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Biomedical subjects

R Yee

Publications and source records attributed to R Yee.

At least 73 records · Page 4Linked to original sources
PubMed1997

Progressive anterior ablation in the coronary sinus region: evidence to support the presence of a 'slow pathway' input in normal patients?

BACKGROUND: AV node modification is an emerging approach to rate control in patients with medically refractory atrial fibrillation. The mechanism of benefit of this procedure is not completely understood. METHODS AND RESULTS: Twenty-two patients (age, 65+/-11 years; 16 women) with medically refractory paroxysmal atrial fibrillation referred for complete AV node ablation underwent serial ablations beginning at the level of the coronary sinus os progressing in a superior and anterior direction toward the His bundle. Serial atrial extrastimulus testing was performed to determine the effect of the progressive posteroseptal ablation in the region of the coronary sinus on the AV node antegrade refractory curve. Two of 22 patients had antegrade dual AV node pathways before ablation. Three patterns of response to serial ablation were noted. In 10 patients (45%), loss of the terminal portion of the AV node antegrade refractory curve occurred without evidence of fast pathway injury. In 7 patients (32%) the curve was shifted upward and to the left, consistent with nonspecific AV node damage. In 5 patients (23%), no effect could be attained before induction of complete AV block at superior and anterior ablation sites. Clinical variables and site of ablation did not predict response to serial ablations. CONCLUSIONS: These data suggest that the mechanism of benefit of AV node modification in this population may be through elimination of "slow pathway" tissue in half of patients and nonspecific injury in the remainder. Modification without complete AV block may not be possible in a minority of patients, as the response to progressive ablation appears to be "all or none" conduction.

Aged↗
PubMed1997

Hysteresis of the RT interval with exercise: a new marker for the long-QT syndrome?

BACKGROUND: The diagnosis of the long-QT syndrome (LQTS) may be difficult to establish in patients with normal or borderline prolongation of the QT interval. Noninvasive markers are needed to identify patients with LQTS. METHODS AND RESULTS: Fourteen patients with known LQTS, 9 unaffected family members, and 40 control subjects underwent modified Bruce protocol exercise testing. The RT interval (peak of R wave to peak of T wave) and rate-corrected RT interval (RTc) were measured during exercise and recovery. The RT interval at 1 minute into recovery was subtracted from the RT interval at a similar heart rate during exercise (deltaRT). The RTc shortened by 61 milliseconds (ms) in the LQTS patients compared with 23 to 26 ms in the other two groups (P=.003 by ANOVA). The RT interval shortened in a linear fashion in all patients but demonstrated persistent shortening during recovery in the LQTS patients. This was manifested as a hysteresis loop in the curve relating the RT interval to cycle length. The hysteresis loop was present in 13 of 14 LQTS patients and only 4 of 40 control subjects. DeltaRT >25 ms had a sensitivity of 73%, a specificity of 92%, a positive predictive value of 79%, and a negative predictive value of 90% for LQTS. CONCLUSIONS: Hysteresis of the RT interval with exercise may be useful for the diagnosis of LQTS.

Adolescent↗
PubMed1997

Safety of slow pathway ablation in patients with atrioventricular node reentrant tachycardia and a long fast pathway effective refractory period.

Radiofrequency catheter ablation is an accepted primary therapy for atrioventricular (AV) node reentrant tachycardia (AVNRT). There is concern that slow pathway ablation in patients with a long anterograde fast pathway effective refractory period (ERP) may potentially impair subsequent node conduction. Eighteen patients (14 women; age 53 +/- 20 years) with symptomatic AVNRT, whose fast pathway ERP at baseline was > or = 500 ms, underwent slow pathway ablation. Their outcome was compared with 24 consecutive control patients (17 women; age 42 +/- 17 years) who underwent ablation for AVNRT whose fast pathway ERP at baseline was <500 ms (controls). Slow pathway ablation was successful in 16 patients (90%). One patient had inadvertent fast pathway ablation. In a second patient the slow pathway could not be ablated because of recurrent transient AV block. Ablation was successful in all patients in the control group. Transient AV block related to current application occurred in 4 patients (22%) versus 1 control (4%) (p = 0.07). After ablation, the AV node refractory period increased in patients (368 +/- 68 to 428 +/- 92 ms, p = 0.02) and in controls (282 +/- 35 to 336 +/- 55 ms, p <0.0001), but the fast pathway ERP shortened in both groups (patients: 558 +/- 63 to 428 +/- 92 ms, p = 0.003; controls: 356 +/- 53 to 336 +/- 55 ms, p = 0.05). Furthermore, the slope of the regression line relating to shortening of the fast pathway ERP to the baseline ERP was markedly steeper in patients compared with controls (1.9 vs 0.4, p <0.0001). The shortening of the fast pathway ERP was greater in patients compared with controls (122 +/- 130 vs 21 +/- 50 ms, p = 0.001). During a mean follow-up of 18 +/- 11 months, 1 patient with severe coronary artery disease died suddenly 2 years after ablation. There was no recurrence of clinical tachycardia, and none of the patients developed symptoms of bradycardia or required permanent pacing. Thus, slow pathway ablation in patients with AVNRT and a long fast pathway ERP is safe and effective.

