with childhood cancer or sarcoma, brain tumor, or adrenal cortical carcinoma, (2) first- or second-degree relative with a typical LFS cancer occurring at any age, and (3) another first- or second-degree relative in the lineage younger than 60 years diagnosed with any cancer. Only approximately 20% of LFL kindreds have demonstrable germline TP53 mutations. Much less stringent criteria for LFL familial cancer predisposition include 2 first- or second-degree relatives with LFS-related malignancies (sarcoma, breast cancer, malignant brain tumor, adrenal cortical carcinoma, acute leukemia) at any age.
Breast and ovarian cancer family syndrome with genetic mutations of BRCA1 or BRCA2 may be in the differential diagnosis.
| WORKUP | Section 5 of 10 |
Lab Studies:
Imaging Studies:
| TREATMENT | Section 6 of 10 |
Medical Care:
Surgical Care: Prophylactic mastectomy is controversial in the LFS population and is not advocated as a reasonable surgical intervention.
Consultations: Strongly consider genetic counseling for families with LFS to ensure appropriate understanding of potential risk and possible evaluation of genetic predisposition markers.
| FOLLOW-UP | Section 7 of 10 |
Further Outpatient Care:
Deterrence/Prevention:
Prognosis:
Patient Education:
| MISCELLANEOUS | Section 8 of 10 |
Medical/Legal Pitfalls:
| TEST QUESTIONS | Section 9 of 10 |
CME Question 1: Family members with Li-Fraumeni syndrome have a significant predilection for which of the following cancers?
A: Melanoma, mouth and throat carcinoma, and thyroid cancer
B: Colorectal, lung, kidney, and pancreatic cancers
C: Breast cancer, brain cancer, acute leukemia, and soft tissue sarcoma
D: Retinoblastoma and osteosarcoma
E: Breast and ovarian cancers
The correct answer is C: Although a variety of cancers can be seen in Li-Fraumeni syndrome kindreds, by definition, the proband has sarcoma. The syndrome was described originally in families of patients with rhabdomyosarcoma. Breast cancer, brain tumors, acute leukemia, osteosarcoma, and adrenal cortical carcinoma also occur very commonly in affected families.
CME Question 2: Which of the following kindreds meets the clinical criteria for diagnosis of classic Li-Fraumeni syndrome?
A: 4-year-old boy with acute lymphocytic leukemia, maternal grandfather aged 41 years with brain tumor, and paternal grandmother aged 35 years with breast cancer
B: 27-year-old woman with breast cancer, mother with breast cancer diagnosed at age 55 years, and maternal grandmother with breast cancer diagnosed at age 48 years
C: 18-month-old girl with adrenal cortical carcinoma and mother with breast cancer diagnosed at age 32 years
D: 6-year-old boy with embryonal rhabdomyosarcoma, mother with breast cancer diagnosed at age 34 years, and maternal uncle with colon cancer diagnosed at age 42 years
E: 16-year-old girl with acute myelogenous leukemia and a history of successfully treated Ewing sarcoma, paternal grandfather with brain tumor diagnosed at age 32 years, and paternal second cousin diagnosed with breast cancer at age 40 years
The correct answer is D: Minimum criteria for Li-Fraumeni syndrome require a proband with sarcoma diagnosed at younger than 45 years, a first-degree relative with cancer also diagnosed at younger than 45 years, and a first- or second-degree relative from the same genetic lineage diagnosed with cancer at younger than 45 years or sarcoma diagnosed at any age. Only the kindred represented in answer D meets these criteria.
Pearl Question 1 (T/F): The most common genetic mutation associated with Li-Fraumeni syndrome is a constitutional (ie, germline) mutation of the gene coding for the p53 protein.
The correct answer is True: Approximately 70% of Li-Fraumeni syndrome kindreds have a germline mutation of the gene coding for p53.
Pearl Question 2 (T/F): A child in a kindred with a Li-Fraumeni syndrome with a documented germline mutation at the site coding for the p53 protein is diagnosed with rhabdomyosarcoma. Each of the child's full siblings has a 50% chance of also being affected by an increased predilection for cancer at an early age.
The correct answer is True: Increased cancer risk in Li-Fraumeni syndrome is inherited as an autosomal dominant trait.
Pearl Question 3 (T/F): All children with soft tissue sarcoma are at high risk of having a germline mutation at the site coding for the p53 protein (Li-Fraumeni syndrome).
The correct answer is False: Diagnosis in an infant younger than 24 months and with a family history of cancer at a young age or history of previous cancer are factors that suggest germline mutations at the site coding for the p53 protein. Of children with soft tissue sarcomas, 5-10% have family histories of malignancies consistent with Li-Fraumeni syndrome of other syndromes with an autosomal dominant inheritance pattern.
Pearl Question 4 (T/F): For children diagnosed with soft tissue sarcoma, osteosarcoma, or adrenal cortical carcinoma, only similar types of cancer at similar ages should be addressed in the family history when assessing for Li-Fraumeni syndrome.
The correct answer is False: Any type of cancer at any age should be identified in family members. This is not limited to cancers most commonly seen in Li-Fraumeni syndrome or in individuals younger than 45 years. Families that do not meet strict criteria for Li-Fraumeni syndrome may have evidence of increased cancer risk and may benefit from genetic counseling.
| BIBLIOGRAPHY | Section 10 of 10 |
| NOTE: |
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