Next-generation sequencing of uveal melanoma with clinical and histological correlations: Prognostic value of new mutations in the PI3K/AKT/mTOR pathway.

BACKGROUND: Uveal melanoma (UM) is the eye's most common primary malignancy and there are no effective therapies for disseminated disease. It is important to try to know the patient's prognosis. The aim of this study was to reflect genetic variants, studied using NGS, of a series of 69 cases of UM and its correlation with histopathology and clinical progression. METHODS: We performed targeted NGS using a 519-gene panel. RESULTS: There were selected 28 different mutated genes, showing a total of 231 genetic variants that affected the function of the protein. The most common secondary mutations occurred in SF3B1 (in 26%), followed by BAP1 (in 23%), LRP1B (22%) and FGFR4 (20%). BAP1 mutation was associated with a greater likelihood of metastases and with greater presence of epithelioid cells. LRP1B was also associated with presence of epithelioid cells SF3B1 mutation was significantly associated with a spindle morphology. We found variants in the RAD51B, TOP2A, PTPRD, TSC2, DHX9, PDK1 and MTOR that have not been previously reported in consulted databases. The presence of a mutation in: CHEK2, DHX9 and PDK1 was associated with metastases. CONCLUSIONS: BAP1 is the most solid biomarker of a poor prognosis in UM and mutations can be detected using NGS. SF3B1 is associated with the spindle cell subtype of UM, which gives it probably a favourable prognostic value. Our study suggests that mutations in DHX9 and PDK1 can have prognostic value. These potential biomarkers are related to the PI3K/AKT/mTOR pathway and makes them candidates for developing new directed therapies.

From unknown to known: Identification of the remains at the mausoleum of fosse Ardeatine.

During the Second World War, on 24th March 1944, 335 Italians were massacred near Rome by the occupying forces of Nazi Germany. Four months later forensic examination led to the identification of 323 out of 335 victims. After approximately 60 years, the identification of the remaining unidentified twelve victims began with anthropological and genetic analysis carried out by a team of Italian forensic experts. Anthropological analysis was performed in field in order to confirm the sex of each victim and verify the presence of only one individual in each grave for a correct sampling. Selected bone fragments for each individual were then collected and transferred to the laboratory for genetic analysis. Although the anthropological ante mortem information was limited, morphological and metrical data was collected for a possible future identification of the victims. Subsequently, the typing of autosomal loci, Y-STR and mtDNA D-loop region of all bone and available reference samples was conducted. LR and cumulative LRs obtained from autosomal STR and Y-STR results confirmed the alleged relationship between three victims and their relatives with values over 104 (one sample) and 106 (two samples). Therefore, the genetic analysis offered the families the possibility of replacing the number of the grave with the name of the victim.

Preliminary assessment of the prototype Yfiler® Plus kit in a population study of Northern Italian males.

A total of 150 samples of unrelated males from North of Italy were analyzed with the prototype Yfiler® Plus kit (Thermo Fisher Scientific, Oyster Point, CA). This kit is a short tandem repeat (STR) assay based on six-dye chemistry that amplifies 25 Y-STR loci. Sixteen loci are in common with Yfiler® kit and nine are new (DYS576, DYS627, DYS460, DYS518, DYS570, DYS449, DYS481, DYF387S1a/b, DYS533). In this population study, the improvement of adding additional Y-STR markers increased the discriminatory capacity from 0.787 with the minimum haplotype (MHT) loci to 1 with the prototype Yfiler® Plus kit.

Intravascular lithotripsy (IVL) enabled the percutaneous closure of a severely calcified paravalvular leak regurgitation following implantation of a self-expandable transcatheter aortic valve: a case report.