Adult↗
PubMed1997

Recurrent syncope. Experience with an implantable loop recorder.

The cause of recurrent syncope is often difficult to determine when initial laboratory investigations are negative. Advances in implantable monitoring technology permit long-term monitoring of the electrocardiogram in patients with recurrent undiagnosed syncope. A pilot device implanted in the left pectoral region established the cardiac rhythm during syncope in all 20 of 24 patients who developed syncope during follow-up. The cause was arrhythmic in 10 and nonarrhythmic in 10. Therapy resulted in resolution of symptoms in 17 of 20 patients. The implantable loop recorder is a promising diagnostic tool for investigation of syncope.

Electrophysiology↗
PubMed1997

Current role of pharmacologic therapy for patients with paroxysmal supraventricular tachycardia.

Intravenous antiarrhythmic drugs will continue to have an important role in the acute management of SVT. Long-term antiarrhythmic drug therapy is often effective in preventing or reducing frequency and severity of arrhythmic episodes. The cost, adverse effects, and inconvenience of long-term drug therapy will result in the increasing use of curative ablation for most individuals with problematic SVT.

Adenosine↗
PubMed1997

Effective use of a novel rate-smoothing algorithm in atrial fibrillation by ventricular pacing.

BACKGROUND: It is still unknown whether a fast heart rate or an irregular ventricular response in atrial fibrillation causes tachycardiomyopathy. Reduction in the variability of RR intervals without an increase in heart rate might be an alternative treatment when antiarrhythmic drugs fail to control the irregularity accompanying atrial fibrillation. SUBJECTS AND METHODS: Eight patients underwent temporary right ventricular pacing, using a novel rate-smoothing algorithm prior to DC cardioversion or His bundle ablation. A rate-smoothing algorithm was utilized by right ventricular apical stimulation. Spontaneous and paced RR intervals during atrial fibrillation were quantified and processed for statistical analysis. RESULTS: The rate-smoothing algorithm resulted in a substantial reduction in the variance of the RR intervals (slow mode 73.1%, fast mode 40.0%) and RR range (slow mode 49.3%, fast mode 34.3%). In contrast to previous algorithms, the mean heart rate during pacing intervention in atrial fibrillation did not change significantly to the heart rate directly preceding the pacemaker intervention (+2%). CONCLUSIONS: This initial study of the novel rate-smoothing algorithm shows that pacing intervention is a relatively safe, rapid and reliable alternative therapy for controlling irregular ventricular rhythms due to atrial fibrillation. Incorporation of the algorithm in implantable pacemakers appears justified, but demands further prospective studies in patients to evaluate relief of symptoms and reduction of tachycardiomyopathy due to atrial fibrillation.

Aged↗
PubMed1997

Cognitive dysfunction after ventricular fibrillation during implantable cardiovertor/defibrillator procedures is related to duration of the reperfusion interval.

