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Objective: To determine whether detection of small mutations of the dystrophin gene can be increased using an enhanced method of single-strand conformation polymorphism analysis. Background: Usual methods of DNA analysis for Duchenne dystrophy cannot identify mutations in one-third of cases. Muscle biopsy, with its inherent risks and added liability for patients with Duchenne dystrophy, becomes the sole method of diagnosis. Even with a tissue diagnosis of dystrophin deficiency, many families are excluded from carrier detection and prenatal diagnosis. Methods: Genomic DNA from a cohort of 93 patients with Duchenne dystrophy without identifiable gene mutations was screened for mutations. In each case, 22 kilobases of genomic DNA were scanned, including all 79 exons of the dystrophin gene, adjacent intronic regions, and six alternative exons 1. Results: Sixty-eight (73%) had small mutations, including 34 nonsense mutations, 27 microdeletions and insertions, and 7 splice site mutations. No missense mutations were found. One nonsense mutation in exon 59 was detected in four patients. Most mutations were new; 54 of 62 different small mutations have not been reported. Mutations were found throughout the gene: 24% in the first quartile, 31% in the second, 16% in the third, and 29% in the fourth. Conclusions: A highly sensitive single-strand conformation polymorphism method substantially increased detection of small dystrophin gene mutations and made it possible to diagnose approximately 90% of patients with Duchenne dystrophy by DNA analysis. These findings, combined with cost savings and safety issues, provide compelling reasons to consider DNA analysis as the initial diagnostic test for the suspected dystrophin-deficient patient.

By use of cDNA probes, molecular deletions were identified in 66.6% of 42 patients with Duchenne muscular dystrophy (DMD) or Becker muscular dystrophy (BMD). Owing to this high deletion rate, a new strategy for detecting DMD/BMD carriers is feasible in which the polymerase chain reaction is used as an initial screen for detecting the deletions occurring in specific deletion-prone exons. Because the deletions do not occur randomly, specific cDNA probes are utilized first with Southern blot analysis. Identification of a deletion permits direct analysis for DMD carrier status and removes the inherent limitations of the conventional restriction fragment length polymorphism technique. Carrier status is determined by scanning the autoradiographs with a densitometric spectrophotometer or by detection of a junction fragment.

Hereditary non-polyposis colorectal cancer is characterized by mutations in one of the DNA mismatch repair genes, primarily MLH1, MSH2, or MSH6. We report here the identification of a genomic deletion of approximately 11.4 kb encompassing the first two exons of the MSH2 gene in two generations of an Ohio family. By Southern blot analysis, using a cDNA probe spanning the first seven exons of MSH2, an alteration in each of three different enzyme digests (including a unique 13-kb band on HindIII digests) was observed, which suggested the presence of a large alteration in the 5' region of this gene. Mouse-human cell hybrids from a mutation carrier were then generated which contained a single copy each of human chromosome 2 on which the MSH2 gene resides. Southern blots on DNA from the cell hybrids demonstrated the same, unique 13-kb band from one MSH2 allele, as seen in the diploid DNA. DNA from this same monosomal cell hybrid failed to amplify in polymerase chain reactions (PCRs) using primers to exons 1 and 2, demonstrating the deletion of these sequences in one MSH2 allele, and the breakpoints involving Alu repeats were identified by PCR amplification and sequence analysis.

Diffuse uterine leiomyomatosis is a rare condition distinguished from the common uterine leiomyomata by involvement of the entire myometrium by innumerable, ill-defined, often small and confluent, histologically benign smooth-muscle nodules. Fourteen cases have been previously described in the literature. We report a case of diffuse leiomyomatosis in a 39-year-old woman. Several microscopic foci of the process were microdissected for clonality analysis. All samples showed a non-random X-chromosome inactivation pattern, and thus were consistent with a monoclonal neoplastic population of cells. However, in different foci of tumor, different X chromosomes were inactivated, supporting the independent origin of neoplastic clones and rejecting the possibility of a single clonal origin of all tumor cells. The results of the molecular analysis suggest that diffuse uterine leiomyomatosis may be an exuberant example of diffuse and uniform involvement of the entire myometrium by multiple leiomyomata. HUM PATHOL 31:1429-1432.

