[Diagnosis and treatment understanding of Waldenström macroglobulinemia in China: a cross-sectional study].

Objective: To conduct a nationwide physician survey to better understand clinicians' disease awareness, treatment patterns, and experience of Waldenström macroglobulinemia (WM) in China. Methods: This cross-sectional study was conducted from February 2022 to July 2022 by recruiting clinicians with WM treatment experience from hematology, hematology-oncology, and oncology departments throughout China. Quantitative surveys were designed based on the qualitative interviews. Results: The study included 415 clinicians from 219 hospitals spread across thirty-three cities and twenty-two provinces. As for diagnosis, the laboratory tests prescribed by physicians for suspected WM patients were relatively consistent (92% -99% recommendation for laboratory, 79% -95% recommendation for pathology, 96% recommendation for gene testing, and 63% -83% recommendation for imaging examination). However, from a physician's perspective, there was 22% misdiagnosis occurred in clinical practice. The rate of misdiagnosis was higher in lower-level hospitals than in tertiary grade A hospitals (29% vs 21%, P<0.001). The main reasons for misdiagnosis were that WM was easily confused with other diseases, and physicians lacked the necessary knowledge to make an accurate diagnosis. In terms of gene testing in clinical practice, 96% of participating physicians believed that WM patients would require gene testing for MYD88 and CXCR4 mutations because the results of gene testing would aid in confirming diagnosis and treatment options. In terms of treatment, 55% of physicians thought that the most important goal was to achieve remission, while 54% and 51% of physicians wanted to improve laboratory and/or examination results and extend overall survival time, respectively. Among patients with treatment indications, physicians estimated that approximately 21% of them refused to receive treatment, mainly owing to a lack of affordable care and disease awareness. When selecting the most appropriate treatment regimens, physicians would consider patient affordability (63% ), comorbidity (61% ), and risk level (54% ). Regimens containing Bruton tyrosine kinase inhibitor (BTKi) were most widely recommended for both treatment-naïve and relapsed/refractory patients (94% for all patients, 95% for treatment-naïve patients, and 75% for relapsed/refractory patients), and most physicians recommended Ibrutinib (84% ). For those patients who received treatment, physicians reported that approximately 23% of patients did not comply with the treatment regimen due to a lack of affordability and disease awareness. Furthermore, 66% of physicians believe that in the future, increasing disease awareness and improving diagnosis rates is critical. Conclusions: This study is the first national physician survey of WM conducted in China. It systematically describes the issues that exist in WM diagnosis and treatment in China, such as a high rate of misdiagnosis, limited access to gene testing and new drugs, and poor patient adherence to treatment. Chinese doctors believe that improving doctors' and patients' understanding of WM is one of the most urgent issues that must be addressed right now.

[Clinical and biological features and prognosis of patients with leukemic non-nodal mantle cell lymphoma].

Objective: To investigate the clinical, biological and prognostic characteristics of leukemic non-nodal mantle cell lymphoma (nnMCL). Methods: The clinical data of 14 patients with nnMCL and 238 patients with classical mantle cell lymphoma (cMCL) in Blood Diseases Hospital, Chinese Academy of Medical Sciences from November 2000 to October 2020 were retrospectively analyzed. Among the 14 patients with nnMCL, there were 9 males and 5 females, with the age [M (Q1, Q3)] of 57.5 (52.3, 67.0) years. Among the 238 patients with cMCL, there were 187 males and 51 females, with the age of 58.0 (51.0, 65.3) years. The clinical and biological characteristics of the two groups were recorded and compared. Follow-up and efficacy evaluation were conducted by re-examination during hospital stay and telephone follow-up and so on. Results: The proportion of CD200 expression in nnMCL patients was 8/14, which was higher than that in cMCL patients [14.6% (19/130)] (P=0.001). The proportion of CD23 expression in nnMCL patients was 8/14, which was higher than that in cMCL patients [13.5% (23/171)] (P<0.001). The proportion of CD5 expression in nnMCL patients was 10/14, which was lower than that in cMCL patients [97.4% (184/189)] (P=0.001). The proportion of CD38 expression in nnMCL patients was 4/14, which was lower than that in cMCL patients [69.6% (112/161)] (P=0.005). The expression proportion of sex-determining region of Y chromosome-related high-mobility-group box 11 (SOX11) in nnMCL patients was 1/5, which was lower than that in cMCL patients [77.9% (60/77)] (P=0.014). The proportion of immunoglobulin heavy chain variable region (IGHV) mutations in nnMCL patients was 11/11, which was higher than that in cMCL patients [26.0% (13/50)] (P<0.001). As of April 11, 2021, the follow-up time for nnMCL and cMCL patients was 31 (8-89) months and 48 (0-195) months, respectively. Among the 14 nnMCL patients, 6 patients were still under observation, and 8 patients were treated. The overall response rate (ORR) was 8/8, including 4 patients with complete remission and 4 patients with partial response. The median overall survival and median progression-free survival were not reached in nnMCL patients. In the cMCL group, 50.0% (112/224) patients achieved a complete response, 24.6% (55/224) patients achieved a partial response, and ORR was 74.6% (167/224). There was no statistically significant difference in ORR between the two groups (P=0.205). Conclusions: nnMCL patients have an indolent progression, with higher expression rates of CD23 and CD200 and lower expression rates of SOX11, CD5 and CD38. Most patients have IGHV mutations, with a relatively good prognosis, and"watch and wait"approach is an optional treatment.