The insertion of implantable cardioverter/defibrillators (ICD) requires induction of repeated episodes of ventricular fibrillation (VF). The neuropsychological repercussions associated with repeated inducement of hypotension and cerebral ischemia are unknown. In this prospective clinical trial, 1 day prior to ICD assessment/implantation and 5 days postprocedure, 14 patients underwent neurological and cognitive screening. Cognitive dysfunction was defined as impaired performance in one of four cognitive domains. Neurological impairment was defined as a decrement of 2 or more points from baseline of a total possible score of 45 points. Intraoperative hemodynamics, including the reperfusion interval (RI; end of preceding fibrillation to beginning of the next), were recorded. Patients underwent an average of 12 +/- 6 episodes of VF with average duration of mean arterial pressure (MAP) <50 mm Hg for 17 +/- 9 s (range 6-39 s) and of MAP <30 mm Hg for 11 +/- 5 s (range 2-22 s). Nine patients, in none of whom the predetermined criteria for neurologic impairment was met, demonstrated a new subtle neurologic finding postoperatively. Ten of 14 patients met the criterion for cognitive dysfunction 5 days postoperatively. The mean RI between episodes of VF was significantly different between those patients demonstrating cognitive dysfunction and the unimpaired patients (3.1 +/- 0.5 min in the group with cognitive dysfunction vs 3.9 +/- 0.8 min in the unimpaired group, P = 0.027). Five patients without cognitive impairment had longer RI between episodes of circulatory arrest than those showing impaired cognition. We conclude that cognitive dysfunction can occur after insertion of ICD and is related to the duration of RI.

Adult↗
PubMed1997

Maturation of the sensed electrogram amplitude over time in a new subcutaneous implantable loop recorder.

The cause of recurrent syncope may be difficult to determine if the diagnosis is not established from initial noninvasive and invasive testing. Eighteen patients with recurrent syncope and negative tilt table and electrophysiological testing underwent implantation of a left pectoral subcutaneous loop recorder. This device "freezes" the preceding 7.5 or 15 minute rhythm strip after magnet application after spontaneous syncope. Baseline and follow-up electrograms were routinely recorded, and patients were followed until syncope recurred. Three patients had syncope within 1 month of implantation and were excluded from this report. Implantation electrogram amplitude was 250 +/- 124 microV and increased to 291 +/- 114 microV at 2-3 months, and increased further to 353 +/- 167 microV at 4-6 months (P < 0.001, ANOVA). Syncope recurred in 14 of the 15 patients. An arrhythmic basis for syncope was established (n = 7) or excluded (n = 7) in every patient who had recurrent syncope. All syncopal episodes were associated with diagnostic sensed electrograms. The increase in sensed electrogram amplitude over time suggests a maturation of the device-tissue interface. These results support the long-term viability of this implantable monitoring technique.

Arrhythmias, Cardiac↗
PubMed1997

The effect of variable retrograde penetration on dual AV nodal pathways: observations before and after slow pathway ablation LDD.

Retrograde VA conduction is usually over the fast pathway and rarely over the slow pathway in patients with dual AV nodal pathways. It is unknown whether this apparent unidirectional conduction of the slow pathway is due to the lack of its retrograde conducting ability or the result of concealment. The effect of variable retrograde AV nodal penetration on antegrade AV nodal conduction was determined in patients with typical AV nodal reentrant tachycardia before and after the slow pathway ablation. Variable retrograde penetration was produced by delivering a ventricular extrastimulus simultaneously with (VE-0), 50 ms after (VE-50), or 100 ms after (VE-100) the last basic atrial stimulus, while atrial extrastimuli were used to determine changes of anterograde AV nodal effective refractory period (ERP) and A-H interval. The AV nodal functions measured without the ventricular extrastimuli served as the baseline. Although the mean slow pathway ERP was not significantly different among the different stimulation protocols, a significant shortening of the slow pathway conduction time (A-H from 348 +/- 60 to 324 +/- 119 ms, P < 0.05) was observed with upper level retrograde penetration of the AV node (VE-0). This facilitating effect became a prolonging effect when the retrograde penetration level moved to the lower level (VE-100, A-H from 324 +/- 119 to 366 +/- 122 ms, P < 0.05). The fast pathway ERP shortened with an upper level penetration (VE-0) but tended to prolong with a lower level retrograde-penetration (VE-100) both before and after the slow pathway ablation (preablation, from 348 +/- 143 of the baseline to 302 +/- 114 to 360 +/- 143 ms, P < 0.05; postablation, from 314 +/- 101 of the baseline to 274 +/- 118 to 361 +/- 143 ms, P < 0.05). The mean A2-H2 interval of the slow pathway was significantly shorter than the baseline (350 +/- 44 ms) with VE-0 (249 +/- 48 ms, P < 0.05) and VE-50 stimulation (285 +/- 82 ms, P < 0.05) but not with VE-100 stimulation (330 +/- 83 ms, P = NS). Before slow pathway ablation, the A2-H2 interval of the fast pathway at equal coupling intervals was shorter than the baseline (165 +/- 53 ms) with VE-0 (144 +/- 47 ms, P < 0.01) and VE-50 stimulation (152 +/- 43 ms, P < 0.05) but tended to be longer with VE-100 stimulation (175 +/- 47 ms, P = NS). After slow pathway ablation, the mean A2-H2 interval at the same coupling interval was shorter than the baseline (173 +/- 39 ms) with VE-0 (139 +/- 35 ms, P < 0.05), VE-50 (153 +/- 32 ms, P = 0.05) but tended to be longer with VE-100 stimulation (178 +/- 49 ms, P = NS). We conclude that: (1) concealed retrograde conduction can be demonstrated in both the slow and the fast AV nodal pathways; and (2) concealed retrograde conduction may either shorten or prolong anterograde refractoriness and conduction time, depending on the level of retrograde penetration.

