Serum lipase levels as a diagnostic marker in cystic fibrosis patients with normal or borderline sweat tests.

Patients with normal or borderline sweat test present a diagnostic challenge. In spite of the availability of different methods such as genetic analysis and measurements of nasal potential difference, uncertainty in diagnosing cystic fibrosis (CF) in some patients still exists. Neonates with CF have high serum lipase levels, which decline over time in pancreatic-insufficient patients, whereas pancreatic-sufficient patients demonstrate high serum lipase levels beyond infancy. Because patients with borderline or normal sweat test are almost always pancreatic sufficient, this study was aimed to assess whether serum lipase levels may be of help in establishing the diagnosis of CF in these patients. Serum lipase levels were measured in 100 CF patients and in 17 healthy individuals. Patients were grouped according to their genotype. Group A patients (n = 70) carried two mutations previously found to be associated with a pathologic sweat test and pancreatic insufficiency (delta F508, W1282X, G542X, N1303K, S549R). Group B (n = 30) were compound heterozygote patients who carried one mutation known to cause mild disease with borderline or normal sweat tests and pancreatic sufficiency (3849+10kb C-->T, 5T). Group C included 17 healthy controls. Serum lipase levels ranged between 2 and 104.4 U/L (mean +/- SD 16.9 +/- 14.7), 6.1-200 U/L (mean +/- SD 53.9 +/- 47.9), and 8.5-27.8 U/L (mean +/- SD 16.9 +/- 5.1) in Groups A, B, and C, respectively, with some overlapping between groups. The distribution of lipase levels was significantly different in Group B vs Groups A and C (P < 0.01). High lipase levels were found in 63.3% (19/30) of Group B patients, but in only 4.3% (3/70) and 0% (0/17) of Group A and C, respectively. Lipase levels were found to be inversely related to sweat chloride concentrations (r = -0.19, P < 0.05). Patients with borderline or normal sweat tests had high lipase levels, whereas low lipase levels were associated with pathologic sweat tests. Our findings indicate that the serum lipase level is genetically determined and that it has a useful role in the diagnosis of CF. Thus, in patients with borderline sweat tests and high lipase levels, the diagnosis of CF should be considered.

Serum CA 19-9 levels as a diagnostic marker in cystic fibrosis patients with borderline sweat tests.

Patients with normal or borderline sweat tests present a diagnostic challenge. In spite of the availability of genetic analysis and measurement of nasal potential difference, there is still uncertainty in diagnosing cystic fibrosis in some patients. CA 19-9 is a tumor-associated antigen whose levels were previously found to be elevated in some cystic fibrosis patients. We investigated whether serum CA 19-9 levels can contribute to establishing the diagnosis of cystic fibrosis in patients with a borderline sweat test, and evaluated the influence of different clinical variables on CA 19-9 levels. Serum CA 19-9 levels were measured in 82 cystic fibrosis patients grouped according to their genotype and in 38 healthy individuals. Group A included 50 patients who carried two mutations previously found to be associated with a pathological sweat test and pancreatic insufficiency (DeltaF508, W1282X, G542X, N1303K, and S549R). Group B included 13 compound heterozygote cystic fibrosis patients who carried one mutation known to cause mild disease with a borderline or normal sweat test and pancreatic sufficiency (3849+10kb C-->T, 5T). Group C included 38 normal controls. Nineteen cystic fibrosis patients carried at least one unidentified mutation. An association between CA 19-9 levels and age, pulmonary function, pancreatic status, sweat chloride, previous pancreatitis, serum lipase, meconium ileus, distal intestinal obstruction, liver disease, and diabetes was investigated. The distribution of CA 19-9 levels was significantly different between the three groups ( p<0.01); high CA 19-9 levels were found in 60% (30/50) of group Apatients and in 46.6% (6/13) of group B patients, but in only 5.2% (2/38) of the controls. CA 19-9 levels were inversely related to forced expiratory volume in 1 s, while no association was found with the other clinical parameters examined. Our findings suggest that the serum CA 19-9 in cystic fibrosis patients originates in the respiratory system, and has a useful ancillary role, particularly when diagnostic uncertainty exists. Hence, the diagnosis of cystic fibrosis should be considered in patients with borderline sweat tests and high CA 19-9 levels, but normal levels do not exclude cystic fibrosis.

Highly variable incidence of cystic fibrosis and different mutation distribution among different Jewish ethnic groups in Israel.

The incidence of cystic fibrosis (CF) and the frequency of disease-causing mutations varies among different ethnic and geographic populations. The Jewish population around the world is comprised of two major ethnic groups; Ashkenazi and non-Ashkenazi. The latter is further classified according to country of origin. In this study, we analyzed the incidence of CF and the distribution of CF mutations in the general Jewish population in Israel and in most of the Jewish ethnic subgroups. The disease frequency varies considerably among the latter. Among Ashkenazi Jews, the frequency of CF is 1:3300, which is similar to the frequency in most Caucasian populations. Among non-Ashkenazi Jews, the disease occurs at a similar frequency among Jews from Libya (1:2700), Georgia (1:2700), Greece and Bulgaria (1:2400), but is rare in Jews from Yemen (1:8800), Morocco (1:15000), Iraq (1:32000), and Iran (1:39000). So far, only 12 mutations have been identified in Israeli Jews, and this enables the identification of 91% of the CF chromosomes in the entire Jewish CF population. However, in each Jewish ethnic group, the disease is caused by a different repertoire of mutations. The frequency of identified mutations is high in Ashkenazi Jews (95%), and in Jews originating from Tunisia (100%), Libya (91%), Turkey (90%), and Georgia (88%). However, a lower frequency of mutations can be identified in Moroccan (85%), Egyptian (50%), and Yemenite (0%) Jews. For genetic counseling of a Jewish individual, it is necessary to calculate the residual risk according to ethnic origin. Carrier screening of healthy Jewish individuals is currently feasible for Ashkenazi Tunisian, Libyan, Turkish, and Georgian Jews. These results provide the required information for genetic counseling of Jewish CF families and screening programs of Jewish populations worldwide.

Mild cystic fibrosis and normal or borderline sweat test in patients with the 3849 + 10 kb C-->T mutation.

Different mutations in the cystic fibrosis (CF) gene appear to contribute to heterogeneity of the CF phenotype. We investigated 15 patients with CF who have the 3849 + 10 kb C-->T mutation. All were Ashkenazi Jews. Their clinical features were compared with those of CF patients with the delta F508/delta F508, W1282X/W1282X, W1282X/delta F508 mutations, which are known to be associated with a severe disease. Patients with the 3849 + 10 kb mutation were older, had been diagnosed as having CF at a more advanced age, and were in a better nutritional state. Sweat chloride values were normal (below 60 mmol/L) in 5 3849 + 10 kb patients (33%). 4 of these patients and 6 others (total 66%) had normal pancreatic function. However, age-adjusted pulmonary function did not differ between the two groups. None of the patients with 3849 + 10 kb C-->T had had meconium ileus or had liver disease or diabetes mellitus. We conclude that this mutation is associated with a mild type of CF.