Clinical genetics in transition-a comparison of genetic services in Estonia, Finland, and the Netherlands

Genetics has traditionally enabled the reliable diagnosis of patients with rare genetic disorders, thus empowering the key role of today's clinical geneticists in providing healthcare. With the many novel technologies that have expanded the genetic toolkit, genetics is increasingly evolving beyond rare disease diagnostics. When placed in a transition context-like we do here-clinical genetics is likely to become a fully integral part of future healthcare and clinical genetic expertise will be required increasingly outside traditional clinical genetic settings. We explore transition effects on the thinking (culture), organizing (structure), and performing (practice) in clinical genetics, taking genetic healthcare in Estonia, Finland, and the Netherlands as examples. Despite clearly distinct healthcare histories, all three countries have initially implemented genetic healthcare in a rather similar fashion: as a diagnostic tool for predominantly rare congenital diseases, with clinical geneticists as the main providers. Dynamics at different levels, such as emerging technologies, biobanks and data infrastructure, and legislative frameworks, may require development of a new system attuned with the demands and (historic) context of specific countries. Here, we provide an overview of genetic service provisions in Estonia, Finland, and the Netherlands to consider the impact of historic and recent events on prospective developments in genetic healthcare.

APOE and AGT in the Finnish p.Arg133Cys CADASIL population

BACKGROUND

CADASIL is an inherited systemic small vessel disease, the affected status of brain vessels leading to subcortical vascular dementia. The defective gene is NOTCH3 in which over 230 different pathogenic mutations have been identified. The clinical course of CADASIL is highly variable even within families. Previous studies have shown that additional genetic factors modify the phenotype.

AIMS AND METHODS

Altogether, 134 Finnish CADASIL patients with p.Arg133Cys mutation were analysed for possible associations between the apolipoprotein E (APOE) genotype, angiotensinogen (AGT) p.Met268Thr polymorphism or neutral p.Ala202Ala NOTCH3 polymorphism and earlier first-ever stroke or migraine.

RESULTS

We found no association between the APOE genotypes, AGT polymorphism, NOTCH3 polymorphism and earlier first-ever stroke or migraine.

CONCLUSIONS

The APOE, AGT and NOTCH3 polymorphism did not modify the onset of strokes or migraine in our CADASIL sample, which is one of the largest mutationally homogenous CADASIL populations published to date. International collaboration, pooled analyses and genomewide approaches are warranted to identify the genetic factors that modify the highly variable CADASIL phenotype.

The return of unexpected research results in a biobank study and referral to health care for heritable long QT syndrome

BACKGROUND

In this study, we examined how biobank study participants, who were found to have long QT syndrome (LQTS), a potentially life-threatening but treatable cardiac arrhythmia condition, experienced the process of disclosure of unexpected results and referral to health care.

METHODS

All 27 subjects with a LQTS mutation finding were asked to complete a questionnaire. Four participants did not uptake the re-testing and 5 others did not respond to the questionnaire. We received 17 questionnaires from 6 males and 11 females, aged 46-82; 5 of them were also willing to participate in qualitative interviews.

RESULTS

Of the respondents, 16/17 had experienced the process of receiving the results as positive and useful, especially if they had had symptoms. One respondent experienced the process negatively due to concerns related to informing her children. All respondents felt that genetic results should be reported back to the participants, while 2 indicated that this should occur only in the case of treatable conditions. Respondents had informed all of their children about the genetic condition, except 2 minors.

CONCLUSIONS

The respondents from a population biobank study who were informed about an unexpected genetic finding evaluated this process as mainly positive. They considered that delivering genetic information about a life-threatening but actionable condition has more beneficial than adverse consequences. The feedback policy for biobanks should include how and who is informed, advise treatment or care pathways for actionable findings, and it should also include suitable options for those who do not want to know about such findings.

Direct contact in inviting high-risk members of hereditary colon cancer families to genetic counselling and DNA testing

BACKGROUND

Identification of hereditary predisposition to cancer has limited significance if not followed by efficient cancer prevention in the family. Probands are traditionally left to inform their relatives about the increased risk, but distant relatives may remain uninformed. An approach to contacting directly at-risk persons assumed to be unaware of their increased cancer risk was taken. With cancer prevention as the ultimate goal, the study was aimed at investigating attitudes towards and psychosocial consequences of this novel strategy.

METHODS

In families with hereditary non-polyposis colorectal cancer (Lynch syndrome), 286 healthy adult relatives with a 50% risk of a predisposing mutation were contacted by letter. Of these, 112 participated in counselling and predictive testing. Baseline information and information obtained 1 month after the test for 73 respondents were compared with 299 corresponding subjects, approached via the proband (family-mediated approach in our previous study) in these families.

RESULTS

After the contact letter, 51% consented to the study. Of these, 92% approved of the direct contact and 33% had tried to seek information. In 34% of the mutation carriers, neoplasia was identified in the first post-test colonoscopy. Although post-test fear of cancer increased among the mutation carriers and decreased among noncarriers, almost all participants were satisfied with their decision to participate, independently of their test results, parallel to the family-mediated approach.

CONCLUSION

In this large-scale study, relatives in cancer families were actively contacted to inform them of the condition and genetic counselling. Their attitudes were encouraging, and the psychosocial consequences were similar to the family-mediated approach. Our results suggest the appropriateness of direct contact as an alternative method of contact in cases of life-threatening treatable disease.