Adult↗
PubMed1997

Utility of full electrophysiological study before accessory pathway ablation in Wolff-Parkinson-White syndrome.

BACKGROUND: A single catheter technique has been described for ablation in patients with Wolff-Parkinson-White syndrome. It is unknown how often omission of a standard electrophysiological study would lead to misdiagnosis based on an assumption that the manifest accessory pathway is responsible for clinical tachycardia. OBJECTIVES: To examine the contribution of the standard electrophysiological study versus an abbreviated, single catheter approach in patients with Wolff-Parkinson-White syndrome and an overt delta wave electrocardiographically. PATIENTS AND METHODS: One hundred and fifty consecutive patients with a delta wave present on electrocardiogram referred for ablation had prior full diagnostic electrophysiological study. RESULTS: In 83% (124 of 150) of patients, the index accessory pathway was responsible for tachycardia and single catheter ablation would suffice. In 11% (17 of 150) of patients, the index pathway was not found to be the culprit producing tachycardia and in another 6% (nine of 150) additional information was obtained from electrophysiological study with possible clinical significance. CONCLUSIONS: Omission of the full diagnostic electrophysiological study is acceptable in the majority of patients presenting with a delta wave on electrocardiogram. However, important clinical information is missed in a sizeable minority of patients.

Adolescent↗
PubMed1997

Time-dependent change in fast pathway refractoriness after slow pathway ablation in atrioventricular node reentrant tachycardia. Mansfield Polaris Investigators.

OBJECTIVE: To determine the time course of change in fast pathway refractoriness after slow pathway ablation. BACKGROUND: Antegrade fast pathway refractoriness has been observed to shorten in patients undergoing slow pathway ablation for atrioventricular (AV) node reentrant tachycardia. The time course and mechanism of this observation have not been explained. METHODS: Twenty-eight patients with AV node reentrant tachycardia and dual AV node pathways undergoing slow pathway ablation had the fast pathway effective refractory period (ERP) assessed immediately before, and at 0, 15, 30 and 45 mins after slow pathway ablation (Group 1). Twenty-five additional patients with AV node reentry and dual pathways involved in a multicentre protocol evaluating the Mansfield Polaris LE catheter underwent assessment of fast pathway refractoriness before and after slow pathway ablation, and at a routine three-month follow-up electrophysiology study (Group 2). RESULTS: In Group 1, antegrade fast pathway ERP fell from 394 ms before ablation to 334 ms immediately after slow pathway ablation, increased to 348 ms within 15 mins and was 353 ms at 45 mins (ANOVA P < 0.001). Retrograde fast pathway ERP fell from 325 ms before ablation to 294 ms at 45 mins (P = 0.02). In Group 2, antegrade fast pathway ERP fell from 390 ms before ablation to 337 ms after ablation, and rose to 362 ms at three months (P = 0.01). Retrograde fast pathway ERP also fell from 347 ms to 319 ms after ablation (P = 0.01), and remained unchanged at three months. CONCLUSION: Slow pathway ablation results in an immediate and sustained change in antegrade and retrograde first pathway refractoriness. There are immediate reversible and long term nonreversible components to this phenomenon. The latter finding may be related to loss of electrotonic inhibition of the fast pathway by the slow pathway.

Adult↗
PubMed1996

Multicenter comparison of truncated biphasic shocks and standard damped sine wave monophasic shocks for transthoracic ventricular defibrillation. Transthoracic Investigators.

