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Abstract: Introduction: The isolated haploinsufficiency of the SHOX gene is one of the most common cause of short stature determined by monogenic mutations. The heterozygous deviation of the gene can be detected in 2–15% of patients with idiopathic short stature (ISS), in 50–90% of patients with Leri-Weill dyschondrosteosis syndrome (LWS), and in almost 100% of patients with Turner syndrome. Aim: The aim of our study was to evaluate the frequency of SHOX gene haploinsufficiency in children with ISS, LWS and in patients having Turner syndrome phenotype (TF), but normal karyotype, and to identify the dysmorphic signs characteristic for SHOX gene deficiency. Method: A total of 144 patients were included in the study. Multiplex Ligation-dependent Probe Amplification (MLPA) method was used to identify the SHOX gene haploinsufficiency. The relationships between clinical data (axiological parameters, skeletal disorders, dysmorphic signs) and genotype were analyzed by statistical methods. Results: 11 (7.6%) of the 144 patients showed SHOX gene deficiency with female dominance (8/11, 81% female). The SHOX positive patients had a significantly higher BMI (in 5/11 vs. 20/133 cases, p

Cancer patients have a 2–7 fold increased risk of venous thromboembolism compared with the general population and, since 1990, this is associated with significant morbidity and mortality. This review summarizes the current knowledge on venous thromboembolism and cancer. Notably, the risk of venous thromboembolism varies depending on the type and stage of cancer. For instance, pancreatic and brain cancer patients have a higher risk of venous thromboembolism than breast and prostate cancer patients. Moreover, patients with metastatic disease have a higher risk than those with localized tumors. Tumor-derived procoagulant factors, cytokines and growth factors may directly and indirectly enhance venous thromboembolism. Chemotherapy produces ~6,5 fold increase in venous thromboembolism incidence in cancer patients compared to the general population. Prevention of this complication is challenging. The authors review the development of guidelines concerning venous thromboembolism prevention in hospitalized and also in ambulatory cancer patients treated with chemotherapy. Current guidelines recommend the use of low-molecular-weight heparin. Understanding the underlying mechanisms may allow the development of new therapies to safely prevent venous thromboembolism in cancer patients. Orv. Hetil., 2016, 157(6), 203–211.

International audience; Emerging evidence from murine studies suggests that mammalian sex determination is the outcome of an imbalance between mutually antagonistic male and female regulatory networks that canalize development down one pathway while actively repressing the other. However, in contrast to testis formation, the gene regulatory pathways governing mammalian ovary development have remained elusive. We performed exome or Sanger sequencing on 79 46,XX SRY-negative individuals with either unexplained virilization or with testicular/ovotesticular disorders/differences of sex development (TDSD/OTDSD). We identified heterozygous frameshift mutations in NR2F2, encoding COUP-TF2, in three children. One carried a c.103_109delGGCGCCC (p.Gly35Argfs∗75) mutation, while two others carried a c.97_103delCCGCCCG (p.Pro33Alafs∗77) mutation. In two of three children the mutation was de novo. All three children presented with congenital heart disease (CHD), one child with congenital diaphragmatic hernia (CDH), and two children with blepharophimosis-ptosis-epicanthus inversus syndrome (BPES). The three children had androgen production, virilization of external genitalia, and biochemical or histological evidence of testicular tissue. We demonstrate a highly significant association between the NR2F2 loss-of-function mutations and this syndromic form of DSD (p = 2.44 × 10-8). We show that COUP-TF2 is highly abundant in a FOXL2-negative stromal cell population of the fetal human ovary. In contrast to the mouse, these data establish COUP-TF2 as a human "pro-ovary" and "anti-testis" sex-determining factor in female gonads. Furthermore, the data presented here provide additional evidence of the emerging importance of nuclear receptors in establishing human ovarian identity and indicate that nuclear receptors may have divergent functions in mouse and human biology.

