The pituitary-testicular axis in Klinefelter's syndrome and in oligo-azoospermic patients with and without deletions of the Y chromosome long arm

OBJECTIVE: The most frequent known genetic causes of severe oligospermia (< 5 million sperm/ml) or azoospermia in men are Klinefelter's syndrome (KS), and deletions in the Y chromosome long arm (Yq). We aimed to compare the function of the pituitary-testicular axis in patients with severe oligospermia or azoospermia, idiopathic or associated with Y chromosome deletions or Klinefelter's syndrome (KS) and in control subjects. PATIENTS: We studied 47 men with idiopathic oligo-azoospermia, 42 with Yq deletions (27 AZFc, 13 AZFb and two AZFa) and oligo-azoospermia, 14 with KS and 39 control subjects (total 143). MEASUREMENTS: We analysed levels of FSH, inhibin-B, LH, free testosterone and oestradiol in all subjects, and we calculated indexes based on those hormones. RESULTS: Inhibin-B levels were indistinguishable between patients with idiopathic and Y deletion-associated oligo-azoospermia, lowest in the Klinefelter's patients and highest in controls. FSH levels followed the reverse pattern: indistinguishable between patients with idiopathic and deletion-associated oligo-azoospermia, highest in Klinefelter's patients and lowest in controls. Oestradiol, free testosterone and the derived indeces were not different in subjects with Yq deletions compared to those with idiopathic oligo-azoospermia. Among the Yq-deleted patients, no measured or derived parameter differed between the subjects with AZFc deletion and those with AZFb deletion. When non-KS oligo-azoospermic patients were classified according to histology [Sertoli cell-only (SCO), n = 18 or non-Sertoli cell only (non-SCO), n= 18] and compared to KS patients, the hormonal pattern did not differ between SCO and non-SCO subjects, but levels in KS patients were significantly different for FSH, inhibin-B and the FSH/inhibin-B ratio. KS patients not only had lower inhibin-B than SCO and non-SCO oligo-azoospermic men, but also higher FSH levels for any given inhibin-B concentration. CONCLUSION: Our data show that Y-deleted patients do not have a lesser impairment of Sertoli cell function than patients with idiopathic oligo-azoospermia, and support the concept that the main determinant of inhibin-B production is the germ cell mass. Also, our results suggest that one or more other factors, apart from inhibin-B, may contribute to increased pituitary secretion of FSH in KS patients.     

Y chromosome microdeletions and alterations of spermatogenesis

Three different spermatogenesis loci have been mapped on the Y chromosome and named "azoospermia factors" (AZFa, b, and c). Deletions in these regions remove one or more of the candidate genes (DAZ, RBMY, USP9Y, and DBY) and cause severe testiculopathy leading to male infertility. We have reviewed the literature and the most recent advances in Y chromosome mapping, focusing our attention on the correlation between Y chromosome microdeletions and alterations of spermatogenesis. More than 4,800 infertile patients were screened for Y microdeletions and published. Such deletions determine azoospermia more frequently than severe oligozoospermia and involve especially the AZFc region including the DAZ gene family. Overall, the prevalence of Y chromosome microdeletions is 4% in oligozoospermic patients, 14% in idiopathic severely oligozoospermic men, 11% in azoospermic men, and 18% in idiopathic azoospermic subjects. Patient selection criteria appear to substantially influence the prevalence of microdeletions. No clear correlation exists between the size and localization of the deletions and the testicular phenotype. However, it is clear that larger deletions are associated with the most severe testicular damage. Patients with Y chromosome deletions frequently have sperm either in the ejaculate or within the testis and are therefore suitable candidates for assisted reproduction techniques. This possibility raises a number of medical and ethical concerns, since the use of spermatozoa carrying Y chromosome deletions may produce pregnancies, but in such cases the genetic anomaly will invariably be passed on to male offspring.     

