Family screening in brugada syndrome patients

Background

Brugada syndrome (BS) is a rare inherited channelopathy associated with sudden cardiac death (SCD) and family screening (FS) of index patients (pts) is recommended. However, data about pts identified through FS is lacking.

Aim

To compare index pts to non-index pts identified through systematic FS.

Methods

Single-center retrospective study of BS pts followed by the Arrhythmology Department. FS was offered to 1st degree relatives of all index pts through primary care services and a once-weekly voluntary open appointment. Genetic counselling was performed when indicated. Index and non-index pts were compared regarding baseline characteristics and events during the follow-up (syncope of probable arrhythmic origin, ventricular tachycardia/ventricular fibrillation (VT/VF) and SCD).

Results

We included 165 pts (61% males, mean age 47±15 years) and 72 (44%) were identified through FS. Non-index pts were diagnosed at a younger age (42±14 vs 51±14 years, p <.001), were more often female (57% vs 25%, p<.001), were diagnosed predominantly through provocative test with ajmaline/flecainide (88% vs 47%, p<.001) and had less documented spontaneous type 1 ECG pattern (17% vs 59%, p<.001). A type 2 pattern was identified in 18 (25%) non-index pts.

Genetic testing was performed in 38 (53%) non-index pts: 6 had a pathogenic SCN5A mutation, 18 a likely pathogenic SCN5A mutation and 12 a mutation of uncertain significance.

At diagnosis, 24 (33%) non-index pts had history of syncope, 3 (4%) had nocturnal agonal respiration and 11 (15%) had palpitations with no differences between both groups (p=.119). Non-index pts were less likely to implant a cardioverterdefibrillator (14% vs 38%, p=.001).

During a median follow-up of 28 (IQR 16–41) months, 10 (6%) pts had an event - 2 (3%) in the non-index group (2 syncope) and 8 (9%) in the index group (1 syncope; 7 VT/VF) - with no significative differences between groups (p=.432). There were nocardiovascular deaths.

Conclusions

FS identified a considerable proportion of BS pts. Non-index pts were younger at the time of the diagnosis and had less spontaneous type 1 pattern. No differences were found in events between index and non-index pts, however, the event rate was low. Systematic FS can identify individuals at risk of SCD earlier, allowing close monitoring and, when indicated, appropriate treatment.

Funding Acknowledgement

Type of funding sources: None.

Electrophysiologic study for risk stratification in Brugada Syndrome: does it still matters?

Background

The value of eletrophisiologic study (EPS) with programmed ventricular stimulation for risk stratification in patients with Brugada Syndrome (BS) remains controversial.

Purpose

The aim of this study is to determine the clinical and electrocardiographic predictors of positive EPS and to evaluate whether the induction of malignant ventricular dysrhythmias in the EPS is a predictor of events

Methods

A retrospective study was carried out of patients with spontaneous type 1 Brugada pattern followed up in Arrhythmology consultation at our Hospital. From this population, patients who underwent EPS for stratification of dysrhythmic risk were selected. Clinical and electrocardiographic variables were analyzed. Hospital records and monitoring data from cardiac devices were consulted. Statistical analysis was performed using SPSS 20.0.

Results

Fourty nine patients were included, with a mean age at the beginning of follow-up of 45±14 years, 40 (82%) of whom were male. In 16 individuals (33%) the EPS was positive with induction of malignant ventricular dysrhythmias. All patients with positive EPS implanted an implantable cardioverter-defibrillator and of the 32 patients with negative EPS, 10 implanted an implantable event recorder. The group of patients with positive EPS had a higher proportion of male patients (88% vs 78%). The median follow-up time was 31 months.

The family history of sudden death, family history of BS, or identification of a genetic variant classified as pathogenic or probably pathogenic did not present any relationship with EPS positivity. Of the analyzed electrocardiographic markers, PR interval (178±29 vs 171±27) and QRS duration (119±24 vs 113±15) tended to be longer in patients with positive EPS. Additionally, it was found that 74% of patients with a QRS of less than 120 ms had a negative EPS.

In the analysis of the value of EPS in the stratification of dysrhythmic risk, it was found that of all the patients who suffered events (4), 75% had positive EPS. Of the patients with negative EPS, only 3% (1) presented events in the follow-up. However, there was no significant association between these variables.