Breast and other cancers in 1445 blood relatives of 75 Nordic patients with ataxia telangiectasia

Epidemiological studies have consistently shown elevated rates of breast cancer among female blood relatives of patients with ataxia telangiectasia (AT), a rare autosomal recessive disease. A large proportion of the members of AT families are carriers of AT-causing gene mutations in ATM (Ataxia Telangiectasia Mutated), and it has been hypothesised that these otherwise healthy carriers are predisposed to breast cancer. This is an extended and enlarged follow-up study of cancer incidence in blood relatives of 75 patients with verified AT in 66 Nordic families. Blood relatives were identified through population registry linkages, and the occurrence of cancer was determined from cancer registry files in each country and compared with national incidence rates. The ATM mutation carrier probabilities of relatives were assigned from the combined information on location in family, consanguinity, if any, and supplementary carrier screening in some families. Among the 1445 blood relatives of AT patients, 225 cancers were observed, with 170.4 expected, yielding a standardised incidence ratio (SIR) of 1.3 (95% confidence interval (CI), 1.1-1.4). Invasive breast cancer occurred in 34 female relatives (SIR, 1.7; 95% CI, 1.2-2.4) and was diagnosed in 21 women before the age of 55 years (SIR, 2.9; 95% CI, 1.8-4.5), including seven mothers of probands (SIR, 8.1; 95% CI, 3.3-17). When the group of mothers was excluded, no clear relationship was observed between the allocated mutation carrier probability of each family member and the extent of breast cancer risk. We concluded that the increased risk for female breast cancer seen in 66 Nordic AT families appeared to be restricted to women under the age of 55 years and was due mainly to a very high risk in the group of mothers. The findings of breast cancer risk in mothers, but not other likely mutation carriers, in this and other studies raises questions about the hypothesis of a simple causal relationship with ATM heterozygosity.

New options for prenatal diagnosis in autosomal recessive polycystic kidney disease by mutation analysis of the PKHD1 gene

Due to the poor prognosis of severe autosomal recessive polycystic kidney disease (ARPKD), there is a strong demand for prenatal diagnosis (PD). Reliable PD testing is possible by molecular genetic analysis only. Although haplotype-based analysis is feasible in most cases, it is associated with a risk of misdiagnosis in families without pathoanatomically proven diagnosis. Linkage analysis is impossible in families where DNA of the index patient is not available. Direct mutation analysis of the recently identified polycystic kidney and hepatic disease 1 gene opens new options in families to whom a reliable PD cannot be offered on the basis of linkage analysis. We for the first time report two cases with PD based on mutation detection, illustrating the new options for PD in ARPKD.

Genetic testing for maturity onset diabetes of the young: uptake, attitudes and comparison with hereditary non-polyposis colorectal cancer

AIMS/HYPOTHESIS

Mutations in hepatic nuclear factor 1alpha cause a monogenic form of diabetes, maturity onset diabetes of the young type 3 (MODY3). Our aim was (1) to assess the uptake of genetic testing for MODY3 and to determine factors affecting it, and (2) to compare attitudes to predictive genetic testing between families with MODY3 and a previously studied group at risk of hereditary non-polyposis colorectal cancer (HNPCC).

METHODS

Adult members of two extended MODY3 pedigrees, either with diabetes or a 50% risk of having inherited the mutation (n=144, age 18-60 years), were invited to an educational counselling session followed by a possibility to obtain the gene test result. Data were collected through questionnaires before counselling and 1 month after the test disclosure.

RESULTS

Eighty-nine out of 144 (62%) participated in counselling, and all but one wanted the test result disclosed. No significant sociodemographic differences were observed between the participants and non-participants. The counselling uptake was similar among diabetic and non-diabetic subjects. Uncertainty about the future and the risk for the children were the most common reasons to take the gene test. At follow-up, most subjects in both MODY3 (100%) and HNPCC (99%) families were satisfied with their decision to take the test and trusted the result. The majority of both diabetic and non-diabetic subjects considered that the MODY3 gene test should be offered either in childhood (50 and 37%) or as a teenager (30 and 37%).

CONCLUSIONS

Genetic testing for MODY3 was well accepted among both diabetic and non-diabetic participants. The subjects found the gene test reliable and they were satisfied with their decision regarding the predictive test.

Valproate embryopathy in three sets of siblings: further proof of hereditary susceptibility

The fetal valproate syndrome (FVS) is characterized by distinctive facial appearance, major and minor malformations, and developmental delay. Generally, only a small proportion of prenatally exposed children are affected. The authors describe three families in whom the occurrence of FVS in all the siblings strongly suggests hereditary susceptibility to valproic acid-induced adverse outcome. The risk for recurrence in a subsequent pregnancy may be high and should be taken into account in the counseling of parents and in considering drug treatment.

Psychological consequences of predictive genetic testing for hereditary non-polyposis colorectal cancer (HNPCC): a prospective follow-up study

Predictive genetic testing for cancer allows identification of those with the mutation (mutation positive) who should undergo cancer surveillance aiming at early detection of cancer and those without the mutation (mutation negative), whose unnecessary worry can be alleviated and who need not undergo frequent surveillance. However, there is a risk that predictive testing might have a harmful emotional impact on an individual. In the course of a predictive genetic testing protocol, we assessed general anxiety (by the State-Trait Anxiety Inventory [STAI]), fear of cancer and death, satisfaction with life and attitude to the future using a questionnaire survey in 271 individuals tested for hereditary non-polyposis colorectal cancer (HNPCC). Measurements were made before the first counseling (baseline), at the test disclosure session (STAI only) and 1 and 12 months after disclosure. Although at every measurement, the mutation-positive individuals were more afraid of cancer than those who were mutation negative, in both groups fear of cancer decreased significantly from baseline after disclosure. The mutation-positive subjects were more anxious than their counterparts immediately after the test disclosure, but the differences had disappeared at the follow-ups. In other variables, neither differences between the groups defined by mutation status nor changes with time were detected. Our findings suggest that counseling and testing relieve fear of cancer; no harmful emotional impact was detectable at the 1-year follow-up. To confirm these findings, however, the impact of testing should be studied after a longer interval. Furthermore, to evaluate the ultimate interpretation of these results, studies are needed to investigate the impact of fear of cancer on surveillance behavior among the mutation-positive subjects.