Molecular and clinical characterization of Y chromosome microdeletions in infertile men: a 10-year experience in Italy

CONTEXT: An explosive growth in Y chromosome long arm (Yq) microdeletion testing demand for male infertility occurred in the past few years. However, despite the progresses in the biology of this chromosome, a number of molecular and clinical concerns are not supported by definitive data. OBJECTIVE: The objective was to provide information on the type and prevalence of microdeletions in infertile males, indication for testing, genotype-phenotype correlation, sperm aneuploidies, and genetic counseling. DESIGN AND SETTING: We performed a prospective study from January 1996 to December 2005 in an academic clinic. PATIENTS: We studied 3073 consecutive infertile men, of which 625 were affected by nonobstructive azoospermia and 1372 were affected by severe oligozoospermia. Ninety-nine patients with microdeletions are described here. MAIN OUTCOME MEASURES: Yq microdeletions, seminal analysis, reproductive hormones, testicular cytology/histology, and sperm sex chromosomes aneuploidies were used as outcome measures. RESULTS: The prevalence of microdeletions was 3.2% in unselected infertile men, 8.3% in men with nonobstructive azoospermia, and 5.5% in men with severe oligozoospermia. Only 2 of 99 deletions were found in men with more than 2 million sperm/ml. No clinical data are useful to identify a priori patients with higher risk of Yq microdeletions. Most deletions are of the AZFc-b2/b4 subtype and are associated with variable spermatogenic phenotype, with sperm present in 72% of the cases. Complete AZFa and AZFb (P5/Proximal P1) deletions are associated with Sertoli cell-only syndrome and alterations in spermatocyte maturation, respectively, whereas partial deletions in these regions are associated with milder phenotype and frequent presence of sperm. Men with AZFc-b2/b4 deletions produce a higher percentage of sperm with nullisomy for the sex chromosomes and XY-disomy. CONCLUSIONS: This extensive clinical research expands the knowledge on genotype-phenotype relationships and confirms that the identification of Yq microdeletions has significant diagnostic and prognostic value, adding useful information for genetic counseling in these patients.     

Y chromosome microdeletions in cryptorchidism and idiopathic infertility.

To clarify whether cryptorchidism might be the expression of an intrinsic congenital testicular abnormality, we investigated the frequency of Y chromosome long arm (Yq) microdeletions in unilateral excryptorchid subjects manifesting an important bilateral testiculopathy. Microdeletion analysis of Yq was performed by polymerase chain reaction in the following subjects: 40 unilateral excryptorchid patients with azoospermia or severe oligozoospermia due to a bilateral severe testiculopathy (Sertoli cell-only syndrome or severe hypospermatogenesis); 20 unilateral excryptorchid men with moderate oligozoospermia and a normal testicular cytological picture in the contralateral testis; 110 patients affected by idiopathic severe primary testiculopathies; 20 patients affected by idiopathic moderate testiculopathy; and, as controls, 50 patients affected by known causes of testiculopathy and 100 fertile men. Eleven of 40 (27.5%) unilateral excryptorchid patients affected by bilateral testiculopathy and 28 of 110 (25.4%) patients affected by idiopathic severe primary testiculopathy showed Yq microdeletions, whereas no microdeletions were found in all the other subjects, nor in male relatives of patients with deletions. Microdeletions were located in different parts of Yq, including known regions involved in spermatogenesis (DAZ and RBM, AZFa, b, and c) and other loci still poorly defined. No difference in localization of deletions was evident between cryptorchid and idiopathic patients. Microdeletions in Yq may be responsible for severe bilateral testicular damage that could be phenotypically expressed by unilateral cryptorchidism, as well as by idiopathic infertility.     

Y chromosome microdeletions and alterations of spermatogenesis,patient approach and genetic counseling

Infertility affects 15% of couples at reproductive age and human male infertility appears frequently idiopathic. The main genetic causes of spermatogenesis defect responsible for non-obstructive azoospermia and severe oligozoospermia are constitutional chromosomal abnormalities and microdeletions in the azoospermia factor region of the Y chromosome. The improvement of the Yq microdeletion screening method gave new insights in the mechanism responsible for the genesis of Yq microdeletions and for the consequences of the management of male infertility and genetic counselling in case of assisted reproductive technology.     

