The amount of liver tissue is essential for accurate histological staging in patients with autoimmune hepatitis

The gold standard for the evaluation of liver fibrosis is histology. However, the heterogenous distribution of fibrosis limits the sensitivity of histology. The collection of two samples with a 16G needle is therefore recommended to reduce the risk of sampling error. The aim of this study was to investigate whether this standard is also applicable to patients with autoimmune hepatitis (AIH). This retrospective study included patients with AIH, who underwent mini-laparoscopic biopsy at our center between 2011 and 2020 (n = 32). Diagnosis was verified by usage of the simplified AIH score (≥ 6). Patients were categorized into three groups, based on the number of portal fields (PF) in the collected liver tissue (< 10 PF, 10 - 19 PF, ≥ 20 PF). We correlated the histological staging for these groups with the mini-laparoscopic fibrosis score (MLFS). Furthermore, non-invasive methods for the assessment of fibrosis were correlated with the histological staging (acoustic radiation force impulse (ARFI) and FIB-4 score). MLFS correlated well with histological staging (r = 0.649, p = 0.0001). The correlation between MLFS and histology improved with higher numbers of histologically analyzed portal fields (< 10 PF: r = 0.400, p = 0.378; 10 - 19 PF: r = 0.5467, p = 0.023; ≥ 20 PF: r = 0.956, p = 0.0002). The probability of collecting at least 10 or 20 portal fields was dependent on the number and diameter of the samples. For all patients with at least two 16G biopsies, 10 or more PF were available. With three 16G biopsies, at least 20 PF were obtained for all patients. ARFI correlated with MLFS and histological staging only in patients with low/moderate-grade inflammation as defined by ALT < 10xULN (upper limit of normal) (MLFS: r = 0.723; p = 0.004; histology: r = 0.619, p = 0.018). FIB-4 did not correlate with histological staging. The amount of liver tissue obtained by liver biopsy is crucial to minimalize the risk of sampling error and thus underestimation of fibrosis. This study was the first to investigate the amount of liver tissue required for histological staging in AIH. Our data suggest that diagnostic accuracy is likely to be higher with 20 PF compared to the generally recommended 10 PF. We therefore recommend to perform three biopsies with a 16G needle in (suspected) AIH patients. ARFI correlated well with histological staging unless inflammatory activity is high.

164 Gonadotrophin-releasing hormone injection and colour flow Doppler ultrasound of the preovulatory follicle as a tool to increase pregnancy outcome after timed AI in beef cows

The aims of this study were to determine (1) the association between Doppler vascularisation scores (DVS) of the preovulatory follicle (POF) and fertility of beef cows submitted to timed AI (TAI) and (2) whether cows with low DVS benefit from a gonadotrophin-releasing hormone (GnRH) treatment at TAI. Multiparous lactating Nelore cows (Bos indicus; n=69) from a commercial beef farm in the state of Rondônia, Brazil, were enrolled in this study. Cows received 2mg of oestradiol benzoate intramuscularly (Bioestrogen, Biogénesis Bagó) and an intravaginal progesterone-releasing device (1.9g of progesterone; controlled internal drug release, CIDR) to synchronise follicular wave emergence on Day 0. The CIDR device was removed and cows were treated with 150μg of D-cloprostenol intramuscularly (prostaglandin F2α analogue; Croniben), 1mg of oestradiol cypionate intramuscularly, and 300IU of equine chorionic gonadotrophin (Novormon) intramuscularly on Day 8. Cows were then painted with a tail chalk marker to identify those displaying oestrus. All cows were submitted to TAI 48h after CIDR removal. At TAI, occurrence of oestrus was recorded and all cows were examined using transrectal ultrasonography. Blood flow of the POF was evaluated using colour Doppler imaging. Colour Doppler signals present on the follicular wall were subjectively scored using a 1-to-4 scale (1=absence or very low blood flow, and 4=intense blood flow detected on most of the follicular wall surface) adapted from Ginther (2007Ultrasonic Imaging and Animal Reproduction: Color-Doppler Ultrasonography, pages 87-114). Then, cows were divided into three groups according their DVS of the POF: (1) high DVS (DVS ≥3; n=36), (2) low DVS (DVS &lt;3; n=16), and (3) low DVS (DVS &lt;3; n=17) plus a GnRH treatment at TAI. The diameter of the POF was analysed using analysis of variance (PROC GLIMMIX of SAS; SAS Institute Inc.), and the means were compared among groups using Tukey's test. The proportion of cows that displayed oestrus and pregnancy rates was analysed using chi-square test. Cows in the high-DVS group had a larger POF than cows in the low-DVS and low-DVS-GnRH groups (13.2±0.2, 11.7±0.5, and 12.2±0.4, respectively; P&lt;0.05). The proportion of cows that displayed oestrus was greater (P&lt;0.05) in the high-DVS group (72%, 26/36) than in the low-DVS (37.5%, 6/16) or low-DVS-GnRH (53%, 9/17) groups. Finally, greater (P&lt;0.05) pregnancy rates were observed in cows from the high-DVS (47.2%; 17/36) and low-DVS-GnRH (52.9%; 9/17) groups than in cows from the low-DVS group (18.7%; 3/16). The preliminary results from this study demonstrated that diameter of POF is positively associated with DVS. Moreover, cows that presented POF with higher DVS are more likely to become pregnant, and the administration of GnRH to females with low DVS can increase the fertility of beef cows submitted to TAI protocols. This study received funding support from Embrapa (MP1/PC3 project no. 01.03.14.011.00.00) and from CNPq (universal project no. 407307/2016-8).

