Allelic loss in esophageal squamous cell carcinoma patients with and without family history of upper gastrointestinal tract cancer

Chromosomal regions with frequent allelic loss may point to major susceptibility genes that will assist in understanding molecular events involved in esophageal carcinogenesis. Esophageal squamous cell carcinoma samples and blood from 46 patients, including 23 patients with and 23 patients without a family history of upper gastrointestinal cancer, were screened using laser microdissected DNA and tested for loss of heterozygosity (LOH) at 18 marker loci representing 14 chromosomal regions (on 2q, 3p, 4p, 4p, 5q, 6q, 8p, 9p, 9q, 11p, 13q, 14q, 15q, and 17p) identified in an earlier genome-wide scan to have frequent LOH. Clinical/pathological and lifestyle risk factor data were also collected. For all 46 tumors combined, the lowest frequency LOH for any of the 18 markers was 37%, and 8 markers showed LOH in > or =75% of informative tumors. One marker (D13S894 on 13q) showed greater LOH in patients with a positive family history (93% versus 50%; P = 0.04), whereas two markers (D6S1027 on 6q and D9S910 on 9q) had significantly more LOH in patients with metastasis, and one marker (D4S2361 on 4p) showed significantly higher LOH in patients with a lower pathological tumor grade. No relation was seen between LOH and lifestyle risk factors. This study confirms the previously observed high frequency LOH for these 14 chromosomal regions, including a locus on 13q where LOH is more common in patients with a family history of upper gastrointestinal cancer than in those without such history, suggesting that a gene in this area may be involved in genetic susceptibility to esophageal cancer.

Structural and functional brain asymmetries in human situs inversus totalis

OBJECTIVE

To determine whether individuals with situs inversus totalis (SI), a condition in which there is a mirror-image reversal of asymmetric visceral organs, have alterations in brain asymmetries.

BACKGROUND

The human brain is asymmetric in structure and function. Although correlations between anatomic asymmetries and functional lateralization in human brain have been demonstrated, it has been difficult to further analyze them. Characterization of asymmetries of brain structure and function in SI might advance the understanding of these relationships.

METHODS

Using anatomic and functional MRI techniques, we analyzed asymmetries in the brains of three individuals with SI.

RESULTS

Two major anatomic asymmetries of the cerebral hemispheres, the frontal and occipital petalia, were reversed in individuals with SI. In contrast, SI subjects had left cerebral hemisphere language dominance on functional MRI analysis as well as strong right-handedness.

CONCLUSION

These observations suggest that the developmental factors determining anatomic asymmetry of the cerebral petalia and viscera are distinct from those producing the functional lateralization of language.

Deletion analysis of the adenomatous polyposis coli and PTCH gene loci in patients with sporadic and nevoid basal cell carcinoma syndrome-associated medulloblastoma

BACKGROUND

Medulloblastomas can occur sporadically or may be associated with hereditary tumor syndromes including familial adenomatous polyposis (FAP) and nevoid basal cell carcinoma syndrome (NBCCS).

METHODS

The authors performed a retrospective analysis for allelic deletion of the adenomatous polyposis coli (APC) and PTCH gene loci using paraffin embedded medulloblastoma specimens from patients who were admitted to Children's National Medical Center in Washington, DC, between 1982 and 1997. Thirty-five cases from which tumor and normal tissue could be procured were analyzed. Two of the analyzed cases had a positive family and personal history for NBCCS; in both cases the histology of the medulloblastoma revealed a desmoplastic phenotype. Thirty-three cases were not known to be associated with hereditary disease; 2 of those cases revealed desmoplastic and 31 cases revealed nondesmoplastic "classic" medulloblastoma histology.

RESULTS

Although medulloblastoma tumorigenesis has been associated strongly with FAP associated with APC germline mutation, none of the 22 informative sporadic cases revealed loss of heterozygosity of the APC gene locus. PTCH gene deletion was detected in the tumors of both patients with NBCCS. In contrast, only 1 of 33 sporadic medulloblastomas revealed PTCH gene deletion. The sporadic case with PTCH gene deletion did not demonstrate the desmoplastic phenotype.