Identification of tumor suppressor loci on the long arm of chromosome 5 in pulmonary large cell neuroendocrine carcinoma

BACKGROUND: A recent cytogenetic analysis of non-small cell lung cancer revealed hot-spot regions for deletion on the long arm of chromosome 5 and suggested the existence of putative tumor suppressor genes in that region. However, similar studies on genetic alterations in large cell neuroendocrine carcinoma (LCNEC) have been very limited. To our knowledge, this is the first report to screen for the loss of heterozygosity (LOH) and to examine the location of putative tumor suppressor genes on chromosome 5q in LCNEC. OBJECTIVES: To identify tumor suppressor loci on chromosome 5q in LCNEC by microsatellite analysis. PATIENTS AND METHODS: Microsatellite instability and LOH in tumor and normal tissue samples from 13 patients with LCNEC, who had undergone surgical resections, were analyzed by polymerase chain reaction using a panel of 19 microsatellite DNA markers spanning chromosome 5q. RESULTS: LOH was found in all of the 13 tumors (100%) in at least one informative marker tested. The following four common minimally deleted regions were noticed on chromosome 5q: 5q14.3-q21.1; 5q22.2-q23.1; 5q23.3-q33.2; and 5q35.1-q35.2. Three of 13 individual tumors (23.1%) exhibited shifted bands for at least one of the tested microsatellite markers. Shifted bands occurred in 6 of 224 loci (2.7%) tested. CONCLUSION: These data suggest the presence of at least four tumor suppressor loci on chromosome 5q in LCNEC, and further investigations into cloning candidate tumor suppressor genes are warranted.     

Unusual findings in two patients with acquired deletions of the long arm of chromosome 5 (5q-)

Two patients with acquired deletions of the long arm of chromosome 5 (5q-) are presented and discussed. For both, clinical and other laboratory tests are highly atypical of patients with haematological malignancy characterized by 5q-. These unusual presentations of the 5q- anomaly further emphasize the heterogeneity of clinical presentations associated with this acquired chromosomal abnormality.     

Maturational and hormonal influences on Sertoli cell function

The maturation of Sertoli cell function was studied by observing properties of cells obtained from 15-, 25-, and 35-day-old rats after 3 days in culture gamma-Glutamyl transpeptidase activity, expressed per mg DNA or per mg protein, and total and soluble protein to DNA ratios increased with age. In contrast, lactate dehydrogenase activity was unchanged between 15 and 35 days of age. Secreted protein to DNA ratios and the secretion of lactate, androgen-binding protein (ABP), and transferrin per mg DNA also increased with age. Two-dimensional electrophoresis maps of [35S]methionine-labeled secretory proteins indicated the appearance of two specific bands [mol wt, 66,000; pI 6.0-6.8 (band 1); mol wt, 56,000; pI 5.3-6.0 (band 2)] between 15 and 35 days of age. The hormone dependence of these parameters was studied in Sertoli cells isolated from rats hypophysectomized at 20 days of age and subsequently treated with oil, testosterone propionate, or testosterone propionate plus FSH for 15-21 days. Hypophysectomy decreased total, soluble, and secreted protein to DNA ratios; hormone treatment in vivo increased these ratios compared to oil treatment. gamma-Glutamyl transpeptidase activity was significantly decreased by hypophysectomy and increased, compared to oil treatment, by hormone treatment. In contrast, lactate dehydrogenase activity per mg DNA was also decreased by hypophysectomy, but was unaffected by hormone treatment. [35S]Methionine incorporation into secreted protein and secretion of ABP and lactate per mg DNA were all decreased by hypophysectomy, whereas transferrin secretion per mg DNA was unaffected. While the hormone treatments increased ABP secretion, they had no effect on lactate or transferrin secretion, expressed per mg DNA. The [35S]methionine-labeled secretory proteins (bands 1 and 2) were not visible in two-dimensional electrophoresis maps after hypophysectomy of the donor animals. Treatment with testosterone propionate or testosterone propionate plus FSH in vivo resulted in the appearance of the acidic components of band 2. These data demonstrate that changes reflecting in vivo maturational patterns and hormonal influences on Sertoli cell function persist, at least in a relative sense, after 3 days in culture. Although the majority of [35S]methionine-labeled Sertoli cell cellular and secretory proteins were present under all conditions, maturation- and hormone-dependent changes in a number of specific functions were demonstrated.     