LI-RADS-CEUS - Proposal for a Contrast-Enhanced Ultrasound Algorithm for the Diagnosis of Hepatocellular Carcinoma in High-Risk Populations

Purpose: To develop a contrast-enhanced ultrasound algorithm (LI-RADS-CEUS = liver imaging reporting and data system with contrast-enhanced ultrasound) for the diagnosis of hepatocellular carcinoma (HCC) in patients at risk. Materials and Methods: A CEUS algorithm (LI-RADS-CEUS) was designed analogously to CT- and MRI-based LI-RADS. LI-RADS-CEUS was evaluated retrospectively in 50 patients at risk with confirmed HCC or non-HCC lesions (test group) with subsequent validation in a prospective cohort of 50 patients (validation group). Results were compared to histology, CE-CT and CE-MRI as reference standards. Results: Tumor diagnosis in the test group/validation group (n = 50/50) were 46/41 HCCs, 3/3 intrahepatic cholangiocellular carcinomas (ICCs) and 1/6 benign lesions. The diagnostic accuracy of LI-RADS-CEUS for HCC, ICC and non-HCC-non-ICC-lesions was 89 %. For the diagnosis of HCC, the diagnostic accuracy was 93.5 % (43/46 cases) in the test group and 95.1 % (39/41 cases) in the validation group. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were 94.3 %, 66.6 %, 94.3 % and 66.6 %, respectively (mean values from both cohorts). Histological findings of HCC were available in 40 versus 23 cases (in total: G1 / G2/G3: 15/35/13). Arterial hyperenhancement was seen in 68/87 (78.2 %) of HCCs. Arterial hyperenhancement with subsequent portal venous or late phase hypoenhancement was seen in 66 % of HCCs. Conclusion: LI-RADS-CEUS offers a CEUS algorithm for standardized assessment and reporting of focal liver lesions in patients at risk for HCC. Arterial hyperenhancement in CEUS is the key feature for the diagnosis of HCC in patients at risk, whereas washout is not a necessary prerequisite.

Comparison of Acoustic Radiation Force Impulse (ARFI) Elastography Measurements with the 4C1 Transducer to the 6C1HD Transducer: A Phantom and Patient Study

Purpose: The aim of this study was to evaluate whether acoustic radiation force impulse (ARFI) elastography done with the 4C1 probe yields comparable results to the recently introduced 6C1HD probe. Materials and Methods: Measurements with the 4C1 and 6C1HD probes (Acuson S2000) were performed and compared in four different inclusions of an elasticity phantom model (QA049 CIRS) as well as in the liver of healthy individuals and patients with liver cirrhosis. Results: Measurements with the 6C1HD probe were slightly higher in all phantom inclusions (8, 14, 45, 80kPA) with a mean of 1.48 m/s (95 %-CI; 1.47 - 1.49), 2.18 m/s (95 %-CI; 2.17 - 2.19), 3.61 m/s (95 %-CI; 3.57 - 3.64) and 4.34 m/s (95 %-CI; 4.29 - 4.39) compared to the 4C1 transducer with 1.46 m/s (95 %-CI; 1.45 - 1.47), 2.15 m/s (95 %-CI; 2.14 - 2.16), 3.39 m/s (95 %-CI; 3.37 - 3.41) and 3.98 m/s (95 %-CI; 3.75 - 4.21), respectively (p = 0.04, p < 0.01, p < 0.01, p < 0.01). Cirrhotic patients (n = 40) had a higher mean shear wave speed with 3.00 m/s (95 %-CI; 2.80 - 3.21) with the 6C1HD transducer compared to 2.81 m/s (95 %-CI; 2.64 - 2.99) with the 4C1 transducer (p = 0.03). Healthy individuals (n = 20) had a mean shear wave speed of 1.12 m/s (95 %-CI; 1.06 - 1.17) with the 6C1HD probe and 1.12 m/s (95 %-CI; 1.05 - 1.19) with the 4C1 probe (p = 0.96). Conclusion: ARFI values assessed with a 6C1HD transducer are slightly higher than measurements with a 4C1 transducer in an ARFI phantom and in patients with liver cirrhosis. As the difference is small, current cut-off values keep their usefulness but should be interpreted with caution if measurements are close to the cut-off.