[Analysis and prediction of thyroid cancer morbidity and mortality trends in China].

Objective: To analyze the morbidity and mortality trends of thyroid cancer in China from 1990 to 2019, explore the causes of the trends, and predict morbidity and mortality in the future. Methods: The morbidity and mortality data of thyroid cancer in China from 1990 to 2019 were collected from the 2019 Global Burden of Disease database. The Joinpoint regression model was used to describe the change trends. Based on the morbidity and mortality data from 2012 to 2019, a grey model GM (1,1) was constructed to predict the trends in the next ten years. The model was tested by the posterior error method and residual test method. Results: In all populations, men and women, the AAPC values of the crude morbidity rates were 4.15% (95%CI: 3.86%-4.44%, P<0.001), 5.98% (95%CI: 5.65%-6.31%, P<0.001) and 3.23% (95%CI: 2.94%-3.53%, P<0.001) respectively, the AAPC values of age-standardized morbidity rates were 2.47% (95%CI: 2.12%-2.83%, P<0.001), 3.98% (95%CI: 3.68%-4.29%, P<0.001), 1.65% (95%CI: 1.38%-1.93%, P<0.001), the AAPC values of crude mortality rates were 2.09% (95%CI: 1.92%-2.25%, P<0.001), 3.68% (95%CI: 3.45%-3.90%, P<0.001), 0.60% (95%CI: 0.50%-0.71%, P<0.001). The age-standardized mortality rates in men showed a fluctuating trend of first decrease (1990-1994), then increase (1994-2012), and then decrease (2012-2019) (AAPC=1.35%, 95%CI: 1.16%-1.53%, P<0.001). The age-standardized mortality rate in women continuously decreased (AAPC=-1.70%, 95%CI: -1.82%- -1.58%, P<0.001). The GM (1,1) models can be used for medium and long-term predictions. The results of the residual test show that the average relative error values of all models are less than 10.00%, the prediction accuracy values are more than 80.00%, and the prediction effects are good. The results of the posterior error method show that all the prediction results are good except the qualified prediction of the age-standardized morbidity rate in men. In 2029, the crude morbidity rates would increase to 3.57/100 000, 2.78/100 000, and 4.40/100 000, respectively, and the age-standardized incidence rates would increase to 2.38/100 000, 1.89/100 000, and 2.88/100 000, respectively, the crude mortality rates would increase to 0.57/100 000, 0.62/100 000 and 0.53/100 000, and the age-standardized mortality rates would decrease to 0.33/100 000, 0.42/100 000 and 0.27/100 000 in all population, men and women in China. Conclusions: The overall, gender- specific age-standardized mortality rates showed downward trends in the last decade or so, and the prediction results showed that it might further decline. However, the crude morbidity rates, age-standardized and crude mortality rates have been on the rise, and the population aging is becoming increasingly serious in China, which requires close attention and targeted prevention and control measures.

[Clinical and biological characteristics of non-IgM lymphoplasmacytic lymphoma].

