Late-onset and long-lasting neutropenias in the young: A new entity anticipating immune-dysregulation disorders.

This study identifies a new chronic form of immune neutropenia in the young with or without detectable indirect anti-neutrophil antibodies, characterized by mild/moderate neutropenia low risk of severe infection (14%), tendency to develop autoimmune phenomena over the course of the disease (cumulative incidence of 58.6% after 20 years of disease duration), leukopenia, progressive reduction of absolute lymphocyte count and a T- and B-cell profile similar to autoimmune disorders like Sjogren syndrome, rheumatoid arthritis, and systemic lupus erythematosus (increased HLADR+ and CD3 + TCRγδ cells, reduced T regulatory cells, increased double-negative B and a tendency to reduced B memory cells). In a minority of patients, P/LP variants related to primary immuno-regulatory disorders were found. This new form may fit the group of "Likely acquired neutropenia," a provisional category included in the recent International Guidelines on Diagnosis and Management of Neutropenia of EHA and EUNET INNOCHRON ACTION 18233. The early recognition of this form of neutropenia would help clinicians to delineate better specific monitoring plans, genetic counseling, and potentially targeted therapies.

Role of genetic investigation in the diagnosis of short stature in a cohort of Italian children.

BACKGROUND: Short stature (SS) is defined as height more than 2 standard deviations below the mean for age and sex. Hypothyroidism, celiac disease, growth hormone deficiency, hormonal abnormalities, and genetic conditions are among its causes. A wide range of conditions often due to largely unknown genetic variants can elude conventional diagnostic workup. AIM: We used next-generation sequencing (NGS) to better understand the etiology of SS in a cohort of Italian children. PATIENTS AND METHODS: The study sample was 125 children with SS of unknown origin referred to our Institute between 2015 and 2021. All had undergone complete auxological and hormonal investigations to exclude common causes of SS. Genetic analysis was performed using a NGS panel of 104 genes. Clinical data were reviewed to clarify the pathogenicity of the variants detected. RESULTS: In this cohort, 43 potentially causing variants were identified in 38 children. A syndromic genetic condition was diagnosed in 7: Noonan syndrome in 3, Leri-Weill syndrome in 3, and hypochondroplasia in 1. Moreover, 8 benign variants and other 37 like benign variants were found. In 88 children, 179 variants of uncertain significance (VUS) were identified. No variant was found in 16 children. CONCLUSION: Genetic analysis is a useful tool in the diagnostic workup of patients with SS, in adapting management and treatment, and in identifying syndromes with mild atypical clinical features. The role of VUS should not be underestimated, particularly when multiple VUS with possible mutual worsening effects are present in the same child.

Intervertebral disc and endplate cells response to IL-1ß inflammatory cell priming and identification of molecular targets of tissue degeneration.

Inflammation represents an important factor leading to metabolic imbalance within the intervertebral disc (IVD), conducive to degenerative changes. Therefore, a thorough knowledge of the IVD and endplate (EP) cell behaviour in such pathological environments is essential when designing regenerative therapeutic strategies. The present study aimed at assessing the molecular response of the IVD constitutive nucleus pulposus (NPCs)-, annulus fibrosus (AFCs)- and endplate (EPCs)-derived cells to interleukin (IL)-1ß treatment, through large-scale, high-throughput microarray and protein analysis, identifying the differentially expressed genes and released proteins. Overall, the inflammatory stimulus downregulated stemness genes while upregulating pro-inflammatory, pro-angiogenic and catabolic genes, including matrix metalloproteases, which were not balanced by a concomitant upregulation of their inhibitors. Upregulation of anti-inflammatory and anabolic tumour necrosis factor inducible gene 6 protein (TNFAIP6), of IL-1 receptor antagonist (IL-1Ra) (at gene and protein levels) and of trophic insulin-like growth factor 1 (IGF1) was also observed in all cell types; IGF1 particularly in AFCs. An overall inhibitory effect of tumour necrosis factor alpha (TNFα) signal was observed in all cell types; however, EPCs showed the strongest anti-inflammatory behaviour. AFCs and EPCs shared the ability to limit the activation of the signalling mediated by specific chemokines. AFCs showed a slightly senescent attitude, with a downregulation of genes related to DNA repair or pro-mitosis. Results allowed for the identification of specific molecular targets in IVD and EP cells that respond to an inflammatory environment. Such targets can be either silenced (when pathological targets) or stimulated to counteract the inflammation.