Transfusion-associated graft-vs-host disease (TA-GVHD) is a rare complication of transfusion. We report fatal TA-GVHD in a 63-year-old coronary artery bypass patient of European descent after an RBC transfusion from an unrelated donor. The patient had mild lymphocytopenia and received 2 80-mg doses of methylprednisolone and 7 units of RBCs. On day 14 after the transfusion, he had fever, elevated liver enzyme levels, and a macular rash. Pancytopenia and bone marrow aplasia developed. On day 26, he had a massive gastrointestinal hemorrhage and died. At autopsy, histopathologic findings of the skin, liver, bone marrow, and gastrointestinal tract were consistent with TA-GVHD. One donor of the transfused RBCs (3 days old at transfusion) had a 1-way HLA match with the patient. A method using multiplex polymerase chain reaction is presented. This patient with TA-GVHD and mild immune suppression suggests that blood component irradiation guidelines may need to be reevaluated.

PMS2 is one of a complex of genes encoding DNA repair proteins that includes MSH2, MLH1, MSH6 and MSH3. Mutation of any of these DNA mismatch repair genes leads to impairment of DNA repair and can lead to tumorigenesis. Germline mutation of PMS2 has been reported as a rare cause of hereditary nonpolyposis colorectal cancer (HNPCC) and Turcot's syndrome. The PMS2 gene is located on chromosome 7p22 and consists of 15 exons. Within exon 11 of PMS2 is a coding repeat of eight adenosines. This study reports on the finding of a nonexpressed pseudogene that is highly homologous to the PMS2 gene in this region. The pseudogene is polymorphic for two alterations in the repeat region: a 3 bp delAAA at a site corresponding to nucleotide 1231 in PMS2; and an AA--GG change at nucleotide 1238. Due to the high homology in both intronic and exonic sequences, polymorphisms in this pseudogene could be mistaken for mutations in the PMS2 gene and erroneously thought to be a cause of HNPCC and/or Turcot's syndrome.

A single report of brothers born to first-cousin parents with a form of acute spinal muscular atrophy (SMA) and congenital fractures suggested that this combination represented a distinct form of autosomal recessive SMA. We describe a boy with hypotonia and congenital fractures whose sural nerve and muscle biopsies were consistent with a form of spinal muscular atrophy. Molecular studies identified no abnormality of the SMN(T) gene on chromosome 5. This case serves to validate the suggestion of a distinct and rare form of spinal muscular atrophy while not excluding possible X-linked inheritance.

Gastrinomas and other gastrointestinal neuroendocrine tumors may occur sporadically or as part of the inherited syndrome multiple endocrine neoplasia type 1 (MEN1). Mutations in the recently identified MEN1 gene have been described in sporadic gastrinomas and insulinomas. This study describes techniques used to identify mutations in the MEN1 gene in DNA extracted from paraffin-preserved tissue. Two novel mutations are identified in the MEN1 gene from nine archived paraffin-embedded neuroendocrine tumors, demonstrating that retrospective genetic analysis can be used to identify mutations in the MEN1 gene from preserved tissue. Conditions are provided by which paraffin-embedded tissue can be used as a source of genetic material for sequence information of sufficient quality for mutational studies of the MEN1 gene. It should also be possible to apply this retrospective genetic analysis of paraffin-embedded tissue to other disease models.

Approximately 95% of all Friedreich's ataxia (FA) patients are homozygous for a large GAA triplet-repeat expansion in the first intron of the Friedreich's ataxia gene (FRDA). The remaining cases are expected to be compound heterozygous with a GAA expansion on one allele and a point mutation on the other. Generally, the clinical diagnostic profile in this group of patients is indistinguishable from that in classic FA patients with homozygous expansions. This study describes a mildly affected patient who presents with only one expanded allele by Southern blot analysis. Point mutation screening shows a single base change in FRDA exon 3 resulting in a nonconservative amino acid replacement in the N-terminal portion of the frataxin protein. Extended family studies show that two of the patient's sibs are carriers of the expanded allele and one is a carrier of the missense mutation. This case study demonstrates the benefits of implementing a combined Southern blot and point mutation diagnostic protocol for compound heterozygous patients. By identifying both mutations, this procedure confirms the diagnosis of FA in patients with an atypical disease course and allows for more complete family studies.

Hereditary hemochromatosis, a common autosomal recessive trait caused by mutations in the HLA-H gene, is often diagnosed by the pathologist at the time of histologic examination. Unfortunately, histologic parameters alone do not differentiate between hereditary hemochromatosis and other causes of iron overload. We performed a retrospective study to determine the frequency of familial hemochromatosis in patients diagnosed with he mochromatosis by abnormal liver histology.DNA was isolated from paraffin-embedded tissue sections from 15 patients and used in a polymerase chain reaction-based assay in which we tested for the C282Y and H63D mutations. We found that in this group of patients, 5 (33%) were homozygous for the common C282Y genetic mutation, 3 (20%) were heterozygous, and 7 (47%) were normal.Our study shows that the molecular assay is the gold standard for the diagnosis of hereditary hemochromatosis. The case study also illustrates that a definitive diagnosis of familial hemochromatosis has significant counseling implications allowing for accurate family studies.