Loss-of-function mutations in SIP1 Smad interacting protein 1 result in a syndromic Hirschsprung disease

Hirschsprung disease (HD) has been described in association with microcephaly, mental retardation and characteristic facial features, delineating a syndrome possibly caused by mutations localized at chromosome 2q22--q23. We have analyzed a de novo translocation breakpoint at 2q22 in one patient presenting with this syndrome, and identified a gene, SIP1, which is disrupted by this chromosomal rearrangement. SIP1 encodes Smad interacting protein 1, a new member of the delta EF1/Zfh-1 family of two-handed zinc finger/homeodomain transcription factors. We determined the genomic structure and expression of the human SIP1 gene. Further analysis of four independent patients showed that SIP1 is altered by heterozygous frameshift mutations causing early truncation of the protein. SIP1, among other functions, seems to play crucial roles in normal embryonic development of neural structures and neural crest. Its deficiency, in altering function of the TGF beta/BMP/Smad-mediated signalling cascade, is consistent with some of the dysmorphic features observed in this syndrome, in particular the enteric nervous system defect that underlies HD.

Hirschsprung disease, mental retardation and dysmorphic facial features in five unrelated children

We report five patients with Hirschsprung disease, severe mental retardation and dysmorphic facial features including hypertelorism, prominent forehead and dysmorphic ears. All four boys had hypospadias. All had postnatally retarded growth. One of them had a de novo apparently balanced translocation 46,XY,t(2;11)(q22.2;q21). There are several reports on patients with Hirschsprung disease, mental retardation and various dysmorphic features. Some of them, especially those reported by Tanaka et al. [(1993) Pediatr Neurol 9:479-481], Lurie et al. [(1994) Genet Couns 5:11-14] and Mowat et al. [(1998) J Med Genet 35:617-623] closely resemble our patients suggesting that they have the same malformation syndrome.

Nephronophthisis and ulcerative colitis in siblings: a new association

Nephronophthisis (NPH) is a chronic tubulointerstitial nephritis leading to terminal renal insufficiency. The disease is heterogeneous, but usually the inheritance pattern is autosomal recessive. In 80% of cases, the disease is caused by a homozygous deletion in NPHP1 gene in chromosome 2q13. Ulcerative colitis is an inflammatory bowel disease with chronic diarrhea, rectal bleeding and characteristic histological findings. Its etiology is suggested to be multifactorial, consisting of genetic susceptibility and unknown exogenous factors. We present two siblings with NPH and ulcerative colitis. As NPH in this family is not linked to 2q13, this association may represent a new, syndromic form of NPH.

Involvement of BRCA1 and BRCA2 in breast cancer in a western Finnish sub-population

To date, two major familial breast cancer predisposition genes, BRCA1 and BRCA2, have been identified with hundreds of germ-line mutations, accounting for 5--10% of all breast cancer and 40--60% of all inherited breast cancer. Unexpectedly elevated incidence of breast cancer, especially in the older age classes, was observed in a Western Finnish region representing a relatively homogeneous population. This study was designed to test the hypothesis that there are inherited BRCA1 or BRCA2 mutations, which confer variable and/or age-dependent penetrance on carriers. Expecting a founder effect, we searched for geographical clustering of breast cancer cases and searched for associations between the affected phenotype and shared genomic segments in the BRCA1 and BRCA2 genomic regions. Our haplotype association study did not reveal any founder effects for either BRCA1 or BRCA2. However, there were two mutations prevalent in this geographical area with minor founder effects, BRCA2 T8555G and 999del5. This is one of the few geographically ascertained, population-based studies that indicate an overall frequency of BRCA1 and BRCA2 mutations at about 2--3% in all breast cancer cases. The geographical clustering of breast cancer cases was not explained by BRCA1 or BRCA2 genes.

Cancer in patients with ataxia-telangiectasia and in their relatives in the nordic countries

BACKGROUND

Epidemiologic studies of the families of patients with ataxia-telangiectasia (A-T), a recessive genetic neurologic disorder caused by mutation of the ATM gene, suggest that heterozygous carriers of an ATM mutation are at increased risk of cancer. A population-based study of cancer incidence in A-T families with unbiased selection and tracing of relatives would confirm this hypothesis.

METHODS

We conducted a study in the Nordic countries of 1218 blood relatives of 56 A-T patients from 50 families. The relatives were identified from population registries, and the occurrence of cancer was determined from cancer registry files in each country and compared with national incidence rates. All statistical tests were two-sided.

RESULTS

Among the 56 patients with A-T, we observed six cases of cancer (four leukemias and two non-Hodgkin's lymphomas) compared with 0.16 expected, yielding a standardized incidence ratio (SIR) of 37 (95% confidence interval [CI] = 13 to 80). Among the 1218 relatives, 150 cancers were recorded, with 126 expected (SIR = 1.19; 95% CI = 1.01 to 1.40). Invasive breast cancer occurred in 21 female relatives of A-T patients (SIR = 1.54; 95% CI = 0.95 to 2.36), including five of the 50 mothers (all of whom are obligate ATM mutation carriers) (SIR = 7.1; 95% CI = 2.3 to 17). Relatives who were less likely to be carriers of a mutant ATM allele had no increase or only a modest, statistically nonsignificant increase in the risk of breast cancer. There was no evidence of increased risk for cancer at any other site.