Background: Closure of paravalvular leak (PVL) regurgitation after self-expandable (SE) transcatheter aortic valve implantation (TAVI) may be more challenging than after balloon-expandable (BE) valve implantation. Case summary: An 85-year-old woman suffering from long-standing atrial fibrillation and severe symptomatic aortic stenosis underwent SE TAVI (26 mm Evolut™ R®, Medtronic Inc., MN, USA). A total of eighteen months after TAVI she was admitted for congestive heart failure and two-dimensional (2D) transesophageal echocardiography (TEE) color Doppler showed moderate-severe PVL regurgitation due to a long and heavily calcified leak located below the left coronary sinus. The patient was deemed to be at prohibitive surgical risk and a catheter-based PVL closure procedure was planned. A first attempt to cross the PVL from the femoral artery was unsuccessful due to an inappropriate angle between the catheter and the entry site of this hard-to-approach calcified leak. A Terumo hydrophilic guidewire 0.35 inch-260 cm from the right radial artery was then successfully advanced across the leak to the left ventricle (LV); however, of most of the catheters used, only a Glidecath 4-Fr could cross the leak over the hydrophilic wire. The hydrophilic guidewire was replaced with a stiffer guidewire that, after creating a loop in the LV, was advanced across the self-expandable valve into the descending aorta where it was snared and externalized through the left femoral artery, thus creating an arterio-arterial (AA) loop. A 6-Fr Multipurpose guiding catheter was advanced over the exchange wire and the leak was crossed with an additional 0.0014 coronary guidewire (PILOT, Abbott Vascular), predilated with two non-compliant balloon dilatation catheters, and finally, the PVL was engaged with a 3.0 mm × 12 mm Shockwave balloon (Shockwave Medical Inc, Santa Clara, California, USA). Intravascular lithotripsy (IVL) application to this highly calcified leak and the increased support provided by the stiff guidewire finally allowed the progression of the 6-Fr dedicated delivery sheath (ODS III) into the LV. A 5 mm square twist (ST) device (PLD, Occlutech, Helsingborg, Sweden) was successfully deployed within the leak and the final echocardiographic and angiographic control confirmed the effective PVL closure. Discussion: In patients at high surgical risk with moderate to severe regurgitation after SE TAVI due to a hard-to-approach calcified long tract, an extra AA support loop is mandatory during percutaneous PVL closure. Furthermore, IVL application greatly facilitates the progression of the delivery sheath and occluder which is key to a successful procedure.

Kidney Injury After Minimal Radiographic Contrast Administration in Patients With Acute Coronary Syndromes.

BACKGROUND: Acute kidney injury (AKI) is common in patients with acute coronary syndromes (ACS) treated by percutaneous coronary intervention. OBJECTIVES: Contrast media (CM) volume minimization has been advocated for prevention of AKI. The DyeVert CM diversion system (Osprey Medical, Inc) is designed to reduce CM volume during coronary procedures. METHODS: In this randomized, single-blind, investigator-driven clinical trial conducted in 4 Italian centers from February 4, 2020 to September 13, 2022, 550 participants with ACS were randomly assigned in a 1:1 ratio to the following: 1) the contrast volume reduction (CVR) group (n = 276), in which CM injection was handled by the CM diversion system; and 2) the control group (n = 274), in which a conventional manual or automatic injection syringe was used. The primary endpoint was the rate of AKI, defined as a serum creatinine (sCr) increase ≥0.3 mg/dL within 48 hours after CM exposure. RESULTS: There were 412 of 550 (74.5%) participants with ST-segment elevation myocardial infarction (211 of 276 [76.4%] in the CVR group and 201 of 274 [73.3%] in the control group). The CM volume was lower in the CVR group (95 ± 30 mL vs 160 ± 23 mL; P < 0.001). Seven participants (1 in the CVR group and 6 in the control group) did not have postprocedural sCr values. AKI occurred in 44 of 275 (16%) participants in the CVR group and in 65 of 268 (24.3%) participants in the control group (relative risk: 0.66; 95% CI: 0.47-0.93; P = 0.018). CONCLUSIONS: CM volume reduction obtained using the CM diversion system is effective for prevention of AKI in patients with ACS undergoing invasive procedures. (REnal Insufficiency Following Contrast MEDIA Administration TriaL IV [REMEDIALIV]: NCT04714736).

The impact of coronavirus disease 2019 on acute coronary syndrome: Differences between epidemic waves.

Introduction: Since the beginning of the COronaVIrus Disease 2019 (COVID-19) pandemic, poor attention has been paid to the indirect effects of the pandemia on cardiovascular health system, in particular in patients with Acute Coronary Syndrome (ACS). The aims of this study is to compare possible epidemiological, clinical and management differences between the four epidemic waves in groups of patients hospitalized for ACS with a view to highlighting the burden of the pandemic on the management of this syndrome. Materials and methods: In this retrospective observational study we included 98 patients admitted to Coronary Intensive Care Unit (CICU) for ACS between March 2020 and March 2022, who underwent revascularization procedure using percutaneous coronary angioplasty (PCI). The patients examined were divided into four groups representative of the four epidemic waves that affected our country. Results: The rate of hospitalization for ACS increased progressively to a 178 % increase in the third wave compared to the first (p = 0.003), with an increase of 900 % if we consider only Non-ST-Elevation Myocardial Infarction (NSTEMI) (representing 54 % of the ACS diagnoses of the third group against 14.3 % in the first). Longer door-to-balloon times were recorded in the third wave for the increased presence of NSTEMI. The average hospital stay was lower in the third wave with 5 ± 2 days (p = 0.007) as well as mortality (5.1 % in the third wave; the highest in the fourth wave with 9.5 %). Conclusions: The study show that the management of ACS suffered most from the indirect effects of the pandemic during the first wave, both because of the unpreparedness of hospital facilities and because of the fear of infection that has dissuaded people from asking for help.