Prospective Evaluation of Acoustic Radiation Force Impulse (ARFI) Elastography and High-Frequency B-Mode Ultrasound in Compensated Patients for the Diagnosis of Liver Fibrosis/Cirrhosis in Comparison to Mini-Laparoscopic Biopsy

PURPOSE

Ultrasound is a well-established noninvasive test for assessing patients with liver disease. This study aims to prospectively compare ultrasound to the new technique elastography (ARFI) for the assessment of liver fibrosis/cirrhosis.

MATERIALS AND METHODS

High-frequency B-mode ultrasound (liver surface/vein irregularity, liver homogeneity, spleen size), ARFI quantification, mini-laparoscopic liver evaluation including biopsy were prospectively obtained in compensated patients scheduled for liver biopsy. For the diagnosis of cirrhosis, a combined gold standard (cirrhosis at histology and/or at macroscopic liver evaluation) was used.

RESULTS

Out of 157 patients, 35 patients were diagnosed cirrhotic. Ultrasound (combination of liver vein and/or surface irregularity) showed no significant difference compared to ARFI quantification for the diagnosis of significant liver fibrosis (Ishak> = 3) and cirrhosis. Diagnosis of cirrhosis had a sensitivity/specificity/PPV/NPV of 83 %(± 12) / 82 %(± 7) / 57 %(± 14) / 94 %(± 4), respectively, with ultrasound and 86 %(± 12) / 81 %(± 7) / 57 %(± 13) / 95 %(± 4), respectively, with ARFI quantification. The sensitivity/specificity/PPV/NPV for the detection of significant fibrosis were 68 %(± 13) / 86 %(± 7) / 71 %(± 13) / 84 %(± 7), respectively, for ultrasound and 70 %(± 12) / 84 %(± 7) / 69 %(± 12) / 84 %(± 7), respectively, for ARFI quantification.

CONCLUSION

ARFI elastography and high-frequency B-mode ultrasound show similar and good results for the diagnosis of compensated liver cirrhosis and high-grade fibrosis. A key benefit of both methods is the high NPV suggesting them as noninvasive exclusion tests.

Quantitative perfusion analysis in pancreatic contrast enhanced ultrasound (DCE-US): a promising tool for the differentiation between autoimmune pancreatitis and pancreatic cancer

In the work-up of focal pancreatic lesions autoimmune pancreatitis (AIP) is a rare differential diagnosis to pancreatic cancer (PC) with similar clinical constellations. The aim of our study was to compare differences between proven AIP and PC using transabdominal dynamic contrast enhanced ultrasound (DCE-US). Therefore we recorded 3-minute-clips of CEUS examinations and analyzed perfusion parameters with VueBox®-quantification software. To obtain DCE-US Parameters, Regions-of-Interest were selected within the lesions and the surrounding pancreas parenchyma, serving as reference tissue. We compared 3 patients with AIP (mean age: 58 years; lesion mean size: 40 mm) to 17 patients with PC (mean age: 68 years; lesion mean size: 35.9 mm). Significant differences between PC and parenchyma could be found in the following parameters: Peak-Enhancement (PE), Wash-in-and-Wash-out-AUC, Wash-in Perfusion-Index. PE of AIP was comparable to normal parenchyma. The relation of PE between parenchyma and lesion (ΔPE) AIP and PC was significantly different [AIP: 0.21 (±0.06); PC: 0.81 (±0.1); p<0.01]. PE of neoplastic lesions was significantly lower as AIP and normal parenchyma (p<0.01). Therefore perfusion analysis in DCE-US can help to differentiate hypovascular PC from AIP presenting nearly isovascular time intensity curves. Diagnostic accuracy of DCE-US in this setting has to be validated in future prospective studies in comparison to CT and MRI.