CONCLUSIONS

In conjunction with previous studies, the data from the current study confirm that allelic deletion occurs in NBCCS-associated medulloblastomas, consistent with the role of PTCH as a tumor suppressor gene. However, in sporadic medulloblastomas, allelic deletion of PTCH is an infrequent event. Morphologic examination in conjunction with genetic analysis of PTCH gene deletion in medulloblastoma tissue may prove to be a quick and efficient test with which to screen for NBCCS in patients with medulloblastomas. Although medulloblastoma is a component of Turcot syndrome with demonstrated APC mutations, APC gene deletions appear to be absent or very uncommon in patients with sporadic and NBCCS-associated medulloblastomas.

Mutation testing in melanoma families: INK4A, CDK4 and INK4D

The INK4A gene which codes for the cyclin-dependent kinase (CDK) inhibitor INK4A or p16 underlies susceptibility to melanoma in some families. Germline mutations in the gene that codes for the target protein of p16, CDK4, underlie susceptibility in very rare families. We report mutation screening of the INK4A and CDK4 genes in 42 UK families. A total of nine families were identified with INK4A mutations and none with CDK4 exon 2 mutations. These mutations were in 8/22 (35%) families with three or more cases of melanoma and 1/20 (5%) families with only two cases. In one of these nine families a novel single base pair substitution was identified, Gly67Arg. In an attempt to identify another melanoma susceptibility gene, a member of the INK4 family, the p19 INK4D gene has been studied. The p19 gene was sequenced in DNA from the 42 UK families and six additional US families. No mutations were identified.

Familial and sporadic cases of nasopharyngeal carcinoma in Taiwan

BACKGROUND

Nasopharyngeal carcinoma (NPC) has a striking geographic/ethnic distribution, with especially high rates among southern Chinese. Previous studies have indicated that a family history of NPC is associated with increased risk and noted familial clustering in low-risk populations.

MATERIALS AND METHODS

We investigated differences between sporadic and familial cases of NPC in a case-control study of 375 histologically confirmed NPC cases (99% response rate) and 328 age-, sex-, and geographically-matched controls (88% response rate). All participants answered a detailed risk factor interview and donated blood for EBV and CYP 2E1 testing.

RESULTS

Subjects with a first degree relative with NPC had on odds ratio (OR) of 7.6 (95% confidence interval (CI) = 2.3-25), while those with a family history of any other cancer had only a slightly elevated risk of disease (OR = 1.4; 95% CI = .93-2.2). Of the cases, 25 (6.7%) were familial--having at least one first degree relative with NPC. No significant difference was seen between familial and sporadic cases with respect to sex, age, ethnicity, histology or stage. There was a nonsignificant (p = 0.16) increase in T1N2 tumors among familial cases, suggesting a more aggressive tumor. Family history of other cancers, EBV serologies, or the distribution of the RsaI c2 form of the allele of cytochrome P450 2E1 were also not significantly different between the two groups.

CONCLUSIONS

In conclusion, while genetic factors are likely to play an important role in NPC pathogenesis, our results provide little evidence that a familial form of NPC exists with characteristics notably distinct from sporadic cases.

Familial eosinophilia maps to the cytokine gene cluster on human chromosomal region 5q31-q33