Role of Lipoprotein Ratios and Remnant Cholesterol in Patients with Myocardial Infarction with Non-Obstructive Coronary Arteries (MINOCA).

BACKGROUND: Myocardial infarction with non-obstructive coronary arteries (MINOCA) is a clinical situation characterized by evidence of acute myocardial infarction (AMI)-according to the Fourth Universal Definition of Myocardial Infarction-with normal or near-normal coronary arteries on angiographic study (stenosis < 50%). This condition is extremely variable in etiology, pathogenic mechanisms, clinical manifestations, prognosis and consequently therapeutic approach. OBJECTIVE: The objective of the study was the evaluation of remnant cholesterol (RC), monocyte/high-density lipoprotein cholesterol ratio (MHR), platelet/lymphocyte ratio (PLR) and various lipoprotein ratios in patients with MINOCA in order to establish their validity as predictors of this event. MATERIALS AND METHODS: We included 114 patients hospitalized in the Intensive Coronary Care Unit (ICCU) and Hospital Wards of our Hospital Center from 2015 to 2019 who received a diagnosis of MINOCA compared to a control group of 110 patients without previous cardiovascular events. RC was calculated with the following formula: RC = total cholesterol (TC) - HDL-C - LDL-C. MHR was calculated by dividing the monocyte count in peripheral blood by high-density lipoprotein cholesterol (HDL-C) levels; PLR was obtained by dividing platelet count by lymphocyte count. We also calculated various lipoprotein ratios, like total cholesterol/high-density lipoprotein cholesterol (TC/HDL-C), low-density lipoprotein cholesterol/high-density lipoprotein cholesterol (LDL-C/HDL-C), triglycerides/high-density lipoprotein cholesterol (TG/HDL-C), and non-high-density lipoprotein cholesterol/high-density lipoprotein cholesterol (non-HDL-C/HDL-C) ratios. RESULTS: The MINOCA group had higher mean levels of RC (21.3 ± 10.6 vs. 13.2 ± 7.7 mg/dL), MHR (23 ± 0.009 vs. 18.5± 8.3) and PLR (179.8 ± 246.1 vs. 135 ± 64.7) than the control group. Only the mean values of all calculated lipoprotein ratios were lower in MINOCA patients. Statistical significance was achieved only in the RC evaluation. CONCLUSIONS: Higher levels of RC and MHR were found in patients with MINOCA. We also observed higher levels of PLR than in the control group. Only various lipoprotein ratios were lower, but this could reflect the extreme heterogeneity underlying the pathogenic mechanisms of MINOCA. In patients who receive a diagnosis of MINOCA with a baseline alteration of the lipid profile and higher levels of cholesterol at admission as well, the evaluation of these parameters could play an important role, providing more detailed information about their cardiometabolic risk.

Longitudinal Strain Analysis and Correlation with TIMI Frame Count in Patients with Ischemia with No Obstructive Coronary Artery (INOCA) and Microvascular Angina (MVA).

Background: The aim of the study is to evaluate the subclinical alterations of cardiac mechanics detected using speckle-tracking echocardiography and compare these data with the coronary angiography indices used during coronary angiography in a population of patients diagnosed with ischemia with no obstructive coronary artery (INOCA) and microvascular angina (MVA). Methods: The study included 85 patients admitted to our center between November 2019 and January 2022 who were diagnosed with INOCA compared with a control group of 70 healthy patients. A collection of anamnestic data and a complete cardiovascular physical examination, and echocardiogram at rest with longitudinal strain were performed for all patients. Furthermore, the TIMI frame count (TFC) for the three coronary vessels was calculated according to Gibson's indications. All parameters were compared with a control population with similar characteristics. Results: Patients with INOCA compared to the control population showed statistically significant changes in the parameters assessed on the longitudinal strain analysis. In particular, patients with INOCA showed statistically significant changes in GLS (-16.71) compared to the control population (-19.64) (p = 0.003). In patients with INOCA, the total TIMI frame count (tTFC) correlated with the GLS value with a correlation coefficient of 0.418 (p = 0.021). Conclusions: In patients with angina, documented myocardial ischemia, the absence of angiographically significant stenosis (INOCA) and LVEF > 50%, the prevalence of microvascular dysfunction documented by TFC was extremely represented. A statistically significant reduction in GLS was observed in these patients. TFC and longitudinal strain, therefore, appear to be two reliable, sensitive and easily accessible methods for the study of alterations in coronary microcirculation and the characterization of patients with INOCA and microvascular angina.

