The postnatal maturation of regions of the epididymis and intragonadal segment of the deferens duct was studied in the rat by light- and transmission electron microscopy. Maturation of the genital duct starts in the distal cauda epididymidis and ductus deferens after one week of life, and one week later, in the more cranial segments of the epididymis. Epithelial principal cells and peritubular contractile cells are structurally mature 35 days after birth. The synchronous changes of these cells indicate that the same factors control their postnatal maturation. The epithelial principal cells obtain an endocytotic apparatus and long stereocilia, whereas peritubular cells acquire contractile features. These changes are associated with a progressive increase in the immunoreaction for smooth muscle actin in both cell types. Smooth muscle myosin is detected in the apical region of the epithelial cells and the peritubular cell cytoplasm by day one of postnatal development. The differentiation of contractile cells in the wall is accompanied by progressive organization of the pericellular matrix into a continuous basement membrane. Although fibronectin is visible at birth, it is gradually removed from the tubule wall.

A quantitative analysis of Leydig cells was performed in 23 testicular biopsies of men with left varicocele and sperm count ranging from zero to 95,000 sperm/mm3. The oligozoospermic patients had more Leydig cells and higher FSH and LH serum levels than the patient group with more than 10,000 sperm/mm3. The Leydig cell density appeared tightly correlated (p less than 0.01) with the serum level of LH. In oligozoospermic subjects, an altered Leydig cell function could trigger an increased LH secretion; this seems likely to be responsible for the stimulation of interstitial cells resulting in an exaggerated recruitment of mature Leydig cells from their precursors. The comparative analysis of left and right testes failed to show differences in Leydig cell density and spermatogenesis in normozoospermic and oligozoospermic patients. This suggests that the two testes are equally involved by a possible, although unknown, detrimental effect of left side varicocele.

The postnatal maturation of the epithelium and tubule wall of efferent tubules in the rat was investigated by light and transmission electron microscopy, from birth to 50 days of age, when sperms were released from the seminiferous tubules and appeared in the genital duct. At the end of the first week of life, an endocytotic apparatus is differentiated in the epithelial cells. During the third week of life, efferent tubules developed specializations for the transport of sperms and fluids, namely the appearance of ciliated elements interspersed among the principal cells of the epithelium, and differentiation of myoid elements in the tubule wall. The appearance of specializations related to endocytosis and fluid transport across the epithelium preceded the canalization of the seminiferous cords which, in fact, is reported to appear at the end of the second week of life in the rat, along with the initial secretion of testicular fluid. This suggested that the maturation of efferent tubules is not triggered by the passage of testicular fluid, as surmised for the postnatal differentiation of caput epididymis. The postnatal maturation of efferent tubules was almost complete 35 days after birth. The appearance of sperms in the genital duct of 50-day-old animals was not associated with any remarkable structural change.

Mutations in the MYBPC3 gene, which encodes myosin C–binding protein C (cMyBP–C) are among the main causes of hypertrophic cardiomyopathy (HCM). Truncating mutations are recognized as causative in many HCM patients and recently, even missense mutations (e.g E258K mutation) appear to be clinically related to the disease. E258K is one of the most common MYBPC3 mutations, with a prevalence of 15% in Italians. We report a family case, with father and son affected by HCM in which where this mutation was identified thanks to the NGS. HCM in the father was diagnosed at the age of 70 after several episodes of atrial fibrillation and after a myocardial infarction. The son, a sportsman, had a very early and severe presentation of HCM in the absence of manifest clinical signs. The same E258K mutation was also found in the proband son, in the absence of clinical signs of HCM. Given the diversity of the carrier phenotypes, the molecular analysis of the proband was extended beyond rare variants and we found a common substitution in the DES gene, (encoding desmin) which, acting as an unfavourable modifier, could partly explain the different clinical presentation of HCM. Probably also the intense physical activity carried out by the proband contributed to the phenotype severity. The father, asymptomatic for a much longer period and with a lower hypertrophy grade compared to the proband, may have benefited from a less intense physical activity and from the absence of the DES polymorphism. To date, the role of physical exercise is widely debated: on the one hand, a regular intense physical training could worsen hypertrophy, fibrosis and trigger arrhythmias, on the other hand however, a sedentary lifestyle predisposes to obesity and other cardiovascular risk factors which induce diseases with a worse prognosis than HCM itself. Nowadays 70% of patients with HCM are overweight, and more than 50% are below the minimum recommended exercise threshold. In addition, there is growing evidence that competitive sports are safe and could have beneficial effects in asymptomatic low–risk HCM patients. This case study suggests that the decision–making process must include both genotypic and phenotypic characterization of patients, as well as the evaluation of the causative mutation pathogenicity and of co–existing genetic modifiers.