Intervertebral disc and endplate cell characterisation highlights annulus fibrosus cells as the most promising for tissue-specific disc degeneration therapy.

Degenerative processes of the intervertebral disc (IVD) and cartilaginous endplate lead to chronic spine pathologies. Several studies speculated on the intrinsic regenerative capacity of degenerated IVD related to the presence of local mesenchymal progenitors. However, a complete characterisation of the resident IVD cell populations, particularly that isolated from the endplate, is lacking. The purpose of the present study was to characterise the gene expression profiles of human nucleus pulposus (NPCs), annulus fibrosus (AFCs) and endplate (EPCs) cells, setting the basis for future studies aimed at identifying the most promising cells for regenerative purposes. Cells isolated from NP, AF and EP were analysed after in vitro expansion for their stemness ability, immunophenotype and gene profiles by large-scale microarray analysis. The three cell populations shared a similar clonogenic, adipogenic and osteogenic potential, as well as an immunophenotype with a pattern resembling that of mesenchymal stem cells. NPCs maintained the greatest chondrogenic potential and shared with EPCs the loss of proliferation capability during expansion. The largest number of selectively highly expressed stemness, chondrogenic/tissue-specific and surface genes was found in AFCs, thus representing the most promising source of tissue-specific expanded cells for the treatment of IVD degeneration.

Magnetic resonance arthrography accuracy in the detection of labral tears in young patients with chronic unstable shoulder: correlation with arthroscopy.

The aim of this study is to determine the diagnostic performance of Magnetic Resonance Arthrography (MRA) in evaluating lesions of the glenoid labrum, in young active patients with chronic unstable shoulder, compared to shoulder arthroscopy. We retrospectively considered 65 MRA examinations, performed between December 2011 and January 2018. Among them, thirty-five patients (31 men, 4 women; mean age, 27.3 years; range, 16-53 years; 4 patients with a previous arthroscopy of the same shoulder) underwent shoulder arthroscopy after MRA. Arthroscopic reports were collected and analyzed for the correlation with MRA results.

Prevalence of HIV Viral Load Suppression Among Psychiatric Inpatients with Comorbid Substance Use Disorders.

A consistently suppressed viral load enables HIV (+) patients to live longer, healthier lives and reduces the probability of transmitting the virus. Since the prevalence of HIV is four times higher among those with psychiatric disorders than in the general population, it is likely that this group would also have greater difficulty remaining in care and achieving viral suppression. A secondary data analysis utilizing screening data from the Preventing AIDS Through Health (PATH) for Triples (PFT) Study were examined to assess HIV load suppression among 254 psychiatric inpatients with comorbid substance use disorders in Philadelphia. Viral load results from the past 12 months were obtained from medical records for 63 inpatients identified as HIV (+). The sample was predominately African American (76%), male (56%), and the average age was 43 years. Psychiatric disorders included depression (64%), schizophrenia (21%), and bipolar disorder (13%) with patients reporting use of alcohol (73%), cocaine (64%), cannabis (29%) and opioids (16%) prior to admission. Among this high risk sample of HIV (+) patients, about one-half (52%) achieved viral suppression, with recent opioid users six times more likely to have a detectable viral load than non-opioid users (OR 6.0; CI 1.1-31.7, p = .035). The 52% viral load suppression rate among psychiatric inpatient was higher than expected, given that the CDC's national suppression rate among those diagnosed with HIV in the general population is 58%. However, individuals with mental illness and substance use disorders require constant surveillance, monitoring, and supportive services to achieve viral suppression. Many of those who were virally suppressed were engaged in Philadelphia's extensive treatment network, whereas those who were detectable and enrolled in the PFT intervention were often homeless with unstable psychiatric symptoms and current substance use disorders, particularly opioid abuse.