The isolated haploinsufficiency of the SHOX gene is one of the most common cause of short stature determined by monogenic mutations. The heterozygous deviation of the gene can be detected in 2-15% of patients with idiopathic short stature (ISS), in 50-90% of patients with Leri-Weill dyschondrosteosis syndrome (LWS), and in almost 100% of patients with Turner syndrome.The aim of our study was to evaluate the frequency of SHOX gene haploinsufficiency in children with ISS, LWS and in patients having Turner syndrome phenotype (TF), but normal karyotype, and to identify the dysmorphic signs characteristic for SHOX gene deficiency.A total of 144 patients were included in the study. Multiplex Ligation-dependent Probe Amplification (MLPA) method was used to identify the SHOX gene haploinsufficiency. The relationships between clinical data (axiological parameters, skeletal disorders, dysmorphic signs) and genotype were analyzed by statistical methods.11 (7.6%) of the 144 patients showed SHOX gene deficiency with female dominance (8/11, 81% female). The SHOX positive patients had a significantly higher BMI (in 5/11 vs. 20/133 cases, p0.02) and presented more frequent dysmorphic signs (9/11vs 62/133, p = 0.02). Madelung deformity of the upper limbs was also significantly more frequent among the SHOX positive patients (4/11, i.e. 36%, vs. 14/133, i.e. 10%, p = 0.0066). There were no statistically significant differences between the mean age, mean height and auxological measurements (sitting height/height, arm span/height) between the two groups of patients.The occurrence of SHOX gene haploinsufficiency observed in our population corresponds to the literature data. In SHOX positive patients, in addition to short stature, the dysmorphic signs have a positive predictive value for SHOX gene alterations. However, the SHOX deletion detected in a patient with idiopathic short stature without dysmorphic signs suggest that SHOX deletion analysis can be recommended in patients with ISS. Orv Hetil. 2017; 158(34): 1351-1356.

Cancer patients have a 2-7 fold increased risk of venous thromboembolism compared with the general population and, since 1990, this is associated with significant morbidity and mortality. This review summarizes the current knowledge on venous thromboembolism and cancer. Notably, the risk of venous thromboembolism varies depending on the type and stage of cancer. For instance, pancreatic and brain cancer patients have a higher risk of venous thromboembolism than breast and prostate cancer patients. Moreover, patients with metastatic disease have a higher risk than those with localized tumors. Tumor-derived procoagulant factors, cytokines and growth factors may directly and indirectly enhance venous thromboembolism. Chemotherapy produces ~6,5 fold increase in venous thromboembolism incidence in cancer patients compared to the general population. Prevention of this complication is challenging. The authors review the development of guidelines concerning venous thromboembolism prevention in hospitalized and also in ambulatory cancer patients treated with chemotherapy. Current guidelines recommend the use of low-molecular-weight heparin. Understanding the underlying mechanisms may allow the development of new therapies to safely prevent venous thromboembolism in cancer patients.

A kórházban kezelt sebészeti és belgyógyászati betegekben jelentős a vénásthromboembolia-rizikó. Profilaxis nélkül, a műtét típusától függően, a sebészeti beavatkozások kapcsán a betegek 15–60%-ában alakul ki mélyvénás trombózis vagy tüdőembólia, és az utóbbi ma is vezető kórházi halálok. Bár a vénás thromboemboliát leggyakrabban a közelmúltban végzett műtéttel vagy traumával hozzák kapcsolatba, a szimptómás thromboemboliás események 50–70%-a és a fatális tüdőembóliák 70–80%-a nem a sebészeti betegekben alakul ki. Nemzetközi és hazai felmérések alapján a nagy kockázattal rendelkező sebészeti betegek többsége megkapja a szükséges trombózisprofilaxist. Azonban profilaxis nélkül marad a rizikóval rendelkező belgyógyászati betegek jelentős része, a konszenzuson alapuló nemzetközi és hazai irányelvi ajánlások ellenére. A belgyógyászati betegek körében növelni kell a profilaxisban részesülők arányát és el kell érni, hogy trombózisrizikó esetén a betegek megkapják a hatásos megelőzést. A beteg trombóziskockázatának felmérése fontos eszköze a vénás thromboembolia által veszélyeztetett betegek felderítésének, megkönnyíti a döntést a profilaxis elrendeléséről és javítja az irányelvi ajánlások betartását. A trombózisveszély megállapításakor, ha nem ellenjavallt, profilaxist kell alkalmazni. „A thromboemboliák kockázatának csökkentése és kezelése” című, 4. magyar antithromboticus irányelv felhívja a figyelmet a vénástrombózis-rizikó felmérésének szükségességére, és elsőként tartalmazza a kórházban fekvő belgyógyászati és sebészeti betegek kockázati kérdőívét. Ismertetjük a kockázatbecslő kérdőíveket és áttekintjük a kérdőívekben szereplő rizikófaktorokra vonatkozó bizonyítékokon alapuló adatokat.