Objective: The study aims to explore the clinical and biological characteristics of patients with non-IgM lymphoplasmacytic lymphoma (LPL) . Methods: The clinical data of 340 patients with LPL admitted to the Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College were collected retrospectively, including 23 cases of the non-IgM LPL and 317 cases of the Waldenström's macroglobulinemia (WM) , from July 1993 to August 2020. The clinical and biological characteristics of the two groups were compared. Results: Among 23 patients with the non-IgM type LPL, two patients secreted monoclonal IgA, 14 patients secreted monoclonal IgG, and seven patients did not secrete monoclonal immunoglobulin. The median age of the non-IgM LPL and WM were both 62 (35-81) years old. Compared with the WM group, the proportion of women (56.5% vs 27.3%, P=0.007) , the proportion of splenomegaly (60.1% vs 43.8%, P=0.100) , and the proportion of extranodal invasion (21.7% vs 12.3%, P=0.672) in non-IgM LPL group were higher. Eighteen patients were tested for MYD88 gene mutation, and the overall mutation rate of MYD88 was 55.6%. In the non-IgM LPL group, a total of 17 patients received treatment, which had a comparable proportion (94.4% vs 92.7%, P=0.488) to the WM group. Sixteen patients were evaluated for efficacy, and the overall remission rate of the first-line treatment was 87.5%. The median follow-up time was 33.9 (3.5-125.1) months, and the median PFS and OS were both not reached. The 3-year PFS and OS rates were 71.4% and 68.9%, respectively. In the WM group, the median PFS was 66.2 months and the median OS was 78.1 months. Compared with the WM group, in the non-IgM group no significant differences in PFS (P=0.340) and OS (P=0.544) were seen. Conclusion: The clinical and biological characteristics of the non-IgM LPL and WM patients were similar. However, the proportion of women and extranodal involvement were higher in the non-IgM LPL group. The survival and prognosis of the non-IgM LPL patients were similar to those of the WM patients.

[Analysis of screening results and risk factors of high-risk populations of lung cancer in Nanchang city from 2018 to 2019].

Objective: To collate and analyze the screening results of high-risk lung cancer populations in communities in Nanchang from 2018 to 2019, and to explore the lung-positive nodules and risk factors for lung cancer. Methods: Data of the screening subjects in 8 administrative districts and 15 street health service centers in Nanchang city, Jiangxi province from November 2018 to October 2019 were collected, people at high risk of lung cancer was assessed, clinical screening of high-risk groups of lung cancer was conducted by low-dose helical computed tomography (LDCT), and risk factors for suspected lung cancer and lung-positive nodules were analyzed. Results: Of the 25 871 people participated in screening, 5 220 were at high risk for lung cancer and 15 374 without other malignant tumors were at high risk. There were 2 417 cases participated in clinical LDCT screening, including 193 cases of lung-positive nodules, 67 cases of suspected lung cancer, 912 cases of other lung diseases, the positive rate of lung cancer or lung-positive nodules was 10.76% (260/2 417). Univariate analysis showed that age, coarse grain intake, oil intake, housing heating, passive smoking, alcohol consumption and mental trauma were associated with positive pulmonary nodules or lung cancer (all P<0.05). Multivariate analysis showed that gender, age, housing heating, smoking and drinking were related to the occurrence of lung nodules or lung cancer (all P<0.05). Conclusions: Men are more likely to develop lung cancer or lung-positive nodules than women. The age is an independent risk factor for lung-positive nodules or lung cancer. In a certain range, age will increase the incidence of lung cancer, housing heating may be the protective factor for lung cancer, while smoking and drinking are risk factors.

[The association between myopic refraction and near work among children and adolescents based on genetic risk score].

Objective: To explore the relationship between myopic refraction and near work in children and adolescents with different genetic risks. Methods: From September to December 2016, Nankai District and Hongqiao District of Tianjin were taken as the study sites. Using the method of stratified cluster random sampling, 533 children and adolescents aged 6-14 years from one primary school and one junior middle school in each of the two districts were included as the study subjects. Refraction measurements by an auto-kerato-refractor and questionnaire survey about near work were conducted. 11 single nucleotide polymorphisms in the selected myopia susceptibility genes were detected, and the genetic risk of each individual was scored. After grouping by genetic risk score, the relationship between myopia and near work was analyzed by the multivariate logistic regression, and the relationship between near work and refraction was analyzed by the multivariate linear regression. Results: The age of 553 subjects was (9.8±2.5) years, including 295 boys (53.3%). The overall detection rate of myopia was 62.0%. The spherical equivalent refraction (SER) was (-1.30±1.85) D. The results of the multivariate logistic regression showed that in the low risk group of GRS, compared with those with continuous near work time less than half an hour, those with continuous near work time no less than half an hour had a higher risk of myopia [OR (95%CI) = 2.64 (1.07, 6.52)]. In the moderate risk group of GRS, the risk of myopia increased with the increase of daily computer use [OR (95%CI) = 2.14 (1.03, 4.77)]. In the high risk group of GRS, the risk of myopia increased with the increase of the total daily reading and writing time [OR (95%CI) = 1.27 (1.01, 1.59)]. The results of the multivariate linear regression showed that in the low risk group of GRS, with increase of 1 hour in the total daily reading and writing time and mobile phone time, the SER decreased by 0.18 D (95%CI:-0.30, -0.07) and 0.95 D (95%CI:-1.51, -0.39), respectively. In the moderate risk group of GRS, with increase of 1 hour in the total daily reading and writing time and computer use time, the SER decreased by 0.25 D (95%CI:-0.31, -0.18) and 0.57 D (95%CI:-0.97, -0.18), respectively. In the high risk group of GRS, with increase of 1 hour in the daily total reading and writing time, the SER decreased by 0.33 D (95%CI:-0.43, -0.22). Conclusion: Continuous near work time no less than half an hour, daily computer use time, the total daily reading and writing time, and daily mobile phone use time were associated with myopic refraction in children and adolescents.