Generation of induced Pluripotent Stem Cells as disease modelling of NLSDM.

Neutral Lipid Storage Disease with Myopathy (NLSDM) is a rare defect of triacylglycerol metabolism, characterized by the abnormal storage of neutral lipid in organelles known as lipid droplets (LDs). The main clinical features are progressive myopathy and cardiomyopathy. The onset of NLSDM is caused by autosomal recessive mutations in the PNPLA2 gene, which encodes adipose triglyceride lipase (ATGL). Despite its name, this enzyme is present in a wide variety of cell types and catalyzes the first step in triacylglycerol lipolysis and the release of fatty acids. Here, we report the derivation of NLSDM-induced pluripotent stem cells (NLSDM-iPSCs) from fibroblasts of two patients carrying different PNPLA2 mutations. The first patient was homozygous for the c.541delAC, while the second was homozygous for the c.662G>C mutation in the PNPLA2 gene. We verified that the two types of NLSDM-iPSCs possessed properties of embryonic-like stem cells and could differentiate into the three germ layers in vitro. Immunofluorescence analysis revealed that iPSCs had an abnormal accumulation of triglycerides in LDs, the hallmark of NLSDM. Furthermore, NLSDM-iPSCs were deficient in long chain fatty acid lipolysis, when subjected to a pulse chase experiment with oleic acid. Collectively, these results demonstrate that NLSDM-iPSCs are a promising in vitro model to investigate disease mechanisms and screen drug compounds for NLSDM, a rare disease with few therapeutic options.

Mutation frequencies of GNAQ, GNA11, BAP1, SF3B1, EIF1AX and TERT in uveal melanoma: detection of an activating mutation in the TERT gene promoter in a single case of uveal melanoma.

BACKGROUND: Uveal melanoma is the most frequent primary tumour of the eye. It is molecularly clearly distinct from cutaneous melanoma and shows a different pattern of driver mutations. The influence of sunlight ultraviolet (UV) exposure on the aetiology of uveal melanoma is a matter of debate. The recent identification of driver mutations in the promoter of the telomerase reverse transcriptase (TERT) gene with UV-induced cytidine-to-thymidine transitions in cutaneous melanoma prompted us to investigate whether these mutations also occur in uveal melanoma. METHODS: We analysed 50 cases of uveal melanoma obtained from enucleation surgery for mutations in the genes GNAQ, GNA11, BAP1, SF3B1, EIFAX1 and TERT, measured gene expression using microarrays and analysed gene copy numbers by SNP arrays. RESULTS: We detected a TERT mutation in only one case of a 57-year-old white male patient with clinical and histopathological features typical for uveal melanoma. The tumour showed mutations in GNA11 and EIF1AX that are typical for uveal melanoma and absent from cutaneous melanoma. No mutations were detected in GNAQ, BAP1 and SF3B1 that are frequently mutated in uveal melanoma. Both copies of chromosome 3 were retained. Several tumours among which the one carrying the TERT promoter mutation showed elevated TERT expression. Consistent with previous reports, GNAQ is inversely associated with chromosome 3 monosomy and metastasis. BAP1 mutations are significantly associated with chromosome 3 monosomy but not with relapse. CONCLUSION: These data indicate that TERT mutations are rare in uveal melanoma. No conclusion can be drawn on their potential influence on tumour progression.

Reclaimed wastewater reuse in irrigation: Role of biofilms in the fate of antibiotics and spread of antimicrobial resistance.