Objective Autoimmune polyendocrine syndrome type I (APS I) is a rare primary immunodeficiency disorder characterized by chronic mucocutaneous candidiasis, multi-organ autoimmunity and ectodermal dysplasia. Autoantibodies to parathyroid and adrenal glands and type I interferons (IFN) are hallmarks of APS I, which results from mutations in the autoimmune regulator (AIRE) gene. We wished to study clinical, immunological and genetic features of APS I in Hungarian patients, and to correlate anti-IFN-omega serum concentration with APS I and other multi-organ autoimmune diseases. Design Detailed analysis of patients with APS I and multi-organ autoimmune diseases. Patients Seven patients with APS I and 11 patients with multi-organ autoimmune diseases were studied. Measurements Mutational analysis was performed by bidirectional sequencing of AIRE. Antibodies against IFN-omega and endocrine organ-specific autoantigens were studied with radioimmunoassay. RFLP was performed by digestion of DNA with Hin6I restriction enzyme. Results AIRE sequence analysis revealed homozygous c.769C>T mutations in three patients and compound heterozygous sequence variants (c.769C>T/c.44_66dup26bp; c.769C>T/c.965_977del13bp; c.769C>T/c.1344delC) in four patients with APS I. All the six live patients tested had markedly elevated IFN-omega antibodies, which were not found in heterozygous siblings or parents. One of the identified patients was negative for antibodies against IFN-omega at 6 weeks of age, but became positive at 7 months. At age 1, he is still without symptoms of the disease. In contrast to patients with APS I, no AIRE mutation or elevation of IFN-omega antibodies were detected in patients with multi-organ autoimmune diseases. Conclusion This is the first overview of patients diagnosed with APS I in Hungary. A novel c.1344delC mutation in AIRE was detected. Anti-IFN-omega antibodies seem to appear very early in life and are helpful to differentiate APS I from other multi-organ autoimmune diseases.