Familial eosinophilia (FE) is an autosomal dominant disorder characterized by peripheral hypereosinophilia of unidentifiable cause with or without other organ involvement. To localize the gene for FE, we performed a genomewide search in a large U.S. kindred, using 312 different polymorphic markers. Seventeen affected subjects, 28 unaffected bloodline relatives, and 8 spouses were genotyped. The initial linkage results from the genome scan provided evidence for linkage on chromosome 5q31-q33. Additional genotyping of genetic markers located in this specific region demonstrated significant evidence that the FE locus is situated between the chromosome 5q markers D5S642 and D5S816 (multipoint LOD score of 6.49). Notably, this region contains the cytokine gene cluster, which includes three genes-namely, those for interleukin (IL)-3, IL-5, and granulocyte/macrophage colony-stimulating factor (GM-CSF)-whose products play important roles in the development and proliferation of eosinophils. These three cytokine genes were screened for potential disease-specific mutations by resequencing of a subgroup of individuals from the present kindred. No functional sequence polymorphisms were found within the promoter, the exons, or the introns of any of these genes or within the IL-3/GM-CSF enhancer, suggesting that the primary defect in FE is not caused by a mutation in any one of these genes but, rather, is caused by another gene in the area.

Notochord regulates cardiac lineage in zebrafish embryos

We focus here upon regulation by the notochord of myocardial cell fate in zebrafish. Myocardial precursors, defined by lineage tracing in the living embryo, are in the lateral plate mesoderm adjacent to the notochord-prechordal plate junction. Interestingly, the anterior end of the notochord corresponds to the posterior extent of the heart progenitor field, defined by this lineage analysis. This suggested that the notochord might suppress, or the prechordal plate might enhance, the cardiogenic fate. Nkx2.5 expression is, in the zebrafish embryo, closely correlated with the position of myocardial precursors, which reside adjacent to the notochord-prechordal plate junction. This expression, however, is extinguished in the region posterior to this junction, a region normally not contributing cells to the heart. Laser ablation of the notochord tip between the 4-somite and 12-somite stage causes posterior expansion of the Nkx2. 5-expressing region. The ntl mutation of the notochord is associated with posterior extension of Nkx2.5 expression. Lineage tracking, by laser activation of caged fluoresceinated dextran, confirms that, normally, lateral plate cells next to the notochord do not contribute progeny to the heart. After anterior notochord ablation, these cells are redirected to a heart cell fate. These data suggest that the anterior notochord delimits the posterior extent of the heart field by suppressing the heart cell fate.

Junctional epidermolysis bullosa: diagnosis and management of a patient with the Herlitz variant

A case of Herlitz-type epidermolysis bullosa (EB) is reported. The baby was born after a normal, full-term pregnancy with blisters on his extremities. Over the next several months, progressive skin sloughing involving 95% of his body surface area developed, including gastrointestinal, laryngeal, tracheobronchial, and corneal involvement. The diagnosis of junctional EB, Herlitz type, was made using clinical, electron microscopic, and immunohistochemical criteria. Despite meticulous wound care, aggressive nutritional support, and continuous antimicrobial therapy, the baby died at 9 months of age. This report discusses the presentation, complications, and management of this unusual and tragic disease.

CDKN2A mutations in multiple primary melanomas

BACKGROUND

Germ-line mutations in the CDKN2A tumor-suppressor gene (also known as p16, p16INK4a, and MTS1) have been linked to the development of melanoma in some families with inherited melanoma. Whether mutations in CDKN2A confer a predisposition to sporadic (nonfamilial) melanoma is not known. In some patients with sporadic melanoma, one or more additional primary lesions develop, suggesting that some of these patients have an underlying genetic susceptibility to the cancer. We hypothesized that this predisposition might be due to germ-line CDKN2A mutations.

METHODS

We used the polymerase chain reaction, single-strand conformation polymorphism analysis, and direct DNA sequencing to identify germ-line mutations in the CDKN2A gene in patients with multiple primary melanomas who did not have family histories of the disease. A quantitative yeast two-hybrid assay was used to evaluate the functional importance of the CDKN2A variants.

RESULTS

Of 33 patients with multiple primary melanomas, 5 (15 percent; 95 percent confidence interval, 4 percent to 27 percent) had germ-line CDKN2A mutations. These included a 24-bp insertion at the 5' end of the coding sequence, three missense mutations (Arg24Pro, Met53Ile, and Ser56Ile), and a 2-bp deletion at position 307 to 308 (resulting in a truncated CDKN2A protein). In three families, CDKN2A mutations identical to those in the probands were found in other family members. In two families with mutations, we uncovered previously unknown evidence of family histories of melanoma.