Conclusion

In this population, the analysed clinical elements did not correlate with the EPS result. Although there was no statistical significance, there was a tendency for patients with narrower QRS to be more likely to have negative EPS. Accordingly with published data, it was found that the EPS result was not a predictor of events during the follow-up period, which highlights the difficulty of risk stratification in patients with BS.

Funding Acknowledgement

Type of funding sources: None.

Gender related differences in brugada syndrome

Background

Brugada syndrome (BS) is a heritable channelopathy with male predominance. Males (M) seem to have a higher risk of arrhythmic events, although, there is limited data regarding gender differences in BS.

Aim

To compare the differences between genders in a Portuguese sample of BS patients (pts).

Methods

Single-center retrospective study of BS pts followed by the Arrhythmology Department. Pts were divided according to gender and compared regarding baseline characteristics and electrocardiographic (ECG) parameters that possibly predict the arrhythmic risk (significative S wave in DI, R wave sign, Tpeak-Tend interval and fragmented QRS). The events during follow-up were syncope of probable arrhythmic origin, ventricular tachycardia/ventricular fibrillation (VT/VF) and sudden cardiac death (SCD).

Results

A total of 165 pts were included; 64 (39%) were female (F) and the mean age at diagnosis was 47±15 years. The diagnosis was made by family screening (FS) in 72 (44%) pts. Sixty-seven pts (41%) had spontaneous type 1 pattern, 59 (36%) had history of syncope and 5 (3%) had history of aborted SCD. A positive genetic test was identified in 41 (25%) pts. Sixty-three (38%) pts were referred for an electrophysiological study (EEF) which was positive in 17 (27%) pts. A cardioverter-defibrillator was implanted in 45 (27%) pts. Females were more often diagnosed by FS (64% vs 31%, p <.001), had less type 1 spontaneous pattern (22% vs 53%, p<.001) and had no atrial fibrillation (0% vs 7%, p=.043). They performed EEF less frequently (22% vs 49%, p<.001) and had less spontaneous pattern during treadmill stress test (8% vs 33%, p=.004).

Regarding ECG parameters, females had shorter QRS interval (104±12 vs 115±18 ms, p<0.001), less frequent aVR sign (3% vs 27%, p<0.001), less significative S wave in DI (31% vs 55%, p=0.004), and a tendency for a shorter Tp-Te interval (80 vs 100 ms, p=0.051). Corrected QT interval was longer in females (396 vs 392ms, p=0.044). During a median follow-up of 28 (IQR 16–41) months, 7 pts had VT/VF (2F, 5M) and 3 had syncope (3M), with no differences between gender (p=0.287). There were no cardiovascular deaths.

Conclusion

In BS, female pts are more often diagnosed by FS and have less spontaneous type 1 pattern. Gender appears to affect basal ECG characteristics in BS, namely in parameters that may predict arrhythmic risk. Further studies are important to clarify the role of gender in prognosis and risk stratification of BS pts.

Funding Acknowledgement

Type of funding sources: None.

Device therapy guided by implantable loop recorders: predictors of bradyarrhythmic events

Background

Implantable loop recorders (ILR) improved diagnostic yield in unexplained syncope patients (pts). Data on possible predictive factors for bradycardia requiring device implantation in these pts is limited. We aim to identify clinical predictors for device implantation due to a significant bradyarrhythmia in patients who underwent ILR insertion for the study of syncopal/presyncopal (S/pS) events.

Methods

Single-center retrospective study of patients who implanted an ILR for the study of unexplained S/pS episodes between 2013 and 2018. The primary endpoint was a documented bradyarrhythmia requiring device implantation during the follow-up.

Results

A total of 251 pts were included. Mean age was 68±15 years and 53% were female. The majority of pts (220; 88%) had normal ejection fraction. Fifty-two (21%) pts had atrial fibrillation (AF). Regarding basal electrocardiographic characteristics, 34 (14%) pts had 1st degree auriculo-ventricular block (AVB), 31 (12%) pts had left bundle branch block (L-BBB), 22 (9%) pts had R-BBB and 13 (5%) pts had bifascicular block.

During a median follow-up of 20 (IQR 9–34) months, 74 (29%) pts required device implantation because of a significant bradyarrhythmia (92% pacemaker, 4% CRT, 4% ICD). Median duration from ILR until device implantation was 5 (IQR 1–10) months. The indications were sick-sinus-syndrome in 47 (64%) pts, advanced AV block in 23 (31%) pts and symptomatic slow AF in 4 (5%) pts.