Clinical Outcomes and Quality of Life after Patent Foramen Ovale (PFO) Closure in Patients with Stroke/Transient Ischemic Attack of Undetermined Cause and Other PFO-Associated Clinical Conditions: A Single-Center Experience.

INTRODUCTION: The aim of this study was to assess clinical outcomes and quality of life after PFO closure in patients with previous stroke/TIA of undetermined cause and in patients with other complex PFO-associated clinical conditions. METHODS: Between July 2009 and December 2019 at our University Cardiology Department, 118 consecutive patients underwent a thorough diagnostic work-up including standardized history taking, clinical evaluation, full neurological examination, screening for thrombophilia, brain magnetic resonance imaging (MRI), ultrasound-Doppler sonography of supra-aortic vessels and 24 h ECG Holter monitoring. Anatomo-morphological evaluation using 2D transthoracic/transesophageal echocardiography (TTE/TEE) color Doppler and functional assessment using contrast TTE (cTTE) in the apical four-chamber view and contrast transcranial Doppler (cTCD) using power M-mode modality were performed to verify the presence, location and amount of right-to-left shunting via PFO or other extracardiac source. Completed questionnaires based on the Quality-of-Life Short Form-36 (QoL SF-36) and Migraine Disability Assessment (MIDAS) were obtained from the patients before PFO closure and after 12 months. Contrast TTE/TEE and cTCD were performed at dismission, 1, 6 and 12 months and yearly thereafter. Brain MRI was performed at 1-year follow-up in 54 patients. RESULTS: Transcatheter PFO closure was performed in 106 selected symptomatic patients (mean age 41.7 ± 10.7 years, range 16-63, 65% women) with the following conditions: ischemic stroke (n = 23), transient ischemic attack (n = 22), peripheral and coronary embolism (n = 2), MRI lesions without cerebrovascular clinical events (n = 53), platypnea-orthodeoxia (n = 1), decompression sickness (n = 1) and refractory migraine without ischemic cerebral lesions (n = 4). The implanted devices were Occlutech Figulla Flex I/II PFO (n = 99), Occlutech UNI (n = 3), Amplatzer PFO (n = 3) and CeraFlex PFO occluders (n = 1). Procedures were performed under local anesthesia and rotational intracardiac monitoring (Ultra ICE) alone. The devices were correctly implanted in all patients. The mean fluoroscopy time was 15 ± 5 min (range = 10-45 min) and the mean procedural time was 55 ± 20 min (range = 35-90 min). The total occlusion rate at follow-up (mean 50 months, range 3-100) was 98.1%. No recurrent neurological events were observed in the long-term follow-up. CONCLUSIONS: The data collected in this study demonstrate that percutaneous PFO closure is a safe and effective procedure, showing long-term prevention of recurrent cerebrovascular events, significant reduction in migraine symptoms and substantial improvement in quality of life.

Contrast Media Volume Control and Acute Kidney Injury in Acute Coronary Syndrome: Rationale and Design of the REMEDIAL IV Trial.

Background: Although the pathogenesis of acute kidney injury (AKI) in patients with acute coronary syndrome (ACS) undergoing invasive treatment is multifactorial, the role of iodinated contrast media (CM) has been well established. The DyeVert system (Osprey Medical) is designed to reduce the CM volume during invasive coronary procedures while maintaining fluoroscopic image quality. Objective: The aim of the Renal Insufficiency Following Contrast Media Administration Trial IV (REMEDIAL IV) is to test whether the use of the DyeVert system is effective in reducing contrast-associated acute kidney injury (CA-AKI) rate in patients with ACS undergoing urgent invasive procedures. Trial Design: Patients with ACS treated by urgent invasive approach will be enrolled. Participants will be randomly assigned into one of the following groups: (1) DyeVert group and (2) control group. In participants enrolled in the DyeVert group, CM injection will be handled by the DyeVert system. On the contrary, in the control group, CM injection will be performed by a conventional manual or automatic injection syringe. In all cases, iobitridol (a low-osmolar, nonionic CM) will be administered. Participants will receive intravenous 0.9% sodium chloride as soon as moved to the catheterization laboratory. The primary end points are CM volume administration and CA-AKI rate (ie, an increase in serum creatinine concentration of ≥0.3 mg/dL within 48 hours after CM exposure). A sample size of at least 522 randomized participants (261 in each group) is needed to demonstrate an 8.5% difference in the CA-AKI rate between the groups (that is, from 19% in the control group to 10.5% in the DyeVert group), with a 2-sided 95% confidence interval and 80% power (P < .05).