2006-ban az ENDORSE (nemzetközi epidemiológiai nap a vénás trombózis és embólia szempontjából veszélyeztetett betegek felmérésére az akut kórházi ellátásban) nemzetközi, obszervációs, keresztmetszeti vizsgálat célja a kórházban fekvő, vénás thromboembolia veszélyének kitett betegek prevalenciájának, valamint a hatásos profilaxisban részesülők arányának meghatározása volt. A 32 ország 358 véletlenszerűen beválasztott kórházában végzett globális regiszterben kilenc magyar vizsgálóhely vett részt. A magyarországi eredmények szerint a sebészeti betegek irányelvnek megfelelő profilaxisa felülmúlta a nemzetközi átlagot, de a belgyógyászati profilaxis jelentős mértékben alulmaradt. A trombózismegelőzés összehasonlítására két év és két hónap után hazánkban elvégezték az ENDORSE-2-HUNGARIA vizsgálatot. Mindkét felmérésben az American College of Chest Physicians 2004-es evidenciákon alapuló irányelvei szerint értékelték a trombózisrizikót, és megvizsgálták, hogy a betegek megkapták-e az irányelveknek megfelelő profilaxist. Az egynapos ENDORSE-2-HUNGARIA vizsgálatot a már felmért hét kórház mellett két újonnan beválasztott kórházban ismételték meg. A kórlapok alapján összesen 886 betegnél vizsgálták meg a vénásthromboembolia-kockázat fennállását. Vénás thromboembolia szempontjából a betegek 59,0%-a volt veszélyeztetett (N=523/886), közülük a sebészeti betegek 100%-a (N=327), a belgyógyászatiak 35,1%-a (N=196). A teljes trombóziskockázatú populációnak 67,9%-a (N=355) részesült az ACCP-irányelvek szerinti profilaxisban. Az ajánlásnak megfelelő profilaxist a sebészeti betegek közül 84,4% (N=276), a belgyógyászati betegek közül 40,3% (N=79) kapta meg. Összehasonlítottuk a 2006-os és 2009-es ENDORSE-adatokat. A hatásos profilaxisban részesült trombózisrizikójú sebészeti betegek aránya nem változott szignifikánsan, a belgyógyászati betegeknél 43,9%-os szignifikáns (p=0,002) növekedést találtunk, ami bizonyítja a két vizsgálat közötti idő alatt a tényeket bemutató és a belgyógyászati profilaxis növelésére fókuszáló előadások sikerét. Az ENDORSE-2-HUNGARIA eredményei szerint 2009-ben a vénástrombózis-kockázatú belgyógyászati betegek 59,7%-a, a sebészeti betegek 15,6%-a védtelen maradt a trombózissal szemben. További erőfeszítéseket kell tehát tennünk azért, hogy még több hospitalizált beteg részesüljön profilaxisban. Az egészségügyi dolgozók körében tovább kell növelni a hospitalizált belgyógyászati betegek trombóziskockázatának ismeretét, és törekednünk kell arra, hogy még szélesebb körben alkalmazzák a profilaxist.

We screened 100 individuals with anomalies of testicular development or function for mutations in the TSPYL1 gene. A 46,XY female with complete gonadal dysgenesis carried a p.K320R mutation in the highly conserved NAP domain, and a 46,XY male with idiopathic azoospermia harbored a p.R89H mutation, and this data supports the hypothesis that mutations in TSPYL1 may contribute to anomalies of testicular development/function.

A vénás thromboembolia kockázatáról és a profilaxis alkalmazásának mértékéről világszerte hiányosak az adatok. Az ENDORSE (nemzetközi epidemiológiai nap a vénás trombózis és embólia szempontjából veszélyeztetett betegek felmérésére az akut kórházi ellátásban) az első, nemzetközi, keresztmetszeti vizsgálat, amely globális áttekintést nyújt az akut kórházi ellátásban részesülő betegek vénásthromboembolia-kockázatának prevalenciájáról, valamint a hatásos profilaxisban részesülő betegek arányáról. Harminckét ország 358 reprezentatív kórházában a kórlapok alapján felmérték a 40 éves vagy idősebb, belgyógyászati és a 18 éves vagy idősebb, sebészeti osztályon fekvő összes beteg vénásthromboembolia-kockázatát. Az American College of Chest Physicians 2004-es evidenciákon alapuló irányelvei szerint értékelték a trombózisrizikót és megvizsgálták, hogy a betegek megkapták-e az irányelveknek megfelelő profilaxist. A nemzetközi felmérésben kilenc magyarországi centrum vett részt, és hazánkban a trombóziskockázatot összesen 1300 betegnél becsülték meg. A vénás thromboembolia szempontjából veszélyeztetettek aránya 39,9% (N = 519) volt, közülük 58,2% (N = 253) volt a sebészeti és 30,8% (N = 266) a belgyógyászati beteg. A teljes trombóziskockázatú populációnak 56,6%-a (294 beteg) részesült az ACCP-irányelvek szerinti profilaxisban. Az ajánlásnak megfelelő profilaxist a sebészeti betegek közül 86,6% (N = 219), a belgyógyászati betegek közül csak 28,2% (N = 75) kapta meg. Hazánkban tehát a hospitalizált, vénás trombózis által veszélyeztetett belgyógyászati betegek több mint kétharmada megfelelő profilaxis nélkül maradt. Az ENDORSE felmérés megerősíti, hogy a kórházi, belgyógyászati és sebészeti betegek nagy részénél világszerte, így hazánkban is vénástrombózis-veszély áll fenn, így sürgősen cselekednünk kell annak érdekében, hogy a veszélyeztetett betegek megfelelő profilaxist kapjanak.