The main goal of this study was to examine the vestibular ganglia from 11 patients with intractable classic Menière's disease (MD) for the presence or absence of DNA from three neurotropic viruses (herpes simplex virus, cytomegalovirus, and varicella zoster virus) using exquisitely sensitive molecular biologic techniques.This was a prospective controlled study with vestibular ganglia from patients with MD and from patients with small vestibular schwannomas undergoing resection. Polymerase chain reaction was used for viral DNA detection from the ganglia along with known positive and negative polymerase chain reaction control subjects.The study was performed in an academic tertiary referral center.Patients for inclusion had medically uncontrolled MD, including documented fluctuating sensorineural hearing loss, episodic vertigo, and tinnitus who elected to undergo vestibular nerve section. Control patients were undergoing vestibular schwannoma removal.The intervention was vestibular nerve section with removal of vestibular ganglion.The presence or absence of viral DNA (herpes simplex virus, cytomegalovirus, and varicella zoster virus) in vestibular ganglion tissues detected by polymerase chain reaction.No viral DNA was detected in the vestibular ganglia of patients with MD (p = 0.028) nor in the control group. The likelihood of a type II or beta type error was10%.In patients with MD requiring surgical intervention, infection with herpes simplex virus, cytomegalovirus, or varicella zoster virus of the vestibular ganglia does not appear to play a major role in the pathoetiology of the disease.

Molecular genetic understanding of Duchenne and Becker muscular dystrophies has unfolded rapidly in the past decade. The new molecular understanding has enhanced diagnosis, prognosis, carrier detection, and prenatal diagnosis. Most importantly, strategies are being devised currently for the treatment of the disorder. This article provides an update on the molecular findings and their applicability in clinical practice.

Duchenne and Becker muscular dystrophies (DMD and BMD) are caused by defects in the dystrophin gene. About two-thirds of the affected patients have large deletions or duplications, which occur in the 5' and central portion of the gene. The nondeletion/duplication cases are most likely the result of smaller mutations that cannot be identified by current diagnostic screening strategies. We screened approximately 80% of the dystrophin coding sequence for small mutations in 158 patients without deletions or duplications and identified 29 mutations. The study indicates that many of the DMD and the majority of the BMD small mutations lie in noncoding regions of the gene. All of the mutations identified were unique to single patients, and most of the mutations resulted in protein truncation. We did not find a clustering of small mutations similar to the deletion distribution but found > 40% of the small mutations 3' of exon 55. The extent of protein truncation caused by the 3' mutations did not determine the phenotype, since even the exon 76 nonsense mutation resulted in the severe DMD phenotype. Our study confirms that the dystrophin gene is subject to a high rate of mutation in CpG sequences. As a consequence of not finding any hotspots or prevalent small mutations, we conclude that it is presently not possible to perform direct carrier and prenatal diagnostics for many families without deletions or duplications.

Myotonic dystrophy (DM) is an autosomal dominant genetic disease caused by an unstable CTG repeat sequence in the 3' untranslated region of the myotonin protein kinase gene. The CTG repeat is present 5-30 times in the normal population, whereas DM patients have CTG expansions of 50 to several thousand repeats. The age of onset of the disorder and the severity of the phenotype is roughly correlated with the size of the CTG expansion. We developed a molecular protocol for the diagnosis of DM based on an initial polymerase chain reaction screen to detect normal-sized alleles and small expansions, followed by an improved Southern protocol to detect larger expansions.

Duchenne muscular dystrophy (DMD) patients with mutations that disrupt the translational reading frame produce little or no dystrophin. Two exceptions are the deletion of exons 3-7 and the occurrence of rare dystrophin-positive fibers (revertant fibers) in muscle of DMD patients. Antibodies directed against the amino-terminus and the 5' end of exon 8 did not detect dystrophin in muscle from patients who have a deletion of exons 3-7. However, in all cases, dystrophin was detected with an antibody directed against the 3' end of exon 8. The most likely method of dystrophin production in these cases is initiation at a new start codon in exon 8. We also studied two patients who have revertant fibers: one had an inherited duplication of exons 5-7, which, on immunostaining, showed two types of revertant fibers; and the second patient had a 2-bp nonsense mutation in exon 51, which creates a cryptic splice site. An in-frame mRNA that uses this splice site in exon 51 was detected. Immunostaining demonstrated the presence of the 3' end of exon 51, which is in agreement with the use of this mRNA in revertant fibers. The most likely method of dystrophin production in these fibers is a second mutation that restores the reading frame.