CONCLUSIONS

We confirmed the previously recognized high risk of lymphoma and leukemia in A-T patients. Our data are also consistent with an increased risk of breast cancer among blood relatives of A-T patients. The epidemiologic findings suggest, however, that, even if ATM mutations are responsible for some breast cancer cases, ATM is a relatively weak genetic risk factor for the disease.

A retrospective study of long-term psychosocial consequences and satisfaction after carrier testing in childhood in an autosomal recessive disease: aspartylglucosaminuria

Genetic carrier testing of children is usually not recommended. However, there are no data concerning long-term psychological consequences, experience, and satisfaction of those tested as well as their recall of the test results. We evaluated these items retrospectively 10-24 years after carrier testing performed in childhood. Study material comprised 25 families with aspatylglucosaminuria (AGU), an autosomal recessive disorder, with 35 healthy sibs from all parts of Finland tested for carriership during childhood between 1973 and 1987. Of these sibs, 25 participated in our study. The questionnaire comprised multiple-choice and open-ended questions. The psychosocial well-being of the study subjects measured by the RAND 36 item Health Survey 1.0 (RAND) was, in general, at least as good as that of controls, and showed no significant differences between carriers and non-carriers (p > 0.154). All tested individuals were satisfied with the fact that they had been tested and stated that the decision to perform carrier testing on a child can be made by the parents. Of the 25 tested, 23 knew and understood their test result correctly at the time of our study. Most of the tested individuals (60%) stated that the best time for carrier testing would be in the childhood or in the teen years. This study indicates that carrier testing in childhood for an autosomal recessive disorder (AGU) had caused no measurable disturbance of quality of life in adulthood, and those tested reported being satisfied. However, we do not recommend testing in childhood, as the result is not needed prior to the time for reproductive decisions.

Carrier testing of children for two X-linked diseases: A retrospective study of comprehension of the test results and social and psychological significance of the testing

OBJECTIVE

To evaluate long-term consequences of genetic carrier testing performed in childhood in terms of awareness and comprehension of the test result, and the social and psychological significance of such testing.

STUDY DESIGN

The families of 66 young females who had been tested for carriership during childhood between 1984 and 1988 were approached. Of the 66 families, 23 young females in families affected by Duchenne muscular dystrophy (DMD), 23 young females in families affected by hemophilia A (HA), and their mothers participated in our study. We used a questionnaire including multiple-choice and open-ended questions.

RESULTS

Of the young female participants tested in the families affected by DMD or HA, 65% knew their test results. Only 65% of DMD mothers and 78% of HA mothers remembered correctly the test results of their daughters. The majority (83%) of the young females tested sought no genetic counseling when reaching adulthood. The reason for this was not determined. Most (78%) reported that the test result had not influenced their lives, whereas some felt relieved to know they had not been carriers. Talking about hereditary disease in the family and between friends was open, and results of the carrier test had usually been told to friends.

CONCLUSION

Carrier testing was in most cases correctly understood and the matter openly discussed. Our results do not suggest that testing in childhood had caused serious harm to the young individuals tested. On the other hand, we found no obvious benefits from this early testing.

Characterization of ATM mutations in 41 Nordic families with ataxia telangiectasia

The Ataxia Telangiectasia Mutation (ATM) gene is mutated in the rare recessive syndrome Ataxia Telangiectasia (AT), which is characterized by cerebellar degeneration, immunodeficiency, and cancer predisposition. In this study, 41 AT families from Denmark, Finland, Norway, and Sweden were screened for ATM mutations. The protein truncation test (PTT), fragment length and heteroduplex analyses of large (0.8-1.2 kb) cDNA fragments were used. In total, 67 of 82 (82%) of the disease-causing alleles were characterized. Thirty-seven unique mutations were detected of which 25 have not previously been reported. The mutations had five different consequences for the ATM transcript: mutations affecting splicing (43%); frameshift mutations (32%); nonsense mutations (16%); small in-frame deletions (5%); and one double substitution (3%). In 28 of the probands mutations were found in both alleles, in 11 of the probands only one mutated allele was detected, and no mutations were detected in two Finnish probands. One-third of the probands (13) were homozygous, whereas the majority of the probands (26) were compound heterozygote with at least one identified allele. Ten alleles were found more than once; one Norwegian founder mutation constituted 57% of the Norwegian alleles. Several sequence variants were identified, none of them likely to be disease-causing. Some of them even involved partial skipping of exons, leading to subsequent truncation of the ATM protein.

Complete maternal isodisomy of chromosome 8 in an individual with an early-onset ileal carcinoid tumor

Uniparental disomy (UPD) is a condition in which diploid individuals possess a chromosome pair from a single parent. In some instances, UPD causes an abnormal phenotype due to imprinting effects, reduction to homozygosity at recessive disease loci, or trisomy mosaicism. Here we report the first account of an individual with apparently nonmosaic complete maternal isodisomy of chromosome 8. This individual was identified during routine genotyping in a genomewide search for type 2 diabetes susceptibility genes, although he does not have diabetes. He is of normal appearance, stature, and intelligence, but there is an unusual history of early onset ileal carcinoid. The discovery of other maternal UPD 8 cases will be necessary to define whether this condition causes a distinct phenotype.

Population-based molecular detection of hereditary nonpolyposis colorectal cancer

PURPOSE

Cancer morbidity and mortality can be dramatically reduced by colonoscopic screening of individuals with the hereditary nonpolyposis colorectal cancer (HNPCC) syndrome, creating a need to identify HNPCC. We studied how HNPCC identification should be carried out on a large scale in a sensitive and efficient manner.