BACKGROUND: The most important factor for improving out-of-hospital ventricular fibrillation survival rates is early defibrillation. This can be achieved if small, lightweight, inexpensive automatic external defibrillators are widely disseminated. Because automatic external defibrillator size and cost are directly affected by defibrillation waveform shape and because of the favorable experience with truncated biphasic waveforms in implantable cardioverter-defibrillators, we compared the efficacy of a truncated biphasic waveform with that of a standard damped sine monophasic waveform for transthoracic defibrillation. METHODS AND RESULTS: The principal goal of this multicenter, prospective, randomized, blinded study was to compare the first-shock transthoracic defibrillation efficacy of a 130-J truncated biphasic waveform with that of a standard 200-J monophasic damped sine wave pulse using anterior thoracic pads in the course of implantable cardioverter-defibrillator testing. Pad-pad ECGs were also examined after transthoracic defibrillation. After the elimination of data for 24 patients who did not meet all protocol criteria, the results from 294 patients were analyzed. The 130-J truncated biphasic pulse and the 200-J damped sine wave monophasic pulse resulted in first-shock efficacy rates of 86% and 86%, respectively (P = .97). ST-segment levels measured 10 seconds after the shock in 151 patients in sinus rhythm were -0.26 +/- 1.58 and -1.86 +/- 1.93 mm for the 130- and 200-J shocks, respectively (P < .0001). CONCLUSIONS: We found that 130-J biphasic truncated transthoracic shocks defibrillate as well as the 200-J monophasic damped sine wave shocks that are traditionally used in standard transthoracic defibrillators and result in fewer ECG abnormalities after the shock.

Adolescent↗
PubMed1996

Atrioventricular node reentry with 'smooth' AV node function curves: a different arrhythmia substrate?

BACKGROUND: Some patients with otherwise typical AV node reentry do not manifest discontinuous AV node function curves. We examined the effects of an ablation in the slow-pathway region in patients with smooth AV node function curves. METHODS AND RESULTS: Fifteen patients with AV node reentrant tachycardia (AVNRT) and discontinuous AV node function curves were compared with 15 patients with AVNRT and smooth AV node function curves. In the group with discontinuous curve, the "net" anterograde effective refractory period (AERP) of the AV node increased (270 +/- 28 versus 304 +/- 37 ms, P = .03) and AERP of the remaining fast pathway decreased (367 +/- 100 versus 304 +/- 37 ms, P = .026) after the ablation. In the group with a smooth curve, the AERP of the AV node increased (266 +/- 42 versus 299 +/- 76 ms, P = .07) and the anterograde Wenckebach cycle length increased (336 +/- 66 versus 379 +/- 86 ms, P = .008) after the ablation. Retrograde conduction over the AV node was similar in both groups and was unchanged after ablation. The longest attainable AH interval (AHmax) measured during atrial extrastimulus testing was more prolonged in patients with a discontinuous curve than in patients with a smooth curve (326 +/- 48 versus 250 +/- 70 ms, P = .002). The AHmax shortened in both groups after ablation (326 +/- 48 versus 173 +/- 34 ms, P < .0001, and 250 +/- 70 versus 179 +/ 34 ms, P < .0003, respectively) and were similar. Successful ablation in the slow-pathway zone in patients with a smooth AV node function curve resulted in the loss of the "tail" of the curve representing the slow pathway. CONCLUSIONS: These data suggest that the smooth AV node function curve consists of two distinct components representing both fast and slow AV node pathways even when the typical discontinuity is absent.

Atrioventricular Node↗
PubMed1996

Anatomic substrate for idiopathic left ventricular tachycardia.