Human urokinase gene is located on the long arm of chromosome 10.

Urokinase is one of the two plasminogen activators that catalyze the conversion of inactive plasminogen to plasmin. By combining somatic cell genetics, in situ hybridization, and Southern hybridization, we localized the human urokinase gene on the distal third of the long arm (q24-qter) of chromosome 10.     

Loss of heterozygosity on long arm of chromosome 22 in sporadic colorectal carcinoma

AIM：The loss of heterozygosity(LOH)on tumor suppressor genes is believed to play a key role in carcinogenesis of colorectal cancer.In this study,we analyzed the LOHat5loci on the 1ong arm of chromosome22in sporadic colorectal cancer to identify additional loci involved in colorectal tumorigenesis.METHODS:Five poly morphic microsatellite markers were analyzed in 83cases of colorectal and normal DNAby PCR.PCRproducts were eletrophoresed on an ABI377DNA sequencer;Genescan3.1and Genotype2.1software were used for LOH scanning and analysis.Comparison between LOH frequency and clinicopathological data were performed by X^2test.P&lt;0.05was considered as statistically significant.RESULTS:The average LOHfrequency on chromosome 22q was 28.38%.The region between markers D22S280and D22S274(22q12.2-q13.33)exhibited relatively high LOH frequency.The two highest LOH loci with frequencies of 35.09%and 34.04%was identified on D22S280(22q12.2-12.3)and D22S274(22q13.32-13.33).8cases showed LOH at allinformative loci,suggesting that one chromosome 22q had been completely lost.On D22S274locus.LOH frequency of rectal cancer was50%(9/18),which was higher than that of proximal colon cancer(12%,2/17)(P=0.018).The frequency of distal colon cancer was 42%(5/12).also higher than that of proximal colon cancer.But there was no statistical significance.Putting both the tumors in distal colon and rectm together into consideration.the frequency,47%(14/30),was higher than that of proximal colon cancer(P=0.015),suggesting the mechanism of carcinogenisis was diffenent in both groups.CONCLUSIONS:This study provided evidence for the involvement of putative tumor suppressor genes related to the sporadic colorectal carcinoma on chromosome 22q.The tumor-suppressor-gene(s)might locate on the 22q12.2-12.3and/or 22q13.32-13.33.     

Inhibin B: a marker for the functional state of the seminiferous epithelium in patients with azoospermia factor C microdeletions