Dynamic contrast-enhanced ultrasound (DCE-US) for the characterization of hepatocellular carcinoma and cholangiocellular carcinoma

PURPOSE

In a prospective study, we compared the different perfusion kinetics of HCC and ICC using dynamic contrast-enhanced ultrasound (DCE-US).

MATERIALS AND METHODS

Patients with proven HCC and ICC were included. Three-minute video clips of CEUS examinations (CPS - low MI mode) after a bolus injection of 1.2 ml SonoVue were recorded and analyzed with quantification software (VueBox). Parameters for the arterial contrast enhancement [rise time (RT), time-to-peak (TTP)] towards portal venous contrast enhancement [mean transit time (local) (mTTl) and fall time (FT)] were quantified. Furthermore, contrast wash-out after peak enhancement (PE) (40 s, 80 s, 100 s and 120 s after PE) was compared between HCC and ICC.

RESULTS

43 patients with proven HCC (n = 23 HCC; cirrhosis n = 16) and ICC (n = 20 ICC; Cirrhosis n = 6) were examined. No statistical difference of the arterial DCEUS parameters was found between HCC and ICC. Contrast enhancement of the portal venous and late phases showed significantly lower values in the ICC group indicating early wash-out of the contrast agent: mTTl (p = 0.0209): HCC 118.4 s (SD± 88.4); ICC 64.8 s (SD± 49.7). FT (p = 0.0433): HCC 42.5 s (SD± 27.7); ICC 27.7 s (SD± 16.2). The percental loss of intensity at a definite time point after PE was significantly higher in ICC than in HCC lesions.

CONCLUSION

DCE-US is able to detect and quantify differences in perfusion kinetics between HCC and ICC. Whereas arterial contrast enhancement patterns may overlap between HCC and ICC, a timed characterization of wash-out kinetics may offer an additional tool to characterize HCC and ICC. The presence of a rapid loss of signal intensity in the early portal venous phase is significantly higher in ICC than in HCC lesions.

Liver stiffness assessed by acoustic radiation force impulse (ARFI) technology is considerably increased in patients with cholestasis

PURPOSE

To explore the impact of cholestasis on liver stiffness assessed by acoustic radiation force impulse (ARFI) technology.

MATERIALS AND METHODS

Over a period of four months, patients with sonographic cholestasis and increased cholestatic blood values (Bilirubin, γGT, AP > 2 times ULN) scheduled for endoscopic therapy were recruited. Exclusion criteria were: known liver disease; signs of cirrhosis at ultrasound (irregular liver veins and/or surface); heart insufficiency (NYHA III-VI). ARFI (Siemens S2000), ultrasound and blood examinations were performed before and in a subgroup after successful biliary drainage.

RESULTS

In total, 21 patients with cholestasis were included in the study. ARFI measurements were above the cut-off for cirrhosis (1.8  m/s) in all patients with a mean of 2.91  m/s ± 0.89  m/s without a history or signs of cirrhosis. Bilirubin, γGT and AP were elevated on average to 9.7 ± 5.3  mg/dl, 1192 ± 960  U/l and 730 ± 389  U/l. A subgroup of 10 patients was measured after successful drainage. ARFI measurements declined in all patients of that subgroup on average by 0.76  m/s at a mean time interval of 4.5 days (p < 0.001).

CONCLUSION

Cholestasis significantly increases liver stiffness assessed by ARFI. Therefore, it is important to exclude profound cholestasis when using ARFI for evaluating patients for liver fibrosis.

Acoustic radiation force impulse (ARFI) and high-frequency ultrasound of the liver surface for the diagnosis of compensated liver cirrhosis

PURPOSE

To evaluate the diagnostic value of acoustic radiation force impulse (ARFI) and high-frequency ultrasound of the liver surface, using histology as a gold standard for the diagnosis of compensated liver cirrhosis.

MATERIALS AND METHODS

73 patients without ascites undergoing liver biopsy were included in the study. The left and right liver lobes were examined with ARFI and high-frequency ultrasound. Liver surface irregularity was quantified using image analysis software to calculate the difference between the real surface and the approximated physiological surface through a 20 mm standardized line.