Ischemia in patients with no obstructive coronary artery disease: classification, diagnosis and treatment of coronary microvascular dysfunction.

Patients with coronary microvascular dysfunction represent a widespread population, and despite the good prognosis, many of them, because of the angina symptoms, have a poor quality of life with strong limitations in their daily activities. In 2017, a new classification of microvascular dysfunction as well as a new definition of ischemia in patients with no obstructive coronary artery disease became available. This new definition improves Kemp's initial work, where cardiac X syndrome was initially described. This work summarizes the last updates on the subject with particular attention to the new classification of microvascular dysfunction, with particular attention to microvascular and vasospastic angina definition and diagnostic criteria.

Post-transcriptional silencing and functional characterization of the Drosophila melanogaster homolog of human Surf1.

Mutations in Surf1, a human gene involved in the assembly of cytochrome c oxidase (COX), cause Leigh syndrome, the most common infantile mitochondrial encephalopathy, characterized by a specific COX deficiency. We report the generation and characterization of functional knockdown (KD) lines for Surf1 in Drosophila. KD was produced by post-transcriptional silencing employing a transgene encoding a dsRNA fragment of the Drosophila homolog of human Surf1, activated by the UAS transcriptional activator. Two alternative drivers, Actin5C-GAL4 or elav-GAL4, were used to induce silencing ubiquitously or in the CNS, respectively. Actin5C-GAL4 KD produced 100% egg-to-adult lethality. Most individuals died as larvae, which were sluggish and small. The few larvae reaching the pupal stage died as early imagos. Electron microscopy of larval muscles showed severely altered mitochondria. elav-GAL4-driven KD individuals developed to adulthood, although cephalic sections revealed low COX-specific activity. Behavioral and electrophysiological abnormalities were detected, including reduced photoresponsiveness in KD larvae using either driver, reduced locomotor speed in Actin5C-GAL4 KD larvae, and impaired optomotor response as well as abnormal electroretinograms in elav-GAL4 KD flies. These results indicate important functions for SURF1 specifically related to COX activity and suggest a crucial role of mitochondrial energy pathways in organogenesis and CNS development and function.

Forensic genetic value of a 27 Y-STR loci multiplex (Yfiler(®) Plus kit) in an Italian population sample.

The analysis of Y chromosome short tandem repeat (Y-STR) haplotypes provides important information that can be used for investigative purposes and in population studies. The Yfiler(®) Plus PCR Amplification kit (Yfiler(®) Plus, Thermo Fisher Scientific, Waltham, MA, USA) allows the multiplex amplification of 27 Y-STRs, including 7 rapidly mutating markers (RM Y-STRs). In this study, 203 unrelated males from Italy, which were subdivided into 4 different geographical groups (North, Center, South and Sardinia) were analyzed. Several intra-population diversity indexes were computed and compared to those obtained using only loci either from the minimal haplotype or the 17-plex (Yfiler(®), Thermo Fisher Scientific, Waltham, MA, USA). In addition, inter-population diversity analysis (RST) among the four Italian samples was performed. The same analysis was also used to compare the Italian sub-sets to other European populations where the Yfiler(®) Plus haplotype frequency data were available. The Sardinians were significantly differentiated from the other three Italian groups, thus requiring a specific sub-national Y-STR haplotype database. The Yfiler(®) Plus kit showed a high power of discrimination which is useful for criminal investigations, principally due to the inclusion of RM Y-STRs.

Human identification by lice: A Next Generation Sequencing challenge.