[Clinical analysis of 70 chronic lymphocytic leukemia patients with trisomy 12 detected by FISH].

Objective: To summarize and investigate the characteristics, prognosis and treatments of chronic lymphocytic leukemia (CLL) patients with trisomy 12 by using FISH (CEP12). Methods: Clinical data of 330 CLL patients were analyzed retrospectively by using FISH (CEP12) to detect trisomy 12 from May 2003 to April 2015. The clinical data and laboratory characteristics of CEP12 positive patients (70 cases) were compared with those CEP12 negative patients (260 cases). Results: Compared with CEP12 negative CLL patients, the proportion of hepatomegaly (13.6% vs 4.0%, P=0.011) and LDH>247 U/L (43.3% vs 18.5%, χ(2)=15.892, P<0.001) in CEP12 positive CLL patients were much higher, respectively. There were no significant differences between age, sex, clinical stage, ß(2)-microglobulin level, IGHV mutation ratio and splenomegaly/lymphadenopathy in these two subgroups. However, compared with CEP12 negative patients, CEP12 positive patients had higher ratio of FMC7 (23.8% vs 12.7%, χ(2)=4.730, P=0.030), and lower ratio of CD23 (95.2% vs 99.6%, P=0.033). The overall response rates (ORR) in Fludarabine (without Rituximab), Rituximab (with or without Fludarabine) and the traditional chemotherapy group (chlorambucil, CHOP or CHOP-like) were 77.5% (31/40), 84.8% (56/66) and 45.4% (50/110), respectively. The ORR of the traditional chemotherapy group was lower than that of the Fludarabine group and Rituximab group. For CEP12 positive patients, the ORR was inferior to CEP12 negative patients when only using Fludarabine (P<0.05). However, when using Rituximab, the difference could be eliminated, and the ORR was even a little higher in CEP12 negative patients (91.7% vs 81.0%, P=0.306). Compared with CEP12 negative patients, there were no significant differences in progression-free survival (PFS) (χ(2)=0.410, P=0.478) and overall survival (OS) (χ(2)=0.052, P=0.180) for CEP12 positive patients whom the median time from diagnosis to start treatment and OS time was 22.6 (95%CI 15.4-31.7) and 118.5 (95%CI 74.5-162.4) month while the 5-year PFS and OS were (52.9±7.6)% and (74.8±6.6)%. Conclusions: CEP12 positive CLL patients are more common in hepatomegaly and higher level of LDH. The traditional chemotherapy treatment had the lowest efficacy, and the curative effect of single use of fludarabine is not as good as that of CEP12 negative patients, however, when using Ritaximab, the efficacy could be comparable.

[IGHV mutational statue in patients with splenic marginal zone lymphoma].