Reclaimed wastewater associated biofilms are made up from diverse class of microbial communities that are continuously exposed to antibiotic residues. The presence of antibiotic resistance bacteria (ARB) and their associated antibiotic resistance genes (ARGs) ensures also a continuous selection pressure on biofilms that could be seen as hotspots for antibiotic resistance dissemination but can also play a role in antibiotic degradation. In this study, the antibiotic degradation and the abundance of four ARGs (qnrS, sul1, blaTEM, ermB), and two mobile genetic elements (MGEs) including IS613 and intl1, were followed in reclaimed wastewater and biofilm samples collected at the beginning and after 2 weeks of six antibiotics exposure (10 µg L-1). Antibiotics were partially degraded and remained above lowest minimum inhibitory concentration (MIC) for environmental samples described in the literature. The most abundant genes detected both in biofilms and reclaimed wastewater were sul1, ermB, and intl1. The relative abundance of these genes in biofilms increased during the 2 weeks of exposure but the highest values were found in control samples (without antibiotics pressure), suggesting that bacterial community composition and diversity are the driven forces for resistance selection and propagation in biofilms, rather than exposure to antibiotics. Planktonic and biofilm bacterial communities were characterized. Planktonic cells are classically defined "as free flowing bacteria in suspension" as opposed to the sessile state (the so-called biofilm): "a structured community of bacterial cells enclosed in a self-produced polymeric matrix and adherent to an inert or living. surface" as stated by Costerton et al. (1999). The abundance of some genera known to harbor ARG such as Streptococcus, Exiguobacterium, Acholeplasma, Methylophylaceae and Porphyromonadaceae increased in reclaimed wastewater containing antibiotics. The presence of biofilm lowered the level of these genera in wastewater but, at the opposite, could also serve as a reservoir of these bacteria to re-colonize low-diversity wastewater. It seems that maintaining a high diversity is important to limit the dissemination of antimicrobial resistance among planktonic bacteria. Antibiotics had no influence on the biofilm development monitored with optical coherence tomography (OCT). Further research is needed in order to clarify the role of inter-species communication in biofilm on antibiotic degradation and resistance development and spreading.

Scoliosis with cognitive impairment in a girl with 8q11.21q11.23 microdeletion and SNTG1 disruption.

Idiopathic scoliosis (IS) is an abnormality of the vertebral column with a spine curvature of at least 10 degrees. It is the most common spinal deformity in children with a prevalence of 2%-3%, and its aetiology is unknown. Genetic factors are known to play a role and a number of linkage analyses showed associations of various loci. Here we describe a new case of a de novo interstitial deletion 8q11.21q11.2 disrupting SNTG1 gene, identified by array-CGH in a girl with cognitive impairment and a scoliosis that 'appears' like to IS. SNTG1 encodes γ-1 Syntrophin protein that is part of the dystrophin associated protein complex and interacts directly with the C-terminal of dystrophin. Its expression is restricted to neurons and particularly in those areas of the brain that have been suggested to affect postural control. The involvement of SNTG1 gene in IS was already been reported in a family with a breakpoint between exons 10 and 11. Mutational analysis of SNTG1 exons in 152 sporadic IS patients had revealed changes in three patients. In conclusion, our data add a further line of evidence suggesting SNTG1 could represent an interesting candidate for its involvement in scoliosis.

Single-nucleotide polymorphisms in 3'-untranslated region inducible costimulator gene and the important roles of miRNA in alopecia areata.