Patients who required device implantation were older (73±12 vs 66±15 years, p <0.001), had more hypertension (73% vs 59% p=0.048), a higher prevalence of AF (34% vs 15% p=0.001) and a lower glomerular filtration rate (GFR<60 ml/min: 32% vs 21%, p=0.047). They also had more 1st AVB (22% vs 11%, p=0.026) and intraventricular conduction disturbances (38% vs 25%, p=0.025). There was a trend for a higher device implantation in pts with concomitant 1st AVB and left anterior fascicular block (7% vs 2%, p=0.063)

In a logistic regression model, age >75 years (HR: 1.7; 95% CI: 1.1–2.8) and the presence of AF (HR: 1.8; 95% CI: 1.1–3.0) were independent predictors for device implantation.

Conclusion

An older age and the presence of AF were independent predictors for device therapy in pts who implanted an ILR for the study of S/pS. These factors may identify a higher risk group and should be considered in the initial workup of these pts.

Funding Acknowledgement

Type of funding source: None

Are international travelers from Portugal aware of malaria? Pre-travel assessment between 2019-2020

Background

Malaria is the main cause of death by infection among travelers. It may be prevented via chemoprophylaxis and personal protection. In 2017, European Centre for Disease Prevention and Control reported 8401 cases in Europe-8023 imported (99,8% travel-related). Misperception of the risk and inadequate pre-travel preparation are some of the reasons for these case numbers. The main goal of this study was to assess travelers' knowledge of malaria to improve medical advice in pre-travel consultations in the Oporto international vaccination centre (OIVC), minimizing the risk among travelers going to malaria endemic regions.

Methods

Before their pre-travel consultation in OIVC, 452 travelers filled the questionnaire with demographic issues, journey characteristics and answers about malaria's etiology, prevention and treatment. All travelers signed an informed consent form. Data were collected between July 2019 and January 2020 and analyzed via descriptive statistics and hypothesis test for comparing two populations proportions for each question.

Results

40,4% of travelers age was 26 - 35 years; 52,3% were female; and 67,5% of the planned trips were 1-3 week-long, mainly for tourism (n = 285). For most of malaria questions, travelers holding a university degree (n = 352) exhibited a statistically significant difference (p < 0,005) in knowledge with an average of 70,5% correct answers compared to 58.5% of those with lower education level. However, regarding previous pre-travel appointments: for the majority of questions knowledge was similar (p > 0,005) comparing to those who had first pre-travel consultation (n = 287), with an average of correct answers of 73,7% and 65,5%, respectively.

Conclusions

A stronger focus on malaria in pre-travel medical advice is necessary to increase travelers' knowledge. It is also essential to adapt malaria information to travelers' characteristics- in view of the lower percentage of correct answers by those with a lower education level.

Key messages

Malaria is a potential health risk for international travellers and an important cause of death among them. This may be caused by inaccurate perception of risk and sub-optimal pre-travel preparation. This study is the largest in Portugal to assess traveleŕs knowledge about malaria. It is crucial in order to improve medical advice and minimize the risk.

P1456 Pacemaker and percutaneous aortic valve endocarditis - a complex decision

CASE REPORT

We describe the case of a 64-year-old man who was referred because of a fever. He had history of hypertension, dyslipidemia, atrial fibrillation, chronic obstructive pulmonary disease and a right lung pneumectomy due to epidermoid lung cancer diagnosed twenty-five years ago. He implanted dual-chamber definite pacemaker ten years ago and had a transcatheter aortic valve implantation (TAVI) in the previous year due to severe aortic stenosis and a high surgical risk.

He was hospitalized 2 months ago because of a respiratory infection. Blood cultures were positive for an Enterococcus faecalis. A transthoracic echocardiogram was performed and had no evidence of vegetations.

After one month, he had recurrence of fever and was again admitted. On physical examination he was hemodynamically stable, with signs of peripheral congestion and no heart murmur on cardiac auscultation. Blood cultures were again positive for Enterococcus faecalis. The transesophageal echocardiogram (TEE) showed a biologic aortic valve with thickened leaflets and small nodular structures suggestive of vegetations. There was a small periprosthetic leak and no obstruction or suspected perivalvular abscesses. There was also a small vegetation with 0,45*0,3 cm in the auricular pacemaker lead. A thoraco-abdomino-pelvic computed tomography scan showed no embolic complications. A diagnosis of pacemaker and TAVI endocarditis was made. The patient started directed antibiotic therapy (ceftriaxone and ampicillin).