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a rare recessive disorder that results in several autoimmune diseases due to the mutations in the AIRE (autoimmune regulator) gene. APECED patients develop several autoimmune endocrine disorders and are characterized by the high titer autoantibodies to organ-specific antigens such as the steroidogenic P450 cytochromes. So far, 38 mutations have been identified in the AIRE gene. We report here the genetic and autoantibody analysis of 27 APECED patients of Eastern and Central European origins and one Egyptian patient. From 54 analyzed APECED chromosomes, eight mutations were detected, four of which (T16M, W78R, IVS1_IVS4, 30-53dup23bp) are novel. The most prevalent reason for APECED in these populations was the occurrence of R257X (36 chromosomes) that has been described earlier as a common and recurrent mutation in several other populations. The analysis of humoral immunity to steroidogenic P450 cytochromes by the immunoblotting of E. coli expressed antigens in the 18 APECED patients showed that 67%, 44%, and 61% of the Eastern and Central European APECED patients had autoantibodies to P450c17, P450c21, and P450scc, respectively.

Microdeletions of the long arm of the human Y chromosome are associated with spermatogenic failure and have been used to define three regions of Yq (AZFa, AZFb, and AZFc) that are recurrently deleted in infertile males. In a blind study we screened 131 infertile males (46 idiopathic and 85 nonidiopathic) for Y chromosome microdeletions. Nineteen percent of idiopathic males, with an apparently normal 46,XY chromosome complement had microdeletions of either the AZFa, AZFb, or AZFc region. There was no strict correlation between the extent or location of the deletion and the phenotype. The AZFb deletions did not include the active RBM gene. Significantly, a high frequency of microdeletions (7%) was found in patients with known causes of infertility and a 46,XY chromosome complement. These included deletions of the AZFb and AZFc regions, with no significant difference in the location or extent of the deletion compared with the former group. It is recommended that all males with reduced or absence sperm counts seeking assisted reproductive technologies be screened for deletions of the Y chromosome.

Denys-Drash and Frasier syndromes are rare human disorders that associate nephropathy with gonadal and genital abnormalities. In DDS there is a predisposition to Wilms' tumor. Heterozygous point mutations in the Wilms' tumor, type1 gene (WT1), particularly those altering the zinc finger (ZF) encoding exons, have been reported in most DDS patients, while mutations in intron 9 of the same gene cause FS. This paper describes two cases of DDS, one FS and one patient with Wilm's tumor and intersex genitalia, in which mutations were searched by sequencing the exons 8 and 9 of WT1 gene. Patient 1 carried a missense point mutation in exon 8 (ZF2), converting a CGA-Arg codon to a TGA-stop codon. Patient 2 presented a single nucleotide deletion within exon 9 (ZF3) introducing a premature chain termination at codon 398. Patients 3 and 4 had a C-->T transition at position +4 of the second alternative splice donor site of exon 9 (this mutation was detected in peripheral blood and in tumor derived DNA of patient 3). However, patient 3 had previously developed a Wilms' tumor. This is the first case of Wilms' tumor development in a phenotypically and genetically confirmed case of FS.