PATIENTS AND METHODS

Colorectal cancer specimens from consecutive newly diagnosed patients were studied for microsatellite instability (MSI). Germline mutations in the MLH1 and MSH2 genes were searched for in MSI(+) individuals.

RESULTS

Among 535 colorectal cancer patients, 66 (12%) were MSI(+). Among these, 18 (3.4% of the total) had disease-causing germline mutations in MLH1 or MSH2. Among these 18 patients, five were less than 50 years old, seven had a previous or synchronous colorectal or endometrial cancer, and 15 had at least one first-degree relative with colorectal or endometrial cancer. Notably, 17 (94%) of 18 patients had at least one of these three features, which were present in 22% of all 535 patients. Combining these data with a previous study of 509 patients, mutation-positive HNPCC accounts for 28 (2.7%) of 1,044 cases of colorectal cancer, predicting a greater than one in 740 incidence of mutation-positive individuals in this population.

CONCLUSION

Large-scale molecular screening for HNPCC can be done by the described two-stage procedure of MSI determination followed by mutation analysis. Efficiency can be greatly improved by using three high-risk features to select 22% of all patients for MSI analysis, whereby only 6% need to have mutation analysis. Sensitivity is only slightly impaired by this procedure.

Spectrum of COL4A5 mutations in Finnish Alport syndrome patients

Alport syndrome (AS) is a hereditary kidney disorder, mainly caused by mutations in the X-chromosomal gene (COL4A5) encoding the type IV collagen a5 chain. In this study, detection of COL4A5 mutations was performed in 17 Finnish Alport syndrome families. Regions around the 51 previously known exons, as well as the two recently characterized exons 41A and 41B in COL4A5, were PCR-amplified from the patient DNA. Direct sequencing of the amplified products was performed and mutations were found in 12 families. None of the mutations involved exons 41A or 41B. Three of the mutations were potential splicing mutations, two of which were studied at the mRNA level. Seven of the mutations were single base substitutions, and two were deletions. In five families, no mutations were found.

Evaluation of a counselling protocol for predictive genetic testing for hereditary non-polyposis colorectal cancer

OBJECTIVES

To evaluate the feasibility of a reduced counselling programme for predictive genetic testing for hereditary non-polyposis colorectal cancer (HNPCC) in terms of counsellees' opinions on the extent and significance of genetic counselling and need for psychological support at different phases of the testing procedure.

DESIGN

Prospective follow up study with pre-test questionnaire assessment of background sociodemographic variables. The protocol comprised a pre-test counselling session, a period for reflection, and a test disclosure session. The outcome variables were studied by post-test questionnaires at one month and one year follow up.

SUBJECTS

Two hundred and seventy one high risk members of 36 families with HNPCC who attended both counselling sessions and completed the questionnaires.

RESULTS

The pre-test counselling was considered fairly or very useful by 89% of respondents and one post-test session was considered sufficient by over 80% of respondents at follow up. Fifty three percent would have used extra psychological support had it been offered with the counselling. On enquiry one year after receiving the test result, only 2% stated that the need for support was at its greatest at that time, while the majority (46%) reported that the need for support had been greatest at the moment of test disclosure.

CONCLUSIONS

A protocol that includes one comprehensive pre-test counselling session and a test disclosure session, supplemented with the option of professional psychological support, seems to be sufficient for both the educational and supportive needs of counsellees. Only a minority expressed a need for post-test follow up sessions, which suggests that, in this disorder, resources can be directed to the beneficial surveillance programmes rather than to extensive psychological support.

Autosomal recessive disorder otospondylomegaepiphyseal dysplasia is associated with loss-of-function mutations in the COL11A2 gene

Otospondylomegaepiphyseal dysplasia (OSMED) is an autosomal recessive skeletal dysplasia accompanied by severe hearing loss. The phenotype overlaps that of the autosomal dominant disorders-Stickler and Marshall syndromes-but can be distinguished by disproportionately short limbs, severe hearing loss, and lack of ocular involvement. In one family with OSMED, a homozygous Gly-->Arg substitution has been described in COL11A2, which codes for the alpha2 chain of type XI collagen. We report seven further families with OSMED. All affected individuals had a remarkably similar phenotype: profound sensorineural hearing loss, skeletal dysplasia with limb shortening and large epiphyses, cleft palate, an extremely flat face, hypoplasia of the mandible, a short nose with anteverted nares, and a flat nasal bridge. We screened affected individuals for mutations in COL11A2 and found different mutations in each family. Individuals from four families, including three with consanguineous parents, were homozygous for mutations. Individuals from three other families, in whom parents were nonconsanguineous, were compound heterozygous. Of the 10 identified mutations, 9 are predicted to cause premature termination of translation, and 1 is predicted to cause an in-frame deletion. We conclude that the OSMED phenotype is highly homogenous and results from homozygosity or compound heterozygosity for COL11A2 mutations, most of which are predicted to cause complete absence of alpha2(XI) chains.

Predictive genetic testing for hereditary non-polyposis colorectal cancer: uptake and long-term satisfaction

The aim of this prospective study was to assess the uptake of predictive genetic testing for hereditary non-polyposis colorectal cancer (HNPCC) and its associations with sociodemographic and other factors, and long-term satisfaction with taking the test. The test was offered to all high-risk members (n = 446) of 36 Finnish HNPCC families in which the mutation was known. The procedure comprised an educational counselling session, a period for reflection, and a test disclosure session. Data were collected by questionnaires sent before the educational counselling and 1 month and 1 year after the test disclosure. Of those eligible, 85% (n = 381) completed the first questionnaire study. Non-participation was more common among men living alone who had not participated in the clinical cancer surveillance programme. Of the 347 subjects who attended counselling, 334 (75% of all subjects) were actually tested. After logistic-regression analysis, the only significant factor predicting test acceptance proved to be employment status: those employed were more likely than others to accept the test (odds ratio = 2.25; 95% confidence intervals, 1.09 to 4.6 1). At follow-up, over 90% of the subjects were fully satisfied with the decision to take the test. In conclusion, acceptance of the test was considerably higher than in previously reported studies. We attribute this to our careful face-to-face individualized counselling, our health care system, and to attitudes of the Finnish population, which are generally favourable towards health care and disease prevention.