The case was discussed in Heart Team and because of high surgical risk, medical treatment was decided. The patient completed antibiotic treatment with negative blood cultures and apyrexia. A repeated TEE showed persistence of vegetations, without development of local complications.

It was decided to discharge the patient under palliative suppressive antibiotic treatment with levofloxacin after discussion with the infectious disease doctor. In a follow-up evaluation, he remained clinically stable, without recurrence of fever.

DISCUSSION

As TAVI procedures are performed more frequently, a higher number of late complications are expected. Prosthetic valve endocarditis after TAVI is a complex situation, whose treatment strategy is not well-defined, particularly because these patients are usually of high surgical risk. This case describes a complex clinical picture and highlights the difficulty in decision-making in these situations. Also, it pretends to reinforce the need to discuss in a Heart Team the best treatment options.

P199 Mitral valve annular disjunction prevalence and significance amongst patients with mitral valve prolapse

Background

Mitral valve prolapse (MVP) is a common and usually benign entity. Occasionally, patients with MVP present with mitral annular disjunction (MAD), whose prevalence and clinical significance are still not clearly established.

Purpose

This study aimed to define the prevalence of MAD in a population of patients with MVP and study its echocardiographic and clinical implication.

Methods

A total of 31 patients with MVP who underwent echocardiographic evaluation in our laboratory were retrospectively evaluated. Echocardiographic, demographic and clinical variables were assessed. Disjunction amplitude (DA) was measured in parasternal long axis view (PLAX) and MAD was considered present if a separation of ≥ 5mm was verified. Annular diameter was measured in PLAX and apical four chamber view (A4C) both in systole and diastole.

Results

MAD was identified in 9 patients (29%), having a mean DA of 12.3 ± 3.2 mm. The group of patients with MAD was significantly younger than the group without MAD (mean age of 54 ± 18 vs 67 ± 15 years; p = 0.001), but there were no significant differences regarding gender, height, weight or cardiovascular risk factors. DA was inversely correlated with body surface area (r=-0.8, p = 0.009). Systolic annular diameters in PLAX and A4C views were increased in patients with MAD (4.2 ± 0.6 vs 3.6 ± 0.7 mm, p= 0.04 and 4.8 ± 0.7 vs 4.1 ± 0.7 mm, p = 0.025, respectively). The difference between systolic and diastolic diameters in PLAX was also greater in MAD (0.5 ± 0.2 vs 0.1 ± 0.3 mm, p = 0.007). Posterior wall thickness (8.5 ± 1.1 vs 9.7 ± 1.4 mm, p = 0.035), indexed left ventricular mass (89.0 ± 15.8 vs 110.6 ± 40,2 g/m2, p = 0.04) and ascending aortic dimensions (28.7 ± 6.7 vs 37.4 ± 3.6 mm, p = 0.018) were notably inferior in MAD patients, as was left ventricle ejection fraction (LVEF) (57.5 ± 5.8 vs 62.6 ± 4.9 %, p = 0.0023). No differences were found in chamber volumes. Similarly, eletrocardiographic parameters were identical in both groups. Five patients (56%) in the group with MAD had documentation of events (palpitations, dizziness, syncope or sudden cardiac death), in contrast with just 3 (21%) in the group without MAD, although statistical significance was not achieved (p = 0.078).

Conclusion

This study revealed that MAD is common among patients with MVP and is associated with altered annulus dynamics during the cardiac cycle. Its association with younger individuals, lower LVEF and, apparently, more clinical events highlight the importance of this entity.

P317 Assessment of atrial function in elite soccer players

Introduction

Athlete´s heart is associated with physiological remodelling as a consequence of repetitive cardiac loading. Atrial dilation may occur in athletes, but atrial size is insufficient to provide mechanistic information about the atrium itself and an increase in atrial size is not intrinsically an expression of atrial dysfunction. Two dimensional (2D) LA strain analysis by speckle tracking emerges as a gold standard for evaluation of atrial myocardial function.

Aim

To compare LA function between elite soccer players and sedentary healthy controls through 2D-strain analysis by speckle tracking.

Methods

We included 44 consecutive male professional soccer players and 25 sedentary male healthy controls, matched by age and race. All subjects underwent transthoracic echocardiogram, including evaluation of LA diameter and volume and 2D-strain analysis by speckle tracking. Peak atrial longitudinal strain (PALS) was measured at the end of the reservoir phase and peak atrial contraction strain (PACS) was measured just before the start of the active atrial contractile phase. The average of PALS and PACS was obtained from the 12 LA segments at apical 4 and 2-chamber views. The LA contraction strain index (CSI) (ratio PACS/PALS x100) was also calculated. SPSS 20.0 was used for statistical analysis.