A 65–year–old man came to our hospital for a subacute stroke of the left parietotemporal area. An aorto–coronary bypass for stable coronary artery disease and aortobisiliac bypass for infrarenal aortic aneurysm (with post–operative courses complicated by multiple atrial fibrillation paroxisms which were pharmacologically cardioverted) was reported. No undergoing anticoagulant therapy for CHADSVASc=1 was reported. Hypothesizing a cardioembolic origin of the stroke, echocardiographic analysis was performed which showed increased ventricular thickness and mass, inhomogeneous texture, reduced systolic function and strain with apical sparing, II degree diastolic dysfunction and severe left atrial dilatation. The strong suspicion of amyloidosis, raised by the echocardiographic findings, was confirmed by bone scintigraphy. The absence of free immunoglobulin chains in blood and urine and a normal protein electrophoretic pattern, would have instead excluded the diagnosis of AL amyloidosis. Thus we performed genetic testing to characterize the type of ATTR (transthyretin). An homozygous Val142Ile mutation in exon 4 of the TTR gene was found. This mutation, typically found in patients of African ancestry, is extremely rare in the Caucasian population. In fact, only 5 cases of patients with this mutation and with phenotypic manifestations very similar to the African ancestral ones have been so far reported, thus indicating that this mutation is not restricted to African ancestry but may be an underestimated Caucasian variant. The large GnomAD database estimates that this homozygous mutation is present in only 0.72% of the general population, while the remaining part of the carriers are heterozygous. Val142Ile leads to increased formation of amyloid fibrils and to the formation of a particularly unstable TTR tetramer. This variant is associated with a worse quality of life, a higher incidence of AF and a lower survival than the wild type TTR. In light of the worse clinical outcomes associated to this variant it is therefore essential to maintain a high level of clinical suspicion in order to perform an early diagnosis from a clinical and molecular point of view in order to be able to direct the patient as soon as possible to the current available therapies that can modify the course of the pathology and avoid premature fatal events.

A 62–year–old man diagnosed with non–obstructive hypertrophic cardiomyopathy and dual–chamber pacemaker wearer since the age of 40, for third–degree atrioventricular block, came to our attention for atrial fibrillation (AF) episodes (one complicated by cardiogenic shock and multiorgan failure) and flutter with high ventricular response. For a progressive worsening of the systolic function, and the onset of multiple episodes of sustained ventricular tachycardia, an upgrade to the defibrillator was performed, which, in the following months, intervened appropriately for recurrences of ventricular arrhythmias. The patient was admitted to our ward for exacerbation of heart failure. The echocardiography showed moderate concentric hypertrophy with mild ventricular dilatation and ejection fraction 33%, inferior and inferoseptal wall, and apex akinesia with thrombotic apposition. Due to a sudden deterioration of the clinical conditions, the patient died. After genetic counseling the patient‘s family agreed to genetic testing in the proband. This highlighted the presence of a missense mutation, i.e. the substitution of the cysteine ​​residue with a serine, in the codon 905 of the MYH7 gene, encoding the cardiac isoform of myosin heavy chain. The mutation is probably pathogenetic as it falls in the region where most of the missense variants are clustered and statistically associated with the HCM phenotype. Only in one previous case of HCM was detected a mutation of the same codon, Cys905Phe. Several studies have reported that AF tends to be more prevalent in patients carrying MYH7 mutations and is associated with a substantial risk of heart failure–related mortality, stroke, and severe functional disability. Knowledge of the entire spectrum of MYH7 mutations, especially those related to a high arrhythmic burden or SCD, combined with an accurate clinical and molecular characterization of the patient, can improve the genotype–phenotype correlation by clarifying the mechanism of HCM and allowing a better clinical and therapeutic decision–making of patients.

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