Carrier testing of children for two X-linked diseases: a retrospective evaluation of experience and satisfaction of subjects and their mothers

Carrier testing of children for inherited disease that will not affect the health of the children themselves but of their future children is generally regarded as problematic. In this retrospective study, we determined how young women had experienced genetic carrier testing when they were children. The families of 66 young females who had been tested for carriership during childhood between 1984 and 1988, were approached. Of them, 23 young females in families affected by Duchenne muscular dystrophy, and 23 young females in families affected by hemophilia A, and their mothers, participated in our study. We used a questionnaire including multiple-choice and open-ended questions. We recorded general attitudes to testing, satisfaction with testing, degree of trust in test results, making decisions regarding testing, privacy, and opinions about age at testing. Thirty-five out of 46 of the young women tested (76%) were satisfied with carrier testing in childhood. However, the young women in whom the test results had been uncertain were statistically more often unsatisfied with the testing than those who had been found or not found to be carriers (p = 0.002). In each group, the opinions of mothers were parallel to those of their daughters. Seventy-eight percent of daughters regarded carrier testing as a family matter in which parents can make a decision. About half of those tested recalled that they had been allowed to participate in decision-making in a satisfying way. Thirty-nine out of 46 (85%) of the young women tested, and 33/46 (72%) of the mothers, suggested that carrier testing should be performed in childhood or during teenage years.

Long-term prognosis of haemangioblastoma of the CNS: impact of von Hippel-Lindau disease

The aim was to assess the frequency of von Hippel-Lindau disease (VHL) and the long-term prognosis of VHL and non-VHL patients among 110 consecutive patients with haemangioblastoma (HB) of the CNS treated between 1953 and 1993 at one neurosurgical unit. To reveal VHL manifestations we performed a detailed clinical and radiological examination (neuraxis and abdomen) (61/110), VHL-gene mutation analysis (40/110), and collection of all available clinical, imaging, operative and autopsy data from the hospitals involved. All patients were followed-up with a median of 14 years (excluding 14 operative deaths), and no patient was lost to follow-up. Altogether 49 patients died during the follow-up. In the 14 VHL patients (13%), HB(s) of the CNS were detected at a median age of 33 years, retinal HB(s) at 39 years, and renal cell carcinoma (RCC) at 43 years. The frequency of VHL in patients operated on for HB(s) was 29% before the age of 25 years, 19% between 25 and 45 years, and only 2% after 45 years. HB patients not meeting the VHL criteria had internal organ cysts in 14%. One non-VHL patient (4%) had two adjacent HBs in the same cyst wall. The growth rates of non-VHL and VHL-related HBs were similar as indicated by the median time to recurrence and the proliferation indices (MIB-1). Recurrence of the HB in patients whose primary operation was considered radical developed in four of the 10 VHL patients at a median of 19 years, and in nine of the 74 non-VHL patients at a median of 11 years. The median length of life of all VHL and non-VHL patients was 46 and 63 years, respectively. In VHL, RCC and HBs were equal causes of death.

The burden of genetic disease and attitudes towards gene testing in Alport syndrome

We evaluated the burden of Alport syndrome (AS) and the attitudes towards gene testing in patients with AS and their healthy family members from 37 families using a multiple-choice questionnaire. We also evaluated how the disease affected the decision to have children and the information received about the syndrome. A total of 53 individuals responded to this questionnaire. The risk of renal insufficiency and the uncertainty of the prognosis were considered the worst components of AS. Many of the respondents felt that children should be informed about AS as soon as they start asking (45%), preferably by a parent (74%). Almost all of the respondents (96%) had a positive attitude towards genetic research, which in the opinion of the majority should be aimed at better treatment and diagnosis of the disease rather than developing methods for prenatal diagnosis (89% and 75% versus 43%). AS seems to be well tolerated; 28% and 19% of the respondents found abortion acceptable in cases of an affected male and female fetus, respectively. Our study indicates a desire for prenatal tests in order to predict the health of a future child rather than for selective abortion.

Carrier testing of children for two X linked diseases in a family based setting: a retrospective long term psychosocial evaluation

The question of whether genetic carrier testing should be performed on children has been the subject of much debate. However, one important element has been lacking from this debate. There has been practically no knowledge of how those tested in childhood have experienced carrier testing. Twenty three subjects in families affected by Duchenne muscular dystrophy and 23 in families affected by haemophilia A, all of whom had been tested during childhood for carriership in the Department of Medical Genetics, University of Helsinki, from 1984 to 1988, participated in our study. We investigated long term psychosocial consequences of carrier testing in childhood. A questionnaire relating to sociodemographic background and life situation was used, together with assessment of health related quality of life (HRQOL) using the RAND 36 item Health Survey 1.0 (RAND). RAND results showed that the emotional, social, and physical well being of the young female subjects was not statistically different from those of control female subjects at a similar age. We also found no statistically significant differences in means in any RAND dimension (p<0.146) between carriers, non-carriers, and a group in which carrier status was uncertain. However, two out of seven carriers reported that they were worried and three that they were slightly worried about the test result. Four out of 22 young female subjects in the uncertain group reported being worried and 11 reported being slightly worried.