Testicular production of inhibin B is believed to be dependent on the presence of germ cells within the seminiferous tubules. However, this association has recently been questioned in patients with deletions of azoospermia factor (AZF) on the Y chromosome. We have addressed this problem in 442 unselected infertile/subfertile patients (excluding obstructive and iatrogenic forms) who were analyzed for Yq microdeletions. AZFc microdeletions were found in 16 patients (3.8% of the total infertile group, but 9% of the subgroup with azoospermia or severe oligozoospermia with sperm concentration <1 x 10(6)/ml). The reproductive hormone profiles in patients with AZFc microdeletions were analyzed and compared with those in infertile patients without microdeletions and those in fertile control individuals. The mean serum inhibin B concentration in the patients with AZFc microdeletions (39.5 +/- 36.0 pg/ml) was significantly lower than that in the group of infertile patients without microdeletions (134.6 +/- 88.5 pg/ml). However, no significant difference was found compared with that in a matched group of infertile patients with comparably low sperm counts (72.6 +/- 75.5 pg/ml). Bilateral testicular biopsies in the AZFc-deleted patients revealed a variable histological pattern suggestive of a progressive depletion of seminiferous epithelium. An association between testicular pathology and the reproductive hormone profile was found; the more severe forms had lower inhibin B and higher FSH levels. Importantly, if Sertoli cell-only tubules were prevalent in the biopsy, inhibin B was invariably undetectable. In patients with bilateral spermatocytic arrest, inhibin B remained within the normal range, which is consistent with a role of spermatocytes in the maintenance of inhibin B secretion. Our data support the view that, in contrast to recently published data, in patients with AZF microdeletions the serum concentration of inhibin B is dependent upon the functional interaction between Sertoli cells and spermatocytes and/or spermatids.     

Partial trisomy of the long arm of chromosome 1 in myelofibrosis and polycythemia vera

We have identified partial trisomy 1q in 2 patients with different hematologic disorders. The first patient was a 55-year-old female with myelosclerosis and myeloid metaplasia diagnosed at age 38 years presenting with anemia, fatigue, bruising, fever, and splenomegaly. At age 56, she had 50–95% myeloblast cells and 95–100 nucleated RBC precursors per 100 WBC. Chromosome analysis of unstimulated leukocytes with Q, G, and C banding showed 46,XX,-6,+t(1;6) (q25;p22) in all metaphase cells. In vitro incorporation of Fe⁵⁵ was demonstrated in 90% of metaphases by autoradiography. The second patient, a 49-year-old male, was diagnosed as having polycythemia vera at age 30 during a regular checkup. He since developed hepatosplenomegaly. Chromosome analysis from a direct bone marrow preparation at age 44 and 45 showed grossly normal karyotypes. At age 49, his marrow by Q and G banding showed almost 100% of cells with 46,XY,–13,+t(1;13) (q12;p12). Eleven cases of trisomy of 1q have been reported in various hematologic disorders. It is apparent that partial trisomy 1q represents another nonrandom chromosomal abnormality, in addition to the most common nonrandom chromosomal aberrations, such as the Philadelphia chromosome, trisomy 8, trisomy 9, and monosomy 7 in hematologic disorders.     

Molecular characterization of chromosome 7 long arm deletions in myeloid disorders

Partial deletion of the long arm of chromosome 7 is a common abnormality in the bone marrow cells of patients with myelodysplastic syndrome (MDS) or acute nonlymphocytic leukemia (ANLL). This study was undertaken to characterize the chromosome breakpoints in molecular terms and to determine if hemizygosity or submicroscopic deletions occur in patients without any cytogenetically detectable abnormality of chromosome 7. We studied restriction fragment length polymorphisms with 10 chromosome 7-specific DNA probes in separated WBC fractions. No molecular abnormalities occurred in lymphocyte-derived DNA. Several probes located in band 7q22 or distally thereof detected deletion of one allele in granulocyte-derived DNA from all four patients with chromosome 7 long arm deletion. In the granulocytes of one patient heterozygosity for the T cell receptor beta chain gene (in band 7q35) indicated that the deletion was interstitial. NJ-3, a proalpha2(I)collagen gene probe (in band 7q21-22) detected heterozygosity in the granulocytes of one patient. No hemizygosity or deletions were found in four patients with two normal chromosomes 7. These results confirm that mature granulocytes but not lymphocytes are derived from the abnormal clone. Interstitial deletions exist, and the extent of deleted genomic material varies among patients.     

Acquired partial deletions of the long arm of chromosome 5 in hematologic disorders

We have analyzed the data on 105 patients reported with a deletion of part of the long arm of chromosome 5 in the presence of hematologic disease. The major conditions associated with this abnormality are refractory anemia, polycythemia vera, and acute myelogenous leukemia, as well as the occasional occurrence of several other problems.