Objective: To investigate the IGHV mutational status and its differences from Caucasian in splenic marginal zone lymphoma (SMZL). Methods: A retrospective study on 40 SMZL cases were performed to detect the V-D-J sequence of IGHV by plasmid cloning sequencing, comparing the data with the most homologous germ line V sequence in database, identifying the stereotype of patients through cluster analysis and alignment. The clinical and laboratory characteristics were compared between the patients with IGHV mutation and without mutations. Results: In SMZL patients, the proportion of IGHV mutations was 75%, consistent with data from Caucasian. In V region, the usage of V3-23 subtype was lower in Chinese patients compared with Caucasian (2.6% vs 18.0%, P=0.006), whereas the V2-70 subtype was used with high proportion (10.3% vs 0.8%, P=0.002). In D region, the D2-21 and D6-13 gene were used frequently (17.9% vs 2.3%, P<0.001; 12.8% vs 3.8%, P=0.046). One new stereotype was found, and the SMZL-biased V1-2 gene was mostly used (25.6%). The levels of IgG and IgA were significantly increased in IGHV without mutations as compared with mutations [10.70 (5.28-15.50) g/L vs 12.90 (7.71-23.50) g/L, 1.06 (0.21-3.13) g/L vs 1.66 (0.81-2.93) g/L, P=0.038, 0.040]. The only two 17p deletion patients were IGHV without mutaions. The progression free survival (PFS) was significantly prolonged in IGHV mutations (P=0.009), and there was no significant difference regarding to the overall survival between the two subgroups (P=0.430). Conclusion: The proportion of IGHV mutaions was similar to the data in Caucasian. There was disparity in the usage of V and D regions between Chinese and Caucasian, and the SMZL-biased V1-2 gene were used more frequently in Chinese patients. One new stereotype was identified. In the IGHV without mutations group, the levels of IgG and IgA were significantly increased.

[Study on puji ointment in treating 628 cases with second and third-degree burns and its decrustative effect].

The treatment of second and third-degree burns in small range with Puji ointment (PJO) application showed an obvious advantage over conventional medicine in ceasing exudate, antihydropism and decrustation (P < 0.01). Experiments on rabbits with third-degree burns treated by PJO with vaseline gauze as control revealed that the pH of the tested animal group became neutral more quickly than the control group, and the same as the healing of burns (P < 0.01). PJO application was found to be markedly effective in reducing exudate, antihydropism, preventing infection and speeding up healing. It also demonstrated that the specific decrustative function existed on third-degree burns in small size.

Locating a low density lipoprotein-targeting domain of human apolipoprotein B-100 by expressing a minigene construct in transgenic mice.

Through its interaction with the low density lipoprotein (LDL) receptor, apolipoprotein (apo) B-100 is a major determinant of LDL metabolism and plasma cholesterol. Its receptor binding ability is conformation-dependent and requires its expression on the right lipoprotein particles. The structural signal that targets apoB-100 to LDL is unknown. We have microinjected a human apoB-100 minigene construct comprising less than 25% of the apoB-100 sequence driven by the natural apoB promoter to produce transgenic mice. The transgene product was expressed at a high level and was present exclusively in the LDL of these animals. Analysis of the responsible sequence (residues 2878-3925 of apoB-100) reveals unique structural features that may be important in its role as an LDL-targeting domain.

Apolipoprotein B mRNA editing is an intranuclear event that occurs posttranscriptionally coincident with splicing and polyadenylation.

The subcellular compartment in which apolipoprotein (apo) B mRNA is edited is unknown. We studied the site of endogenous apoB mRNA editing and correlated the extent of editing with mRNA maturation in the rat liver. RNA editing activity was demonstrated in both nuclear and cytoplasmic extracts. The specific activity of the editing activity was 5.5-fold higher in the nuclear extract, which was not accounted for by activators, inhibitors, or modulators. However, the total editing activity was 3.1 times higher in the cytoplasmic extract. Highly purified rat liver nuclear apoB mRNA contained 17.3 +/- 1.45% edited sequences compared with 56 +/- 2.5% and 62.15 +/- 6.2% edited sequences in hepatic total and polysomal RNAs, respectively. Because of the significant extent of editing of total nuclear RNA, we fractionated it into a poly(A-) and poly(A+) fraction. While the poly(A-) nuclear fraction contained only 10.4 +/- 1.1% edited sequences, which represents a maximum estimate, the poly(A+) nuclear apoB mRNA contained 50 +/- 1.8% edited sequences, a value very similar to that for polysomal RNA. By direct sequencing of cDNA and genomic clones, we found that as in the case of the human apoB gene, the rat apoB gene contains an intron 25 immediately upstream of the edited exon 26. Using this information, we developed a method to examine in a highly selective manner apoB mRNA that is present in the nucleus before splicing of intron 25 and after splicing of this intron. The unspliced nuclear pre-mRNA contained 7.4 +/- 0.2% edited sequences compared with 51.0 +/- 0.9% edited sequences in the spliced nuclear apoB mRNA. Furthermore, in the poly(A-) pool of apoB pre-mRNA, unspliced nuclear pre-mRNA contained hardly any (1.56%) edited sequences, and the spliced nuclear pre-mRNA contained 7.8 +/- 0.6% edited mRNA. In the poly(A+) fraction, unspliced nuclear pre-mRNA had 25.4 +/- 0.05% and spliced nuclear mRNA 53 +/- 0.6% of its apoB mRNA in an edited form. We conclude that in the rat liver apoB mRNA editing is not a cotransciptional event. It occurs posttranscriptionally, but the process is essentially complete in the spliced polyadenylated apoB mRNA before it leaves the nucleus. Little, if any, additional editing occurs in the cytoplasmic compartment.