Background: Alopecia areata (AA) spares the stem cell compartment and attacks only the base of the hair follicle, which is surrounded by infiltrating lymphocytes. AA is associated with polymorphisms in immune-related genes and with decreased function of CD4+CD25+ T regulatory (Treg) cells. Treg function is modulated by the costimulatory molecules, like inducible costimulator (ICOS) that are crucial in orienting T cell differentiation and function so that they strongly impact on the immunologic decision between tolerance or autoimmunity development. Objective: The aim of our study was to investigate the possible association of AA with single-nucleotide polymorphisms (SNP) present in the ICOS 3'-untranslated region (3'UTR) region and to elucidate how SNPs modulate ICOS gene expression by affecting miRNA binding sites. Methods: This is a case-control study performed in 184 patients with AA and 200 controls. ICOS gene and miRNA expression were analyzed by real-time polymerase chain reaction. Results: The genotype carrying the rs4404254(C) [p = 0.012, OR (95% CI): 0.5 (0.3-0.8)] and rs4675379(C) [p = 0.015, OR (95% CI): 0.3 (0.1-0.8)] 3' UTR alleles was more frequently observed in AA patients than in controls and correlated with a reduced ICOS expression. miR-1276 significantly suppressed ICOS expression by binding to the 3'UTR of ICOS mRNA. Also, we observed that, miR-101 and miR-27b are upregulated, while miR-103 and miR-2355-3p are downregulated in peripheral blood mononuclear cells of AA patients compared to controls. Conclusion: Our data show that rs4404254 and rs4675379 SNPs of ICOS gene are associated with AA and also reveal that the presence of rs4404254 polymorphism correlates with ICOS post-transcriptional repression by microRNA binding.

17q23.3 de novo microdeletion involving only TANC2 gene: A new case.

Neurodevelopmental disorders (NDDs) show a wide range of overlapping clinical features. Intellectual disability (ID), developmental delay (DD), autism spectrum disorder (ASD), attention-deficit hyperactivity disorder (ADHD), language and communication disorders with or without motor abnormalities and/or epilepsy have been reported associated to single or multiple genes but in many cases the genetic basis remains unknown. The increasingly use of array-CGH has significantly improved the yield of diagnosing genomic disorders and led to the identification of several novel microdeletion and microduplication syndromes. TANC2 encodes a synaptic scaffold protein interacting with multiple neuropsychiatric disorder-related postsynaptic density (PSD) proteins in dendrites. Here, we describe a new case of TANC2 gene disruption in a 17q23.3 de novo microdeletion identified by array-CGH. The patient presented craniofacial dysmorphic features, hypotonia, and severe cognitive and motor impairment. In conclusion, our data add a further line of evidence supporting the role of TANC2 in NDDs and will help further researches to elucidate the regulatory mechanism of synaptic function and plasticity related to TANC2 haploinsufficiency.

A randomized study to assess two different techniques of aspiration while performing transabdominal chorionic villus sampling.

OBJECTIVE: The technique used to perform transabdominal chorionic villus sampling (CVS) is not standardized, but aspiration of villi is generally obtained by discontinuous vacuum created in a syringe, manually or by a hand-grip device. We evaluated the feasibility of a new method of performing CVS which employs a 4-mL Vacutainer connected to the needle, producing a continuous negative pressure. METHODS: Two hundred pregnant women, whose gestational age ranged from 10 + 2 to 16 + 2 (mean, 12 + 1) weeks, entered the randomized study, which was powered to detect with 90% probability the absence of any difference in the size of chorionic samples obtained by using a 20-mL syringe with the vacuum obtained by a hand-grip device (Group 1) or by a vacutainer (Group 2). Four operators with different levels of experience performed all the procedures, which were done transabdominally using a freehand technique with a 20-gauge needle under ultrasound guidance. RESULTS: Maternal age, body mass index, gestational age and the way the needle was inserted within the chorion were similar in the two groups. The median amount of villi sampled was 20 mg, with no differences between the two groups. The rate of fetal loss was 1.7%. All losses occurred in women of Group 1 who had only one needle insertion. A second needle insertion was required more frequently while using the vacutainer. CONCLUSION: This new technique for performing transabdominal CVS uses a readily available device and is as effective as traditional sampling systems to aspirate villi. It has the advantage of being a one-operator procedure.

Molecular and clinical features associated with CFTR gene rearrangements in Italian population: identification of a new duplication and recurrent deletions.