Rapid and progressive advances in molecular biology techniques and the advent of Next Generation Sequencing (NGS) have opened new possibilities for analyses also in the identification of entomological matrixes. Insects and other arthropods are widespread in nature and those found at a crime scene can provide a useful contribution to forensic investigations. Entomological evidence is used by experts to define the postmortem interval (PMI), which is essentially based on morphological recognition of the insect and an estimation of its insect life cycle stage. However, molecular genotyping methods can also provide an important support for forensic entomological investigations when the identification of species or human genetic material is required. This case study concerns a collection of insects found in the house of a woman who died from unknown causes. Initially the insects were identified morphologically as belonging to the Pediculidae family, and then, human DNA was extracted and analyzed from their gastrointestinal tract. The application of the latest generation forensic DNA assays, such as the Quantifiler(®) Trio DNA Quantification Kit and the HID-Ion AmpliSeq™ Identity Panel (Applied Biosystems(®)), individuated the presence of human DNA in the samples and determined the genetic profile.

Quantifiler® Trio Kit and forensic samples management: a matter of degradation.

DNA collected from crime scenes may have experienced different levels of degradation. This is mainly due to sample exposure to different environmental factors. The impact of DNA degradation on short tandem repeat (STR) profiling can lead to partial or null information and in some cases, the identification of the trace may fail. The availability of a system enabling the assessment not only of the quantity of the DNA but also of its quality in terms of degradation would result in shorter time for sample processing, more reliable identifications and cost reduction by predicting the quality of the DNA profiles prior to STR analysis. We report here a study on 181 selected degraded DNA samples extracted from real crime scene evidence. The selected samples were processed by combining the use of a new commercial quantification kit (Quantifiler® Trio) with a new 24 marker multiplex PCR amplification kit (Globalfiler® Kit). Applying different statistical analyses we investigated the reliability of the Degradation Index provided by the Quantifiler® Trio in determining the level of DNA degradation in a forensic sample. This useful information can be used to predict the quality of the profile obtained after STR amplification. The combination of such a quantification kit with different PCR protocols allowed us to define practical guidelines for processing degraded forensic DNA samples with a simplified and comprehensive approach.

Increased longevity and refractoriness to Ca(2+)-dependent neurodegeneration in Surf1 knockout mice.

Leigh syndrome associated with cytochrome c oxidase (COX) deficiency is a mitochondrial disorder usually caused by mutations of SURF1, a gene encoding a putative COX assembly factor. We present here a Surf1-/- recombinant mouse obtained by inserting a loxP sequence in the open reading frame of the gene. The frequency of -/-, +/+ and +/- genotypes in newborn mice followed a mendelian distribution, indicating that the ablation of Surf1 is compatible with postnatal survival. The biochemical and assembly COX defect was present in Surf1(loxP)-/- mice, but milder than in humans. Surprisingly, not only these animals failed to show spontaneous neurodegeneration at any age, but they also displayed markedly prolonged lifespan, and complete protection from Ca(2+)-dependent neurotoxicity induced by kainic acid. Experiments on primary neuronal cultures showed markedly reduced rise of cytosolic and mitochondrial Ca(2+) in Surf1(loxP)-/- neurons, and reduced mortality, compared to controls. The mitochondrial membrane potential was unchanged in KO versus wild-type neurons, suggesting that the effects of the ablation of Surf1 on Ca(2+) homeostasis, and possibly on longevity, may be independent, at least in part, from those on COX assembly and mitochondrial bioenergetics.

Constitutive knockout of Surf1 is associated with high embryonic lethality, mitochondrial disease and cytochrome c oxidase deficiency in mice.

We report here the creation of a constitutive knockout mouse for SURF1, a gene encoding one of the assembly proteins involved in the formation of cytochrome c oxidase (COX). Loss-of-function mutations of SURF1 cause Leigh syndrome associated with an isolated and generalized COX deficiency in humans. The murine phenotype is characterized by the following hallmarks: (1) high post-implantation embryonic lethality, affecting approximately 90% of the Surf1(-/-) individuals; (2) early-onset mortality of post-natal individuals; (3) highly significant deficit in muscle strength and motor performance; (4) profound and isolated defect of COX activity in skeletal muscle and liver, and, to a lesser extent, heart and brain; (5) morphological abnormalities of skeletal muscle, characterized by reduced histochemical reaction to COX and mitochondrial proliferation; (6) no obvious abnormalities in brain morphology, reflecting the virtual absence of overt neurological symptoms. These results indicate a function for murine Surf1 protein (Surf1p) specifically related to COX and recapitulate, at least in part, the human phenotype. This is the first mammalian model for a nuclear disease gene of a human mitochondrial disorder. Our model constitutes a useful tool to investigate the function of Surf1p, help understand the pathogenesis of Surf1p deficiency in vivo, and evaluate the efficacy of treatment.