No severe bottleneck during human evolution: evidence from two apolipoprotein C-II deficiency alleles.

The DNA sequences of a Japanese and a Venezuelan apolipoprotein (apo) C-II deficiency allele, of a normal Japanese apo C-II gene, and of a chimpanzee apo C-II gene were amplified by PCR, and their nucleotide sequences were determined on multiple clones of the PCR products. The normal Japanese sequence is identical to--and the chimpanzee sequence differs by only three nucleotides from--a previously published normal Caucasian sequence. In contrast, the two human mutant sequences each differ from the normal apo C-II gene sequence by several nucleotides, including deletions. The data suggest that both mutant alleles arose greater than 500,000 years ago. It is shown that a defective allele can persist in a population for only a short time if a bottleneck occurs. Therefore, the antiquity of the two alleles suggests no severe bottleneck during human evolution. Moreover, the fact that one allele is from Japan and the other is from a Venezuelan Caucasian family is more consistent with the multiregional evolution model of modern human origins than with the complete replacement or "out of Africa" model.

Determination of the complete nucleotide sequence of HBV adr NC-1 DNA.

On the basis of sequencing the large DNA-fragments which have been inserted into M13mp8, we design a simple strategy to determine the complete nucleotide sequence of HBV adr NC-1 DNA with chain termination method. The whole genome is 3195 nucleotides long. Five reading frames are observed. The gene location and organization are shown.

The primary structure of human apolipoprotein A-IV.

Human apolipoprotein (apo) A-IV was purified from chylous ascites fluid. Proteolytic peptides produced by trypsin and Staphylococcus aureus V8 proteinase digestions were purified by high-performance liquid chromatography and sequenced. Human apoA-IV contains 376 amino acid residues. The peptide-derived sequence generally matches two previously reported DNA-derived amino acid sequences except for discrepancies in five positions. In order to examine these discrepancies further, one complete apoA-IV cDNA clone and another partial clone were sequenced. Comparison of all the available information indicates that the peptide-derived sequence reported here is accurate. Sequencing errors probably account for some of the discrepancies between the two primary sequences predicted by earlier nucleotide analyses. In certain positions, however, bona fide sequence heterogeneity or cloning artifact cannot be excluded.

Rapid typing of tandemly repeated hypervariable loci by the polymerase chain reaction: application to the apolipoprotein B 3' hypervariable region.

The 3' flanking region of the apolipoprotein B (apoB) gene contains a hypervariable region consisting of a variable number of tandemly repeated short A + T-rich DNA sequences (VNTRs). We present a general method that utilizes the polymerase chain reaction to rapidly and accurately type this and other VNTR loci. We use tailored oligonucleotides and thermostable Taq polymerase to amplify the targeted region. The amplification products are directly visualized after agarose gel electrophoresis. Twelve alleles were readily identified in a sample of 125 unrelated individuals. The alleles differ with respect to the length of the amplified gene region. This genetic variability is inherited in an autosomal codominant manner. DNA sequence data indicate that individual alleles differ in the number of repeat units and the sensitivity of the technique is such that alleles differing in length by only 32 base pairs are readily distinguishable. A system of nomenclature based on the number of repeat units is suggested; an allele containing 37 repeat units is designated 3' beta 37, one containing 35 units is 3' beta 35, and so on. The frequency distribution of the 12 apoB VNTR alleles is bimodal with peaks at 37 and 47 repeat units and a nadir near 43 repeat units. We estimate that the 3' apoB VNTR locus has a heterozygosity index of 0.75 and a polymorphic information content of 0.73. It is a highly informative marker for genetic linkage studies on chromosome 2 and clinical and epidemiological studies involving the apoB gene. The high sensitivity and inexpensive nature of this technique make it superior to traditional Southern blot analysis for typing the 3' apoB VNTR. The method described is also directly applicable for rapid typing of other VNTRs in the human genome.