RESULTS

There is a significant difference between cirrhotic and non-cirrhotic patients for both quantified liver surface (QLS) and ARFI (p < 0.001). The mean values for QLS of the left lobe were 0.71 ± 0.24 mm and 1.17 ± 0.80 mm, of the right lobe 0.56 ± 0.26 mm and 0.87 ± 0.26 mm for non-cirrhotic and cirrhotic patients, respectively. The mean values of ARFI measurements of the left lobe were 2.04 ± 0.76 m/s and 2.85 ± 0.81 m/s, of the right lobe 1.65 ± 0.61 m/s and 3.02 ± 0.77 m/s for non-cirrhotic and cirrhotic patients, respectively. Diagnostic accuracy (AUROC) was 0.78/0.80 for QLS and 0.77/0.91 for ARFI of the left/right lobe, respectively. ARFI of the right lobe is significantly better than ARFI of the left (p = 0.023) or QLS of the left (p = 0.025)/right (p = 0.046) lobe of the liver.

CONCLUSION

Assessment of liver surface irregularity by high-frequency ultrasound (QLS) is a useful diagnostic test for the assessment of compensated liver cirrhosis. ARFI of the right liver lobe is significantly better than high-frequency ultrasound (QLS of the left/right lobe of the liver) and ARFI of the left lobe of the liver.

20 ADMINISTRATION OF FOLLICLE-STIMULATING HORMONE AT CIDR REMOVAL DOES NOT AFFECT THE PREGNANCY RATE IN A CIDR-BASED, COSYNCH PROTOCOL IN LACTATING BEEF COWS

In previous studies, giving eCG at CIDR removal significantly increased the pregnancy rate after timed-AI in beef cows. However, eCG is not universally available. Therefore, we tested the hypothesis that giving pFSH at CIDR removal might improve the pregnancy rate in a CIDR-based, Cosynch protocol in postpartum, suckled Bos taurus beef cows; a secondary objective was to compare pregnancy rates when GnRH v. pLH was used to synchronize wave emergence and ovulation. This work was conducted as two experiments (separate locations). All cows were given a CIDR (containing 1.9 g progesterone; Pfizer Animal Health, Montreal, QC, Canada) on Day 0 (without regard to stage of estrous cycle or cyclicity). On Day 7, CIDRs were removed, all cows were concurrently given 25 mg PGF (Lutalyse; Pfizer Animal Health, Groton, CT, USA), half were given 20 mg pFSH (Folltropin-V; Bioniche Animal Health, Belleville, ON, Canada), and all cows were timed-AI 54 h later (Day 9). In Experiment 1, 240 cows [94 � 10.8 days postpartum; body condition score (BCS: 1 = emaciated, 9 = obese; mean � SD): 5.8 � 0.4] were used; at CIDR insertion and AI, cows were allocated to receive either 100 µg GnRH (n = 160; Cystorelin, Merial Canada Inc., Victoriaville, QC, Canada) or 12.5 mg pLH (n = 80; Lutropin-V, Bioniche Animal Health). In Experiment 2, 109 cows (59.2 � 19.5 days postpartum; BCS: 5.6 � 1.1) were used; all received 100 µg GnRH (Cystorelin) at CIDR insertion and AI. In Experiment 1, three cows that lost their CIDR were excluded; pregnancy rates after timed-AI (logistic regression, backward selection: parity, pFSH, synchronizing treatment, and their interactions) were not different between cows given pFSH v. control cows (64.7 v. 65.2%; P > 0.80), nor between cows given GnRH v. pLH (62.7 v. 69.6%; P = 0.91). However, there was an interaction (P < 0.04) between parity and the synchronizing treatment; in primiparous cows, pregnancy rates were significantly lower in those given GnRH v. pLH (59.3 v. 83.3%). In Experiment 2, pregnancy rates after timed-AI (logistic regression, backward selection: parity, pFSH, and their interaction) were not different between cows given pFSH v. control cows (38.2 v. 42.6%; P > 0.6). In conclusion, our hypothesis was not supported; giving pFSH at CIDR removal did not significantly improve the pregnancy rate in a CIDR-based, Cosynch protocol in postpartum, suckled Bos taurus beef cows.

Determination of NADH in frozen rat brain sections by laser-induced fluorescence

Methods to assess metabolism are important analytical tools in neuroscience. The fluorophore nicotinamide adenine dinucleotide (NADH) is a parameter of cellular metabolism. NADH fluorescence was measured using a laser-based fluorescence detector with spectral and temporal filters. Distribution and intensity of NADH fluorescence were investigated in frozen brain sections. In sections containing hippocampus the intensity of NADH fluorescence was correlated to brain structures. In order to investigate the consequences of neurotoxic lesions, 5,7-dihydroxytryptamine was injected into the dorsal raphe nucleus 4 to 240 days prior to the measurement. NADH fluorescence decreased in the affected region by 50%, indicating that no recovery in metabolic activity had occurred.