Neurotropic viruses have been postulated to play a role in the development of Menière's disease (MD). The purpose of this study was to evaluate the endolymphatic sacs of patients undergoing surgery for MD in a single-blind study for evidence of herpes simplex virus (HSV), varicella zoster (VZ), or cytomegalovirus (CMV) DNA. Polymerase chain reaction (PCR) was used as the method of detection because of its sensitivity, specificity, and applicability to fresh, as well as fixed tissues. Twenty-two patients with MD and 11 control patients with vestibular schwannomas had a portion of the endolymphatic sac removed at the time of surgery. The specimens were then evaluated for herpes simplex type and 2, varicella zoster, and cytomegalovirus DNA. Herpes simplex virus DNA was detected in 2 of the 22 extracts from the endolymphatic sacs obtained from patients with MD. There was no evidence of a positive signal obtained with any of the other viral DNA probes when PCR was performed on the control tissue extracts or the other MD tissue extracts. These results do not demonstrate a significant difference and do not statistically support the postulate that ongoing viral infection in the endolymphatic sac is a frequent factor in the development of Menière's disease.

The polymerase chain reaction was used to detect cytomegalovirus (CMV) in 91 formalin-fixed paraffin-embedded needle biopsies from 38 liver transplant patients with allograft dysfunction. Thirty donor liver biopsies served as negative controls. PCR results were compared with light microscopy (LM), immunohistochemical staining (IH) for CMV early and late antigen, and clinical data. Primers to the major immediate early gene (MIE) and the viral DNA polymerase gene were duplex amplified. PCR product was reamplified with a nested primer set for the MIE and confirmed by electrophoretic mobilities and dot blotting. Primers for human beta-hemoglobin were used as internal controls. Seventeen of 38 patients had clinical evidence of cytomegalovirus disease, 12 of these were IH-positive, 14 were LM-positive, 15 were duplex PCR-positive and 17 were nested PCR-positive. In addition, duplex PCR was positive in one patient without other evidence of CMV disease, while nested PCR was positive in 12 such patients. The sensitivity and negative predictive value of nested PCR was 100%--however, the specificities and positive predictive values were only 42.9 and 58.6%, respectively. The control group was completely negative by LM, IH, and duplex PCR, however, 6 of 30 patients were nested PCR-positive. The number of nested-positive, duplex-negative patients without CMV disease was significantly greater in the transplant group versus the control group (12/21 vs. 6/30, P0.009). The incidence of IgG seropositivity was also significantly greater in the transplant group versus the controls (29/32 vs. 15/24, P0.02). We conclude that nested PCR may be an overly sensitive technique for the detection of clinically relevant CMV disease. A negative nested PCR assay for CMV may, however, help rule-out symptomatic CMV infection in an individual case. Duplex PCR showed little advantage over LM, while IH was confirmatory but did not add any new information in this study.

It has been postulated that celiac disease (CD) is initiated by adenovirus 12 infection (1). To test this hypothesis, we devised a PCR-based strategy to simultaneously screen for adenovirus 12 (Ad12), cytomegalovirus (CMV), and herpes simplex viruses (HSV) 1 and 2 in formalin-fixed paraffin-embedded small bowel biopsies from adult and childhood CD patients. Control groups consisted of small bowel biopsies from normal adults and children, adults with active peptic duodenitis, and children with active duodenitis. Ad12 DNA was found in two of 19 adult CD biopsies (two of 14 patients), while CMV and HSV DNA was found in one of the 19 adult CD biopsies. Ad12 and CMV DNA was not present in 19 child CD biopsies, while HSV DNA was found in two of these same biopsies. CMV and HSV DNA were not found in any of the control group patients. Ad12, CMV, and HSV DNA were not identified in significant numbers in any patient group. These findings argue against the presence of persistent adenovirus infection in CD patients but do not preclude remote Ad12 infection prior to the onset of CD. Similarly, the absence of CMV and HSV DNA in CD, active peptic disease in adults, and active duodenitis in children suggests that neither virus is involved in the persistence of these inflammatory conditions.

Molecular biology techniques have changed the way in which we now consider a patient with Duchenne muscular dystrophy or Becker muscular dystrophy. Using cDNA probes, it has been shown that approximately 65% of the patients with Duchenne muscular dystrophy or Becker muscular dystrophy have gene deletions. The identification of a deletion allows the disease to be confirmed by noninvasive DNA testing. Furthermore, the identification of the gene defect can help distinguish Becker muscular dystrophy from other clinically similar neuromuscular disorders. Most importantly, the elucidation of the gene defects has resulted in the application of direct carrier and prenatal diagnostics.