Results

Mean age was similar between athletes and controls (22.3 ± 4.2 vs 25.0 ± 2.4 p = 0.13) as well as body mass index (23.3 ± 5.8 vs 24.6 ± 2.7 Kg/m2, p = 0.24).

Athletes had significantly higher LA volume (29.1 ± 6.9 vs. 21.1 ± 5.5, p < 0.001). No statistical differences were observed in LA diameter between the two groups (18.7 ± 2 vs 18.0 ±1.7, p = 0.163).

Athletes had significantly lower PALS (36.3%±5.8 vs. 44.2%±8.9, p < 0.001), PACS (9.5%±2.8 vs 15.3%±4.8, p < 0.001) and LA CSI (26.3 ± 7.8 vs. 35.0 ± 9.3, p < 0.001) than controls. LA volume was correlated with PALS (p < 0.001 r = 0.99), but not with PACS or CSI (p = 0.089 and p = 0.142, respectively).

Conclusion

This study showed that in top-level athletes LA PALS and PACS are lower and PALS correlates with LA volume, suggesting that LA suffers not only a morphological but also a functional remodelling in response to intensive exercise. This can be mediated by increased LA workload imposed by the increased left ventricular work.

P4408Cardiovascular response in diabetic patients submitted to treadmill electrocardiographic exercise stress test

Introduction

Diabetes mellitus (DM) is an entity commonly associated with neuropathy, a factor that may have repercussions on the cardiovascular system, specifically in its capacity to respond to stimuli.

Objectives

To evaluate the cardiovascular response to exercise in diabetic patients, comparing it with a control group.

Methods

Patients who underwent treadmill eletrocardiographic exercise stress test (EST) between January 2016 and November 2018 without the influence of negative chronotropic medication were included.

Results

A total of 187 patients were identified, having a mean age of 57±13 years, of whom 120 (64%) were of the male gender. Eighty-four (45%) were diabetic. The group of diabetic patients had a higher prevalence of arterial hypertension, however the number of classes of antihypertensive drugs was not significantly different between diabetic and non-diabetic patients. There were no significant differences in the remaining demographic variables. Patients with DM presented lower maximal heart rates (HR) (141±14 vs 148±19 beats/minute, p=0.015), lower HT reserve (59±16 vs 67±21 beats/minute, p=0.005), as well as a lower rate of HR fall in the recovery period (13±5 vs 16±5 beats/minute2, p<0.001). Total EST time was also lower in diabetic patients (median 7.0 IQR=3 vs 7.3 IQR=3.5 minutes, p=0.044). Additionally, the number of years since the time of diagnosis of DM was inversely correlated with the degree of increase in systolic blood pressure (SBP) with exercise (r=−0.22, p=0.045), and the pre-test SBP (median 135 IQR=24 vs 130 IQR=20 mmHg, p=0.048) and post-test SBP (median 150 IQR=20 vs 140 IQR=25 mmHg, p=0.007) were higher in patients with DM.

Discussion

In this study it was found that patients with DM present an impaired chronotropic response, both in exercise and recovery periods, and it was observed that the capacity to increase SBP is inversely correlated to the duration of DM. These data may reflect the neuropathic involvement in DM and its influence in the cardiovascular response to exercise.

P6579Genetic profile and predictors of positive genetic test in Brugada syndrome

Introduction

Brugada syndrome (BS) is a channelopathy with autosomal dominant transmission, incomplete penetrance and variable expression. There are 18 different gene mutations described in association with this syndrome, however 70% of patients remain without identifiable genetic cause. Genetic testing is appropriated for patients with clinical diagnosis but it is also a very important tool in familiar screening.

Aim

We aim to characterize genetic profile of patients with clinical diagnosis of BS and identify differences between patients with and without causative mutation.

Methods

We included patients followed by the arrhythmology department of our hospital with diagnosis of BS and that have performed genetic test (or patients who were identified through familiar screening and with negative genetic test in the index case). Patients identified through familiar screening with positive genetic test but no spontaneous electrocardiographic pattern, still awaiting pharmacologic provocative test at the time of enrolment – no clinical diagnosis - were excluded. Genetic test was considered positive when we found a pathogenic or probably pathogenic mutation. Mutations in PKP, SLMAP, CACNA, CACNB, SCN10A and CLASP genes considered of uncertain clinical relevance were not included as positive genetic test. We analysed differences between subset of patients with and without causative mutation regarding clinical and electrocardiographic variables. We performed multivariate analysis to find predictors of positive genetic test.