CONCLUSIONS

Some patients with multiple primary melanomas but without family histories of the disease have germ-line mutations of the CDKN2A gene. The presence of multiple primary melanomas may signal a genetic susceptibility to melanoma not only in the index patient but also in family members, who may benefit from melanoma-surveillance programs.

Familial eosinophilia: clinical and laboratory results on a U.S. kindred

We describe a five-generation kindred with familial eosinophilia (FE; MIM131400), characterized by the occurrence of sustained eosinophilia of unidentifiable cause in multiple relatives. The inheritance pattern is consistent with an autosomal dominant pattern. Among 52 related subjects studied, 19 were affected and 33 were unaffected. Ten unaffected spouses were also evaluated. Four subjects with sustained eosinophilia were diagnosed with cardiac abnormalities and two of them also had neurologic symptoms. In comparison with the unaffected or spouses, evaluation of complete blood counts showed that the affected relatives had, as expected, significantly higher white cell (P < 0.005) and absolute eosinophil counts (P < 0.001) and lower red cell counts (P < 0.05). Evaluation of serum cytokine levels (IL-5, IL-3, and granulocyte-macrophage colony-stimulating factor (GMCSF) and serology for parasitic helminth infection demonstrated no differences between the affected and unaffected individuals; no individuals studied had serologic evidence for parasitic infection. There were also no differences in anti-nuclear antibody, serum cobalamin (vitamin B12) level, immunoglobulin level, leukocyte alkaline phosphatase, rheumatoid factor, HLA analysis, and stool findings for ova and parasites. Among eight affected persons who had peripheral blood or bone marrow karyotype analysis, two carried the same chromosome abnormality, a pericentric inversion of chromosome 10, inv (10) (p11.2q21.2). A gene mapping study is currently underway to study the underlying genetic mechanism(s) of this syndrome.

RPA2, a gene for the 32 kDa subunit of replication protein A on chromosome 1p35-36, is not mutated in patients with familial melanoma linked to chromosome 1p36

Although some cases of dysplastic naevi (DN) and familial melanoma have been linked to anonymous markers on chromosome 1p36, the gene has not been identified. A candidate gene, RPA2, which codes for the 32 kDa subunit of replication protein A, is located in the 1p35-36 region. We examined the RPA2 gene in seven lymphoblastoid cell lines from members of melanoma-prone families linked to chromosome 1p36. Southern and Northern blot analyses showed the DNA and RNA bands were of normal size and intensity. DNA sequencing demonstrated no nucleotide alterations in the RPA2 cDNA. Western blot analysis exhibited normal electrophoretic migration and intensity of the RPA2 protein. These results indicate that alterations do not occur in the RPA2 gene in these DN/familial melanoma families linked to chromosome 1p36.

Allelic imbalance, including deletion of PTEN/MMACI, at the Cowden disease locus on 10q22-23, in hamartomas from patients with Cowden syndrome and germline PTEN mutation

Cowden disease (CD) is a rare, autosomal dominant inherited cancer syndrome characterized by multiple benign and malignant lesions in a wide spectrum of tissues. While individuals with CD have an increased risk of breast and thyroid neoplasms, the primary features of CD are hamartomas. The gene for CD has been mapped by linkage analysis to a 6 cM region on the long arm of chromosome 10 at 10q22-23. Loss of heterozygosity (LOH) studies of sporadic follicular thyroid adenomas and carcinomas, both component tumors of CD, have suggested that the putative susceptibility gene for CD is a tumor suppressor gene. Somatic missense and nonsense mutations have recently been identified in breast, prostate, and brain tumor cell lines in a gene encoding a dual specificity phosphatase, PTEN/MMACI, mapped at 10q23.3. Furthermore, germline PTEN/MMACI mutations are associated with CD. In the present study, 20 hamartomas from 11 individuals belonging to ten unrelated families with CD have been examined for LOH of markers flanking and within PTEN/MMACI. Eight of these ten families have germline PTEN/MMACI mutations. LOH involving microsatellite markers within the CD interval, and including PTEN/MMACI, was identified in two fibroadenomas of the breast, a thyroid adenoma, and a pulmonary hamartoma belonging to 3 to 11 (27%) of these patients. The wild-type allele was lost in these hamartomas. Semi-quantitative PCR performed on RNA from hamartomas from three different tissues from a CD patient suggested substantial reduction of PTEN/MMACI RNA levels in all of these tissues. The LOH identified in samples from individuals with CD and the suggestion of allelic loss and reduced transcription in hamartomas from a CD patient provide evidence that PTEN/MMACI functions as a tumor suppressor in CD.