In 50 gravidas with insulin-dependent diabetes mellitus, mean preprandial whole blood glucose levels over a two-week period were compared with serum glycosylated hemoglobin (HbA1c) and fructosamine values. Although there was a statistically significant correlation between mean glucose levels and both HbA1c (r = .44, P less than .01) and fructosamine (r = .37, P less than .01), the wide range of HbA1c and fructosamine observed at all levels of mean blood glucose limited the usefulness of those assays in the management of pregnant diabetics.

Detection of carriers of Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD), in the deletion cases, involves calculating gene dosage from Southern blots. We show that the analysis of dosage can also be made from the polymerase chain reaction (PCR) with use of allele-specific oligonucleotides (ASOs). The deletion-prone exons are amplified, transferred to a membrane, and hybridized with ASOs complementary to the exons; the autoradiographic bands are then quantified with a densitometer. After determining the quantitative conditions of the amplification reaction, we were able to identify deletions in a DMD/BMD carrier female. The determination of carrier status via PCR removes several of the technical limitations of Southern analysis and is also cost- and labor-effective.

Gene mutations responsible for the majority of Duchenne/Becker muscular dystrophy (DMD/BMD) and cystic fibrosis (CF) chromosomes have been identified. We describe a DNA-based strategy, rather than the traditional biochemical assays, for screening newborns. DNA sequences spanning the CF mutation and several DMD/BMD deletion-prone exons are amplified simultaneously via a multiplex polymerase chain reaction. The gel is visually inspected for DMD/BMD deletions and then blotted and hybridized with allele-specific oligonucleotides to determine the presence or absence of the CF mutation. We determined that blood spots provide sufficient DNA for the molecular analysis, so the procedure can be used in screening programs of newborns.

By use of cDNA probes, molecular deletions were identified in 66.6% of 42 patients with Duchenne muscular dystrophy (DMD) or Becker muscular dystrophy (BMD). Owing to this high deletion rate, a new strategy for detecting DMD/BMD carriers is feasible in which the polymerase chain reaction is used as an initial screen for detecting the deletions occurring in specific deletion-prone exons. Because the deletions do not occur randomly, specific cDNA probes are utilized first with Southern blot analysis. Identification of a deletion permits direct analysis for DMD carrier status and removes the inherent limitations of the conventional restriction fragment length polymorphism technique. Carrier status is determined by scanning the autoradiographs with a densitometric spectrophotometer or by detection of a junction fragment.

Proximal spinal muscular atrophy (SMA) is a common motor neuron disease in humans and in its most severe form causes death by the age of 2 years. It is caused by defects in the telomeric survival motor neuron gene ( SMN1 ), but patients retain at least one copy of a highly homologous gene, centromeric SMN ( SMN2 ). Mice possess only one survival motor neuron gene ( Smn ) whose loss is embryonic lethal. Therefore, to obtain a mouse model of SMA we created transgenic mice that express human SMN2 and mated these onto the null Smn (-/-)background. We show that Smn (-/-); SMN2 mice carrying one or two copies of the transgene have normal numbers of motor neurons at birth, but vastly reduced numbers by postnatal day 5, and subsequently die. This closely resembles a severe type I SMA phenotype in humans and is the first report of an animal model of the disease. Eight copies of the transgene rescues this phenotype in the mice indicating that phenotypic severity can be modulated by SMN2 copy number. These results show that SMA is caused by insufficient SMN production by the SMN2 gene and that increased expression of the SMN2 gene may provide a strategy for treating SMA patients.

Detection of Duchenne muscular dystrophy carriers by genetic analysis is illustrated by four case studies. The technique is most useful in obligate families, in excluding carrier status in isolated cases, and in families in which the affected child demonstrates a molecular deletion. A major limitation of this technique is that the accuracy of carrier status in isolated (i.e., no family history) cases is limited by the probability that the affected child may represent a new mutation. To improve the carrier risk estimate generated by the DNA data, particularly in isolated cases, we suggest that measuring creatine kinase activities in the serum and performing the genetic analysis on the nonaffected males may be helpful.

Detection of Duchenne muscular dystrophy carriers by genetic analysis is illustrated by four case studies. The technique is most useful in obligate families, in excluding carrier status in isolated cases, and in families in which the affected child demonstrates a molecular deletion. A major limitation of this technique is that the accuracy of carrier status in isolated (i.e., no family history) cases is limited by the probability that the affected child may represent a new mutation. To improve the carrier risk estimate generated by the DNA data, particularly in isolated cases, we suggest that measuring creatine kinase activities in the serum and performing the genetic analysis on the nonaffected males may be helpful.