Results

From our 173 patients, 140 met the inclusion criteria and none exclusion criteria so they were enrolled. Patients were 61% male with mean age of 50±15 years old. Mean follow-up was 26±28 months; 24,4% of index cases were positive for causative mutation, 6,8% patients with pathogenic mutation in SCN5A gene and 17,6% with probably pathogenic mutation in SCN5A.

We haven't found significant differences between the 2 groups (negative and positive genetic test) in any clinical variable included. Regarding electrocardiographic variables, patients in whom a mutation was identified had longer PR interval (192±36 vs 170±28, p=0.001), longer QRS (121±19 VS 111±18 p=0.017), particularly when QRS>110ms (p=0,002), and longer QT (398±25 VS 370±45 p=0.015) In multivariate analysis, PR interval (p=0.032) and QRS>110ms (p=0,041) were independent predictors for positive genetic test.

Conclusion

In our BS population, there were no clinical differences between patients with and without causative mutation, also concerning events rate. Patients with positive genetic test have significantly longer PR interval and QRS>110ms than in patients with genetic test negative. Those results can be interpreted in relation to sodium channel disfunction in patients with SCN5A mutation.

Combined C4d and CD3 immunostaining predicts immunoglobulin (Ig)A nephropathy progression

A number of molecules have been shown recently to be involved in the pathogenesis and progression of immunoglobulin (Ig)A nephropathy (IgAN). Among these, we have selected C4d (complement lectin pathway involvement), CD3 (T cell marker, traducing interstitial inflammation), transglutaminase 2 (TGase-2, involved in tissue fibrosis development) and p-extracelluar-regulated kinase (ERK)1/2 (protein kinase intracellular signaling molecule) to perform a panel of immunohistological biomarkers and assess its predictive value for disease progression. Immunohistochemical staining of these biomarkers was performed in paraffin sections from 74 renal biopsy cases with the clinical diagnosis of IgAN. Association between score analysis of these parameters and disease course was assessed through univariate and multivariate analysis, including baseline clinical and histological data. Univariate analysis showed that glomerular C4d, tubulointerstitial TGase2 and CD3 scores were associated with baseline proteinuria and disease progression. Multivariate analysis showed that only baseline estimated glomerular filtration rate (eGFR), C4d and CD3 were associated independently with progressive kidney disease (decline of at least 50% in the eGFR or progression to end-stage renal disease (ESRD) during the follow-up period). Establishing an accurate prediction model for IgAN progression is still a matter of research in clinical nephrology. The complement system, particularly lectin pathway activation, and T cell activation, have been shown previously to be potential modifiers of the disease course. Here we show that the combination of two histological biomarkers (C4d and CD3) can be a powerful predictor of IgAN progression and a potential useful tool for the clinical approach of this disease.

Collagen type IV-related nephropathies in Portugal: pathogenic COL4A5 mutations and clinical characterization of 22 families

Alport syndrome (AS) is caused by pathogenic mutations in the genes encoding α3, α4 or α5 chains of collagen IV (COL4A3/COL4A4/COL4A5), resulting in hematuria, chronic renal failure (CRF), sensorineural hearing loss (SNHL) and ocular abnormalities. Mutations in the X-linked COL4A5 gene have been identified in 85% of the families (XLAS). In this study, 22 of 60 probands (37%) of unrelated Portuguese families, with clinical diagnosis of AS and no evidence of autosomal inheritance, had pathogenic COL4A5 mutations detected by Sanger sequencing and/or multiplex-ligation probe amplification, of which 12 (57%) are novel. Males had more severe and earlier renal and extrarenal complications, but microscopic hematuria was a constant finding irrespective of gender. Nonsense and splice site mutations, as well as small and large deletions, were associated with younger age of onset of SNHL in males, and with higher risk of CRF and SNHL in females. Pathogenic COL4A3 or COL4A4 mutations were subsequently identified in more than half of the families without a pathogenic mutation in COL4A5. The lower than expected prevalence of XLAS in Portuguese families warrants the use of next-generation sequencing for simultaneous COL4A3/COL4A4/COL4A5 analysis, as first-tier approach to the genetic diagnosis of collagen type IV-related nephropathies.