Second cancers after medulloblastoma: population-based results from the United States and Sweden

Medulloblastoma, one of the most common central nervous system (CNS) tumors in children, requires aggressive multimodality therapy including surgery, radiation therapy, and occasionally chemotherapy. Given its intensive treatment regimen and improved survival during the past 20 years, it is likely that a cohort of survivors will result who may incur consequences of therapy, including a second cancer. We used population-based data from the United States and Sweden to estimate risks of second neoplasms in patients with histologically confirmed medulloblastoma (n = 1,262). Overall, there was a 5.4-fold excess of second neoplasms (95 percent confidence interval = 3.3-8.4) based on 20 observed and 3.7 expected cancers. The second cancers occurred eight to 432 months after initial diagnosis (median, 73 months) with significantly elevated ratios for all intervals examined except for less than one year after initial diagnosis. Significantly elevated risks were seen for cancers of the salivary glands, cervix uteri, brain and CNS, thyroid gland, and acute lymphoblastic leukemia. Of the 15 second cancers with treatment data, seven occurred in the radiation field or within areas of scatter while two others may have been radiation-related. Although based on small numbers of second cancers, the results suggest that as survival increases, some patients with medulloblastoma will have an increased risk of a second cancer, particularly a radiation-related cancer. Thus, as survival improves, late-occurring consequences of diagnosis and treatment will need to be carefully assessed. Identification of patients hypersensitive to radiation therapy, such as those with Gorlin Syndrome, should also be attempted in order to reduce the sequelae from intensive radiation exposure.

Hypermutability of UV-treated plasmids in dysplastic nevus/familial melanoma cell lines

Members of cutaneous melanoma (CM) families with dysplastic nevi (DN) are at high risk of developing CM. Using a shuttle vector plasmid, pSP189, cell lines from three patients with CM plus DN were previously found to have elevated post-UV plasmid mutability. To investigate familial occurrence of this cellular phenotype, we examined post-UV plasmid mutability in 31 lymphoblastoid cell lines from 6 familial CM kindreds. In comparison to 16 normal control lines, we found an abnormally elevated post-UV plasmid mutability in cell lines from 13 of 13 patients with CM plus DN (P = 1.5 x 10(-8)) and from 5 of 8 patients with DN only (P = 0.001). Elevated spontaneous plasmid mutation frequency (MF) was also present in cell lines from six of the CM plus DN patients (P = 0.002) and three of the DN-only patients (P = 0.028). However, cell lines from two patients with CM without DN had normal post-UV plasmid MF. Although not specific for CM patients, of 27 cell lines with elevated post-UV plasmid MF, only 8 were from donors who did not have CM + DN or DN (19 of 24 versus 8 of 28; P = 0.0003). This study indicates that post-UV plasmid hypermutability is a laboratory marker for members of melanoma-prone families and suggests that patients with familial CM have a defective mechanism for handling UV-induced DNA damage.

The genetics of melanoma

OBJECTIVES

To review the current status and recent advances of genetic epidemiology research in familial melanoma, and the implications for primary and secondary prevention of melanoma.

DATA SOURCES

Research studies, review articles, and book chapters pertaining to melanoma susceptibility factors.