Cortical NADH during pharmacological manipulations of the respiratory chain and spreading depression in vivo

The nicotinamide adenine dinucleotide (NADH) is one of the main means for energy transfer in the mitochondrial respiratory chain and is an important parameter of cellular metabolism. NADH can be measured by its fluorescence and various fluorometric methods have been developed. In this study, a pulsed nitrogen laser combined with a fibreoptic set-up and photomultipliers was used to induce and measure NADH fluorescence on the cortical surface. The aim of the study was to assess the suitability of the laser induced spectroscopy for in vivo and on-line measurement of NADH in neuroscience and particularly for the assessment of neuronal metabolism. Changes in cerebral blood flow may affect fluorescence measurement. To assess the consequences of alterations in blood flow, the vasodilators glyceryl trinitrate and nimodipine and the vasoconstrictor endothelin-1 were applied. The induced hemodynamic changes were verified by colour Doppler sonography. The tests using the vasodilators showed that an increased blood flow in the brain increased not only NADH fluorescence but also the scattered light measured. The vasoconstrictor caused opposite effects. Insertion of a compensation method (subtraction of the scattered light) allowed the exclusion of hemodynamic artifacts. Effects of changes in the cellular metabolism were induced by sodium cyanide, an inhibitor of the mitochondrial respiratory chain, or by 2,4-dinitrophenol (2,4-DNP), an uncoupler of the oxidative phosphorylation. Sodium cyanide induced a transient increase of NADH fluorescence and 2,4-DNP decreased intracellular NADH fluorescence. Furthermore, the repercussions of cortical spreading depressions (CSD), a response of the brain to noxious stimuli, on cortical NADH fluorescence were determined. A single CSD decreased cortical NADH fluorescence for about 1 min, followed by a 5- to 10-min increase. The changes in NADH levels seem to correspond with the excitation and inhibition of neuronal metabolism, respectively. In summary, the measurement of NADH fluorescence using the laser technique allows the determination of changes in oxidative phosphorylation with high regional selectivity and time resolution.

Beckwith-Wiedemann syndrome: difficulties with prenatal diagnosis

Beckwith-Wiedemann syndrome (BWS), though a well-delineated clinical and morphological entity, can be difficult to diagnose by prenatal ultrasound examination when incomplete forms occur. We present a case with sonographic results including hydronephrosis, cardiomegalia, hepatomegalia, macroglossia, and prominent forehead. No abdominal wall defect was detected. Karyotype was normal. In spite of intensive prenatal diagnostics, BWS could not be diagnosed definitely until birth.

Prenatal diagnosis of the acute form of proximal spinal muscular atrophy: experience on the acceptance of linkage analyses by the families

The acute form of proximal spinal muscular atrophy (SMA) is a severe autosomal recessive inherited neuromuscular disorder. It has been mapped to chromosome 5q 11.2-13.3. Using restriction fragment length polymorphisms (RFLPs) or (CA)n repeats of DNA probes in this region, prenatal diagnosis is, in principle, possible. Misdiagnosis can be due to incorrect diagnosis in the index patient, and crossing-over events. Using the DNA probes D5S6, D5S112, D5S39, and D5S78, we cover a region of 10.4 mega-base pairs (Mbp) of partially NotI-digested genomic DNA without overlap of fragments. The DNA probes D5S6 and D5S112, most likely flanking the SMA gene, cover a distance of about 6.6 Mbp. This corresponds to the genetic distance of 6 cM (Morrison et al., 1992; Daniels et al., 1992). But since the precise localization of the SMA gene is still unknown (Simard et al., 1992), a 10 per cent risk of misdiagnoses due to crossing-over events cannot be excluded. The acceptance of this 10 per cent risk for prenatal diagnoses differs in SMA families. We observed a case in which a woman accepted a 25 per cent risk because RFLPs and (CA)n repeats were both uninformative. In contrast, another family did not accept the minimal 10 per cent risk and the pregnancy was terminated. In two families, we performed prenatal diagnosis by linkage analysis. One child predicted to be healthy has been born in the meantime and has shown no indication of SMA during her first 8 months.