Ocular findings in 34 patients with Alport syndrome: correlation of the findings to mutations in COL4A5 gene

PURPOSE

To describe the incidence and type of ocular findings of 34 patients with Alport syndrome and to analyze the association of gene defect in COL4A5 gene to ocular abnormalities found.

METHODS

A nationwide search of Alport syndrome patients was performed in Finland, and patients were invited to take part in a thorough ophthalmologic investigation.

RESULTS

A total of 34 Alport syndrome patients from 14 different pedigrees were examined, and ocular abnormalities were found in 32% of them. The visual acuities were normal except in 4 of the 34 patients. Six individuals had retinal flecks and 4 men had anterior lenticonus. In 57% of the pedigrees the defect in COL4A5 gene was known.

CONCLUSION

Ocular abnormalities were rare in childhood and increased with age. There was no correlation between the type of mutation and the type of ocular changes. In addition, the penetrance of the ocular findings varied considerably within most families.

Nephronophthisis in Finland: epidemiology and comparison of genetically classified subgroups

Nephronophthisis--medullary cystic kidney disease is a progressive chronic tubulointerstitial nephritis leading to terminal renal failure. About two thirds of the patients with familial juvenile nephronophthisis, an autosomal recessive disease, have a homozygous deletion at the gene locus on 2q13. Through a nationwide search, 59 patients were ascertained in Finland. The incidence was 1:61,800 live births when calculated over a 20-year period. Of the patients, 17 came from four families showing dominant inheritance and 37 patients from 28 apparently recessive families when classified by family history, clinical features or presence of a deletion on 2q13. Two were considered as new dominant mutations; three sporadic patients could not be classified. The most significant difference between the patients with deletions, patients without deletions but having recessive family history, and patients belonging to families with dominant inheritance was the age at first symptoms, at the start of dialysis and at transplantation. These facts will be of help in determining the mode of inheritance of a sporadic patient without a deletion.

Incidence of hereditary nonpolyposis colorectal cancer and the feasibility of molecular screening for the disease

BACKGROUND

Genetic disorders that predispose people to colorectal cancer include the polyposis syndromes and hereditary nonpolyposis colorectal cancer. In contrast to the polyposis syndromes, hereditary nonpolyposis colorectal cancer lacks distinctive clinical features. However, a germ-line mutation of DNA mismatch-repair genes is a characteristic molecular feature of the disease. Since clinical screening of carriers of such mutations can help prevent cancer, it is important to devise strategies applicable to molecular screening for this disease.

METHODS

We prospectively screened tumor specimens obtained from 509 consecutive patients with colorectal adenocarcinomas for DNA replication errors, which are characteristic of hereditary colorectal cancers. These replication errors were detected through microsatellite-marker analyses of tumor DNA. DNA from normal tissue from the patients with replication errors was screened for germ-line mutations of the mismatch-repair genes MLH1 and MSH2.

RESULTS

Among the 509 patients, 63 (12 percent) had replication errors. Specimens of normal tissue from 10 of these 63 patients had a germ-line mutation of MLH1 or MSH2. Of these 10 patients (2 percent of the 509 patients), 9 had a first-degree relative with endometrial or colorectal cancer, 7 were under 50 years of age, and 4 had had colorectal or endometrial cancer previously.

CONCLUSIONS

In this series of patients with colorectal cancer in Finland, at least 2 percent had hereditary nonpolyposis colorectal cancer. We recommend testing for replication errors in all patients with colorectal cancer who meet one or more of the following criteria: a family history of colorectal or endometrial cancer, an age of less than 50 years, and a history of multiple colorectal or endometrial cancers. Patients found to have replication errors should undergo further analysis for germ-line mutations in DNA mismatch-repair genes.

Molecular studies in Finnish patients with familial juvenile nephronophthisis exclude a founder effect and support a common mutation causing mechanism

Familial juvenile nephronophthisis (NPH) is an autosomal recessive tubulointerstitial kidney disease associated with formation of medullary and corticomedullary cysts. It progresses to end stage renal failure and its biochemical defect is unknown. An NPH locus has been assigned to a 2 cM interval on chromosome 2q13 by linkage studies. Homozygous deletions of approximately 250 kb have been detected in 80% of familial cases and 65% of sporadic cases and a common mutation mechanism has been suggested. We examined 14 Finnish families for the presence or absence of a deletion. After detecting a deletion in 12 patients belonging to nine families, we studied a possible founder effect by haplotype analysis using markers D2S340, D2S1889, and D2S1893. No common ancestral disease associated haplotype was found suggesting no founder effect. Results of pairwise linkage analyses were suggestive of linkage in the nine families with a deletion (lod scores of 1.39-3.89 at a recombination fraction of 0). Negative lod scores were obtained in the five families without a deletion suggesting that the disease locus in these families lies elsewhere. The end stage renal disease occurred at a more advanced age in patients without a deletion compared to patients with a deletion, indicating a phenotypic difference between these two groups.