CONCLUSION

Molecular genetic studies examining candidate genes for melanoma are being pursued vigorously. Considering the complexities and heterogeneity in the genetics of familial melanoma, predictive testing is not currently recommended as an established method for identifying individuals with a genetic predisposition to melanoma.

IMPLICATIONS FOR NURSING PRACTICE

An understanding of the genetics of melanoma will help oncology nurses in translating the appropriate clinical implications for primary and secondary prevention related to melanoma.

Affected members of melanoma-prone families with linkage to 9p21 but lacking mutations in CDKN2A do not harbor mutations in the coding regions of either CDKN2B or p19ARF

Mutations in the gene encoding the cell cycle inhibitor CDKN2A have been identified in some melanoma kindreds linked to 9p21. However, many such families show no evidence of mutations in the coding regions of CDKN2A. In this study, we examined whether two other potential tumor suppressors, CDKN2B and p19ARF, which also map within the 9p21 region, play a role in the development of familial melanoma. We found no mutations in the coding regions of either gene in melanoma-prone families with evidence of linkage to 9p21. We conclude either that another melanoma susceptibility gene exists within this chromosomal area or that mutations in noncoding regions of CDKN2A, CDKN2B, or p19ARF predispose to melanoma.

Nevoid basal cell carcinoma syndrome with medulloblastoma in an African-American boy: a rare case illustrating gene-environment interaction

We present an 8-year-old African-American boy with medulloblastoma and nevoid basal cell carcinoma syndrome (NBCCS) who exhibited the radiosensitive response of basal cell carcinoma (BCC) formation in the area irradiated for medulloblastoma. Such a response is well-documented in Caucasian NBCCS patients with medulloblastoma. The propositus was diagnosed with medulloblastoma at the age of 2 years and underwent surgery, chemotherapy, and craniospinal irradiation. At the age of 6 years, he was diagnosed with NBCCS following his presentation with a large odontogenic keratocyst of the mandible, pits of the palms and soles and numerous BCCs in the area of the back and neck that had been irradiated previously for medulloblastoma. Examination of other relatives showed that the propositus' mother also had NBCCS but was more mildly affected; in particular, she had no BCCs. This case illustrates complex gene-environment interaction, in that increased skin pigmentation in African-Americans is presumably protective against ultraviolet, but not ionizing, radiation. This case and other similar cases in the literature show the importance of considering NBCCS in the differential diagnosis of any patient who presents with a medulloblastoma, especially before the age of 5 years, and of examining other close relatives for signs of NBCCS to determine the patient's at-risk status. Finally, for individuals who are radiosensitive, protocols that utilize chemotherapy in lieu of radiotherapy should be considered.

Clinical manifestations in 105 persons with nevoid basal cell carcinoma syndrome

Nevoid basal cell carcinoma syndrome (NBCC; Gorlin syndrome), an autosomal dominant disorder linked to 9q22.3-q31, and caused by mutations in PTC, the human homologue of the Drosophila patched gene, comprises multiple basal cell carcinomas, keratocysts of the jaw, palmar/plantar pits, spine and rib anomalies and calcification of the falx cerebri. We reviewed the findings on 105 affected individuals examined at the NIH since 1985. The data included 48 males and 57 females ranging in age from 4 months to 87 years. Eighty percent of whites (71/90) and 38% (5/13) of African-Americans had at least one basal cell carcinoma (BCC), with the first tumor occurring at a mean age of 23 (median 20) years and 21 (median 20) years, respectively. Excluding individuals exposed to radiation therapy, the number of BCCs ranged from 1 to > 1,000 (median 8) and 1 to 3 (median 2), respectively, in the 2 groups. Jaw cysts occurred in 78/105 (74%) with the first tumor occurring in 80% by the age of 20 years. The number of total jaw cysts ranged from 1 to 28 (median 3). Palmar pits and plantar pits were seen in 87%. Ovarian fibromas were diagnosed by ultrasound in 9/52 (17%) at a mean age of 30 years. Medulloblastoma occurred in 4 patients at a mean age of 2.3 years. Three patients had cleft lip or palate. Physical findings include "coarse face" in 54%, relative macrocephaly in 50%, hypertelorism in 42%, frontal bossing in 27%, pectus deformity in 13%, and Sprengel deformity in 11%. Important radiological signs included calcification of the falx cerebri in 65%, of the tentorium cerebelli in 20%, bridged sella in 68%, bifid ribs in 26%, hemivertebrae in 15%, fusion of the vertebral bodies in 10%, and flame shaped lucencies of the phalanges, metacarpal, and carpal bones of the hands in 30%. Several traits previously considered components of the syndrome (including short fourth metacarpal, scoliosis, cervical ribs and spina bifida occulta) were not found to be significantly increased in the affected individuals. This study delineates the frequency of the clinical and radiological anomalies in NBCC in a large population of US patients and discusses guidelines for diagnosis and management.