Cystic fibrosis (CF) is mainly caused by small deletions or missense mutations in the CFTR gene. The CF mutation database lists more than 35 large rearrangements that may escape detection using polymerase chain reaction-base techniques. The Innogenetics assay, the denaturing high-performance liquid chromatography and sequencing screening showed a mutation detection rate of 92.6% in our population. We report here the results of multiplex ligation-dependent probe amplification (MLPA) screening for CFTR gene rearrangements, performed on the unidentified alleles of our CF patients. Our sample population consists of 692 non-related Italian CF patients (for a total of 1384 alleles), followed at CF Centres in the Lombardia Region. MLPA analysis was performed in 49 patients who still had one or two unidentified alleles (for a total of 52 unidentified alleles) after extensive analysis of CFTR gene. All patients who were studied had the classical form of CF. We characterized nine different deletions and a new duplication. The deletion of exons 22-23 (7/82) was the most frequent in our cohort. The search for deletion/duplications of the CFTR gene has made it possible to reach a 94.1% detection rate, with an improvement (1.6%) of the carrier detection rate in the Italian population.

Terminal erythroid differentiation in the K-562 cell line by 1-beta-D-arabinofuranosylcytosine: accompaniment by c-myc messenger RNA decrease.

Two erythroid markers, acetylcholinesterase and hemoglobin, can be reversibly induced in the K-562 cell line after sodium butyrate treatment. In the present paper we show that 1-beta-D-arabinofuranosylcytosine (ara-C), induces the coordinate, irreversible expression of these two erythroid markers. This induction occurs at an ara-C concentration (0.05 mM) that results in K-562 cytostasis and is accompanied by deep morphological changes of cells. The differentiated phenotype is independent of the K-562 cell clone used [K-562, K-562 (S), K-562 (S)P] and is associated with the loss of cell renewal capacity. Continuous presence of the inducer is not necessary to achieve terminal differentiation. In contrast to what is seen for other inducers (sodium butyrate and hemin), one of the early effects of ara-C treatment is the marked decrease of c-myc mRNA expression after the first 4 hours of induction, whereas N-ras and histone 4 expression remain constant during the first 48 h. Our results suggest that ara-C treatment can irreversibly activate the erythroid differentiative program of K-562 cells.

Estradiol inhibits growth of hormone-nonresponsive PC3 human prostate cancer cells.

Significant inhibition of proliferative activity in PC3 human prostate cancer cells by estradiol is reported, accompanied by experimental evidence for a specific estrogen receptor (ER). Radioligand-binding assays revealed the presence of high affinity sites of estrogen binding in the nuclear compartment of PC3 cells. In addition, using a reverse transcriptase-polymerase chain reaction system, we obtained evidence of either normal or a variant ER mRNA; the latter, which lacks the entire exon 4, is coexpressed with normal ER mRNA and has been recently characterized in our laboratories. The likelihood that the inhibitory effect exerted by estradiol could be mediated by an increase of transforming growth factor beta (TGF beta) production was also investigated. Use of monoclonal antibodies against TGF beta 1 produced a 3-fold increase of growth rate in PC3 cells; this clearly speaks for high levels of endogenous TGF beta 1. This effect was almost completely abolished after addition of 100 nM estradiol. However, we failed to demonstrate any increase of TGF beta 1 mRNA after estradiol administration using Northern blot analysis. Further studies are needed to ascertain whether the estradiol-induced growth inhibition of PC3 cells is either mediated by other TGF beta species or exerted via alternative mechanism(s).

Expression and alternative splicing of fibronectin mRNA in human diploid endothelial cells during aging in vitro.

Different mRNAs for fibronectin arise from the variable processing of a single primary transcript. We used ribonuclease protection assay to investigate the changes occurring in fibronectin expression and the alternative splicing of mRNA precursor during aging in vitro of human diploid endothelial cells. Senescent endothelial cells release more protein and contain 4-5-fold more fibronectin mRNA than young cells. The pattern of alternative splicing of fibronectin mRNA, with the EDA and the CS1 segments largely included (35% and 77%, respectively) and the EDB segment undetectable, correlates well with previous studies at the protein level both in vitro and in vivo. No changes in the splicing pattern of fibronectin mRNA precursor were detected during endothelial cellular senescence. The increased expression of fibronectin in senescent cells may be a result of the activity of interleukin-1 alpha, which is overexpressed in senescent endothelial cells. It could be also important in vivo during aging and in atherosclerotic lesions.