Genetic control of serum IgE levels and asthma: linkage and linkage disequilibrium studies in an isolated population

Immunoglobulin E (IgE) concentration in serum is elevated in atopic diseases such as asthma. A large genomic region on chromosome 5 has previously been implicated in the control of IgE levels and bronchial hyperreactivity and may, therefore, harbor genes predisposing to asthma. In an effort to confirm this linkage and to delimit the critical region, we took advantage of an isolated founder subpopulation in Finland to study genetic linkage and haplotype associations. Sixteen polymorphic markers, including the Interleukin-4 and -9 genes (IL4, IL9), were physically ordered and genotyped in 157 nuclear families. Genetic linkage studies involving sib- and cousin-pair analyses found no evidence of genetic linkage between markers in 5q and either serum IgE levels or asthma. Haplotype association studies were also performed. Although initial inspection suggested the possibility of linkage disequilibrium in the region of IL9, we developed a rigorous permutation test for assessing association and determined that the association was no greater than would be expected by chance. Sequence analysis of the IL9 gene in three patients sharing a possibly conserved haplotype revealed a T113M coding polymorphism, but this variant showed no association with either serum IgE levels or asthma. We conclude that allelic variation at chromosome 5q31 is not likely to contribute to inheritance of serum IgE levels or the development of asthma in this Finnish subpopulation.

Breast cancer risk estimation in families with history of breast cancer

Among 288 breast cancer patients (118 with bilateral disease and 165 with diagnosis before 40 years of age), we identified 26 families with a history of breast cancer, including a minimum of three first- or second-degree relatives. Complete pedigrees with verified malignancy data from the Finnish cancer registry were constructed for 22 families. The median age at breast cancer diagnosis of the young probands (< 40 years of age) was 35 years and of bilateral probands was 54 years. The relatives of the young probands were diagnosed with breast cancer at a younger age (median age 54 years) than the relatives of the older (bilateral) probands (median age 60 years). Standard life-table methods were used to compare the risk of breast cancer in the family members with that of the general population. Among the relatives of the young probands, the increased breast cancer risk occurred in the early post-menopausal period, whereas the risk estimate for the relatives of the bilateral probands closely followed that of the general population. In both groups, however, those family members reaching the age of 80 years had a cumulative probability of over 50% of developing breast cancer. The standard life-table method proved useful when assessing the age-specific risk for familial breast cancer, taking into account numerous family members as well as their age at disease onset. This kind of analysis can be performed in populations for which reliable cancer registry data are available. It provides a useful tool for selecting individuals for imaging and mutation screening, counselling and experimental chemoprevention programmes.

Refined mapping of the Usher syndrome type III locus on chromosome 3, exclusion of candidate genes, and identification of the putative mouse homologous region

A locus for Usher syndrome type III (USH3; MIM No. 276902) was recently assigned to a 5-cM region on chromosome 3q. We constructed a yeast artificial chromosome contig that allowed us to position novel polymorphisms in the region. These were typed in a total of 32 pedigrees from a geographically isolated Finnish founder population in which a putative single ancestral USH3 mutation segregates. A multipoint linkage analysis assigned USH3 to a 4-cM region between D3S1555 and a novel marker D3S3625. By analysis of linkage disequilibrium and historical recombinations in 77 USH3 chromosomes, the location of the Finnish USH3 mutation could be narrowed to an approximately 1-cM interval between the markers D3S1299 and D3S3625. A gene for profilin-2 (PFN2) was mapped in the vicinity and excluded as a candidate for USH3 by sequencing. The putative mouse homolog of PFN2 was mapped to mouse chromosome 3, thus suggesting a localization for the mouse homolog of USH3.

Alport's syndrome in 78 patients: epidemiological and clinical study

In a nationwide study in Finland, 78 patients, 38 male and 40 female in 25 families, were found to have Alport's syndrome, corresponding to 1 in 53,000 live births. This frequency of clinically manifest Alport's syndrome was much lower than expected from earlier reports. This first sign of the disease was most often haematuria, but was sometimes proteinuria or hearing loss. These signs were detected at a similar median age in both boys and girls, namely 6.2 and 6.0 years, respectively. The patients were followed up over a median period of 12.1 years (range 0.1 - 34.0 years). The clinical course of the disease was more severe in the male subjects than in the female subjects: 53% of the males and 13% of the females developed terminal renal failure at median ages of 24.9 and 31.1 years, respectively. At the last observation, 34% males and 78% females were free of renal insufficiency at median ages of 10.3 and 26.8 years. Hearing loss was detected in 74% of the males and 5% of the females. Regarding the rate of deterioration of renal function, no statistically significant difference was noticed between males and females. The routine use of dialysis and transplantations has dramatically changed the life expectancy of the patients.

Molecular mapping of the putative gonadoblastoma locus on the Y chromosome

Based on the high incidence of gonadoblastoma in females with XY gonadal dysgenesis or 45,X/46,XY mosaicism, the existence of a susceptibility locus on the Y chromosome (GBY) has been postulated. We attempted to map GBY by making use of a recently developed dense map of Y-chromosomal sequence-tagged sites (STSs). In two female patients with gonadoblastoma, small marker chromosomes contained portions of the Y chromosome, and a single region of overlap could be defined extending from probe pDP97 in interval 4B, which contains the centromere, to marker sY182 in interval 5E of the proximal long arm. This interval is contained in a YAC contig that comprises approximately 4 Mb of DNA. Our findings confirm the previous localization of GBY and greatly refine it. The localization of GBY overlaps with the region to which a putative growth determinant, GCY, was recently assigned.

Clinical features of nine males with molecularly defined deletions of the Y chromosome long arm

Deletions of the long arm of the Y chromosome have previously been associated with azoospermia and short stature. We report the results of a detailed clinical and molecular study of nine males with partial deletions of Yq. Special emphasis was laid on congenital anomalies and dysmorphic features. Some of the patients have developmental problems or distinct facial features, namely a small chin and mouth, a high arched or cleft palate, downward slanting palpebral fissures, high nasal bridge, and dysmorphic ears. As far as we know, similar facial dysmorphism has not been previously described in association with del(Yq). These features are not, however, simply correlated to the size of the deletion. In none of these patients could evidence of aberrant Xq-Yq interchange be found.