Femoral venous access is safe in burned children: an analysis of 224 catheters

OBJECTIVE

To document the incidence of septic and mechanical complications associated with femoral venous catheters in a subgroup of patients thought to be at particularly high risk of both: young children with large burns.

DESIGN

An analysis of data collected prospectively on all femoral venous catheters placed during a 4-year period at a regional pediatric burn facility.

RESULTS

There were 224 femoral catheters placed in 86 children with an average age of 5.3 +/- 5.1 years and an average burn size of 38% +/- 23%. Catheters were left in place for a mean duration of 5.7 days. Catheter-related sepsis occurred with 4.9% of the catheters, and mechanical complications occurred in 3.5% of the patients. There was no statistically significant association between the risk of catheter sepsis and the placement of catheters through burned versus unburned skin. Similarly, the risk of sepsis was equivalent between lines placed over a guide wire and those placed of a new site.

CONCLUSION

Femoral venous catheters are safe in burned children and are associated with a low incidence of infectious and mechanical complications.

Apparent anticipation in familial melanoma

Genetic anticipation refers to progressively earlier age at diagnosis (AAD) and/or increasing severity of a disorder in successive generations. Previous examination of 23 familial melanoma kindreds revealed evidence for a dramatic reduction in AAD in successive generations. To further evaluate evidence for anticipation, we examined the AAD, number of tumours, and tumour thickness in affected parent-offspring (P-O) pairs from these 23 kindreds. Number of tumours and tumour thickness were also evaluated by generation. There were statistically significant intergenerational differences for AAD and number of tumours in the 47 affected P-O pairs. Median AAD decreased from 48 years to 28 years. The median AAD in the offspring (AADo) of a parent with CMM (median 28, mean 29.3 +/- 10.1 years, n = 51) was significantly different from the median AADo of a parent without CMM (42, 42.3 +/- 13.9 years, n = 55) (P < 0.001). In addition, parents with AAD less than the median of 48 years had offspring with a median AAD (26, 25.8 +/- 8.5 years, n = 21) significantly different from those of parents with AAD > or = 48 years (32, 34.5 +/- 10.2 years, n = 26) (P = 0.005). Ninety-four percent (44/47) of the P-O pairs showed positive anticipation, with 62% showing anticipation of > 15 years. There was little difference based on the affected parent's sex. In the 106 CMM cases there were no significant differences in tumour number (P = 0.08) or tumour thickness (P = 0.85) by generation. Number of tumours was however significantly different in cases with AAD < 34 years (n = 52, median 1.5, mean 2.3 +/- 2.4) vs cases with AAD > or = 34 years (n = 54, 1.0, 1.6 +/- 1.7) (P < 0.001). Thus these 23 familial melanoma kindreds showed evidence for anticipation as defined by a decrease in AAD in successive generations. Although increased surveillance may partly explain the results, additional studies should evaluate melanoma risk factors, genetic and/or environmental, across generations to examine the reasons for the apparent anticipation.