Maternally inherited cardiomyopathy: clinical and molecular characterization of a large kindred harboring the A4300G point mutation in mitochondrial deoxyribonucleic acid.

OBJECTIVES: The purpose of this study was to describe the clinical and molecular features of a large family with maternally inherited cardiomyopathy (MICM). BACKGROUND: Recently, several mitochondrial deoxyribonucleic acid (mtDNA) point mutations have been associated with MICM. However, the distinctive clinical and morphologic features of MICM are not fully appreciated. This is partially due to the small size of the reported pedigrees, often lacking detailed clinical and laboratory information. METHODS: Clinical and genetic analysis of the family was carried out. RESULTS: Echocardiography showed mostly symmetrical hypertrophic cardiomyopathy in 10 family members. The illness had an unfavorable course. Progressive heart failure occurred in three subjects, who eventually died; one individual underwent heart transplantation. Electrocardiographic or echocardiographic signs of cardiac hypertrophy in the absence of significant clinical complaints were observed in five subjects. Neurologic examination was normal. The mutation was detected in blood from all available subjects. Abundance of mutated molecules ranged between 13% and 100% of total mtDNA genomes. The severity of the disease could not be foreseen by the proportion of mutation in blood. CONCLUSIONS: This report contributes a better description of the clinical aspects of MICM and provides important clues to distinguish it from hypertrophic cardiomyopathy. We suggest that mtDNA mutations, particularly in the transfer ribonucleic acid for isoleucin, should be systematically searched in patients with MICM. The identification of an underlying maternally inherited mitochondrial DNA defect in familial cases of cardiomyopathy may considerably influence the management and genetic counseling of affected patients.

Clinical features of hypertrophic cardiomyopathy caused by mutation of a "hot spot" in the alpha-tropomyosin gene.

OBJECTIVES: We studied the clinical and genetic features of familial hypertrophic cardiomyopathy (FHC) caused by an Asp175Asn mutation in the alpha-tropomyosin gene in affected subjects from three unrelated families. BACKGROUND: Correlation of genotype and phenotype has provided important information in FHC caused by beta-cardiac myosin and cardiac troponin T mutations. Comparable analyses of hypertrophic cardiomyopathy caused by alpha-tropomyosin mutations have been hampered by the rarity of these genetic defects. METHODS: The haplotypes of three kindreds with FHC due to an alpha-tropomyosin gene mutation, Asp175Asn, were analyzed. The cardiac histopathologic findings of this mutation are reported. Distribution of left ventricular hypertrophy in affected members was assessed by two-dimensional echocardiography, and patient survival rates were compared. RESULTS: Genetic studies defined unique haplotypes in the three families, demonstrating that independent mutations caused the disease in each. The Asp175Asn mutation caused cardiac histopathologic findings of myocyte hypertrophy, disarray and replacement fibrosis. The severity and distribution of left ventricular hypertrophy varied considerably in affected members from the three families (mean maximal wall thickness +/- SD: 24 +/- 4.5 mm in anterior septum of Family DT; 15 +/- 2.7 mm in anterior septum and free wall of Family DB; 18 +/- 2.1 mm in posterior septum of Family MI), but survival was comparable and favorable. CONCLUSIONS: Nucleotide residue 579 in the alpha-tropomyosin gene may have increased susceptibility to mutation. On cardiac histopathologic study, defects in this sarcomere thin filament component are indistinguishable from other genetic etiologies of hypertrophic cardiomyopathy. The Asp175Asn mutation can elicit different morphologic responses, suggesting that the hypertrophic phenotype is modulated not by genetic etiologic factors alone. In contrast, prognosis reflected genotype; near normal life expectancy is found in hypertrophic cardiomyopathy caused by the alpha-tropomyosin mutation Asp175Asn.