BACKGROUND: Idiopathic left ventricular tachycardia (ILVT) characterized by QRS complexes with right bundle-branch block (RBBB) morphology and left axis deviation is a distinct clinical syndrome that also demonstrates a characteristic response to verapamil and inducibility from the atrium in patients without structural heart disease. A false tendon has been described in the left ventricle in a patient with ILVT in whom surgical resection of the false tendon resulted in cure. We hypothesized that the false tendon is responsible for the genesis of similar ventricular tachycardia (VT) in others. METHODS AND RESULTS: We performed transthoracic (TTE) and/or transesophageal (TEE) two-dimensional echocardiograms in 15 patients undergoing catheter ablation for ILVT. There were 12 men and 3 women (mean age, 31 +/- 12 years, with average symptom duration of 11 +/- 9 years). The mean VT cycle length was 360 +/- 70 ms, and all had RBBB morphology with left axis deviation. Cardiac chamber sizes, left ventricular wall thickness, and wall motion were normal in all ILVT patients. TTE and/or TEE demonstrated a false tendon extending from the posteroinferior left ventricular free wall to the left ventricular septum in all ILVT patients. The false tendons were thick (> or = 2 mm maximal thickness) in 5 patients and thin (< 2 mm maximal thickness) in 10 patients. We compared ILVT patients with a control group of 671 consecutive patients referred for echocardiography for other reasons. The mean age for the control group was 42 years. A false tendon was seen in the left ventricle in 34 of 671 (5%). In the control group patients with a false tendon, 2 patients had a history of VT (left bundle-branch block morphology) and 1 had ventricular fibrillation. The false tendons in the control patients were also oriented transversely across the ventricular cavity but were somewhat thinner (< 2 mm maximal thickness in 32 of 34 patients). Catheter ablation with the use of radiofrequency and/or direct current applied to the posteroapical septum resulted in cure in 14 of 15 patients. CONCLUSIONS: A false tendon extending from the posteroinferior left ventricle to the septum is a consistent finding in patients with ILVT and probably is responsible for this unique arrhythmia. The mechanism by which the false tendon precipitates tachycardia is speculative, but possibilities include conduction through the false tendon or by producing stretch in the Purkinje fiber network on the interventricular septum.

Adult↗
PubMed1996

Immune response to polyvalent melanoma cell vaccine in AJCC stage III melanoma: an immunologic survival model.

BACKGROUND: Our polyvalent, allogeneic melanoma cell vaccine (MCV) induces immunoglobulin M (IgM) and immunoglobulin G (IgG) class antibodies to a 90-kDa glycoprotein melanoma-associated antigen (MAA). Additionally, MCV induces delayed-type hypersensitivity (DTH) responses that we previously correlated with survival. We hypothesized that early DTH responses to MCV and early humoral responses to the 90-kDa MAA expressed on MCV cells may be predictive of overall survival. We tested this hypothesis by monitoring immunologic profiles in 59 patients with melanoma who were receiving MCV after surgical resection of regional lymph node or soft-tissue metastases. METHODS: Blood was drawn before vaccine administration, biweekly for 6 weeks, and then monthly. DTH to MCV was recorded at 0, 2, 4, and 8 weeks of MCV therapy. Mean antibody titers during the first 6-week interval were calculated. Changes in DTH were calculated as the difference between peak and prevaccine values (delta DTH). RESULTS: At a median follow-up of 75.6 months (range 5-138), univariate analysis assigned prognostic significance to gender (p = 0.046), lymph node involvement (p = 0.024), delta DTH (p = 0.044), mean anti-90-kDa MAA IgG (p = 0.0009), and mean anti-90-kDa MAA IgM (p = 0.0014). In multifactorial analysis, only the three immunologic variables significantly impacted survival (p = 0.046, 0.0005, and 0.0053, respectively). A mathematical model based on delta DTH and mean anti-90-kDa MAA IgG and IgM titers closely approximated the observed individual and overall survival rates. CONCLUSIONS: The correlation between overall survival and initial humoral/cellular immune responses to MCV immunotherapy may be useful in selecting patients most likely to benefit from prolonged adjuvant immunotherapy.

Adolescent↗
PubMed1996

Mapping of Reis-Bücklers' corneal dystrophy to chromosome 5q.

PURPOSE: Recently several autosomal dominant corneal stromal dystrophies have been mapped to chromosome 5q. Therefore, we tested whether Reis-Bücklers' corneal dystrophy, an autosomal dominant trait, was also linked to the same region. METHODS: Five generations of a single family with Reis-Bücklers' corneal dystrophy were ascertained. Twenty-two family members were examined, and 11 were found to be affected. Blood was obtained for genetic linkage analysis. RESULTS: Several genetic markers on chromosome 5q were strongly suggestive of linkage or confirmed linkage (LOD score > 3.0). Multipoint analysis generated a maximum LOD score of 4.25 between D5S414 and IL-9. CONCLUSIONS: Reis-Bücklers', lattice type 1, Avillino, and granular corneal dystrophies all map to the same genetic locus. This suggests that one of the following might be true: (1) that a corneal gene family exists in this region; (2) that these corneal dystrophies represent allelic heterogeneity (that is, different mutations within the same gene manifest as different phenotypes); or (3) that these are all the same disease.

Basement Membrane↗