A de novo apparently balanced translocation involving chromosomes 8 and 20 was found in a 14-year-old boy with minor anomalies, mild skeletal abnormalities and ambiguous external genitalia including perineoscrotal hypospadias, rudimentary fused labioscrotal folds, bilateral cryptorchidism, and small penis. The karyotype was 46,XY, t(8;20)(q22.3-23;p13). No signs of other conditions known to be associated with structural anomalies of either chromosome 8 or 20 were present and incomplete masculinisation of the external genitalia appears to be the main component of the phenotype. Clinical and biological studies showed apparently normal testicular function in utero and after birth. Examinations excluded 5{alpha}-reductase deficiency or a block in any enzymatic steps of testosterone, glucocorticoid and mineralocorticoid biosynthesis. Coding sequences of the sex-determining gene (SRY) and androgen receptor gene (AR) were found to be identical to those of a normal male excluding their role in the cause of the present condition. Since several other reports describe the association of hypospadias and hypertelorism with deletions or translocations involving 8q, we suggest that a locus necessary for male sex differentiation is located at distal 8q. 24 refs., 3 figs.

A szerzők 46,XY tiszta gonáddiszgenezis (Swyer-szindróma) esetük kórtörténetét mutatják be. A Swyer-szindróma jellemzői a 46,XY karyotypus, primer amenorrhoea, női belső nemi szervek, kétoldali csíkgonád és a női fenotípus. A szindróma számos jól ismert gén mutációjával áll összefüggésben, amelyek szerepet játszanak a heredifferenciálódás kaszkádjában. SRY-génmutáció csak 10–15%-ban fordul elő, az esetek többségében a nemi differenciálódásban szerepet játszó más gének hibái okozzák a kórképet. Esetbemutatás: A 16 éves leány primer amenorrhoea miatt kereste fel az endokrinológiai részleget. Fizikális vizsgálattal női fenotípust észleltek, magassága 166 cm, testsúlya 56,5 kg volt, az emlők és a genitális szőrzet fejlődése Tanner-I., illetve -II. stádiumnak felelt meg. A külső nemi szervei női típusúak voltak. Kismedencei MRI hypoplasiás uterust és mindkét oldalon 5×10 mm méretű petefészket mutatott ki. A kromoszómavizsgálat 46,XY karyotypust igazolt. Az SRY és SF1 gének vizsgálata nem bizonyított mutációt vagy deletiót. A szérum folliculusstimuláló hormon és a luteinizáló hormon koncentrációi emelkedettek voltak. A szérumtumormarker-vizsgálat nem mutatott ki kóros eltérést. A diagnózis megállapítása után profilaktikus gonadectomiát végeztek, a szövettani vizsgálat kétoldali csíkgonádot igazolt. A műtét után bevezetett hormonpótló kezelésre a szekunder nemi jelek fejlődésnek indultak, és 1,5 év múlva menarche jelentkezett. Következtetések: A szerzők hangsúlyozzák, hogy serdülőkorban primer amenorrhoea esetén mindig el kell végezni a karyotypus-vizsgálatot. A diagnózis megállapítása után a diszgenetikus gonádok eltávolítása javasolt a malignus elfajulás veszélye miatt. Orv. Hetil., 2010, 48, 1991–1995.

A large proportion of hospitalized surgical and medical patients are at risk for venous thromboembolism. Depending on the type of surgical intervention, venous thrombosis develops in 15-60% of surgical patients without prophylaxis. Although venous thromboembolism is most often considered to be associated with recent surgery or trauma, 50 to 70% of symptomatic thromboembolic events and 70 to 80% of fatal pulmonary embolisms occur in nonsurgical patients. International and national registries show that the majority of at-risk surgical patients actually received the appropriate thromboembolic prophylaxis. However, despite of international and national recommendations, prophylaxis was not provided for a large proportion of at-risk medical patients. The rate of medical patients receiving prophylaxis should be increased, and appropriate thrombosis prophylaxis should be offered to at-risk medical patients. The thrombosis risk assessment is an important tool to identify patients at increased risk for venous thromboembolism, to simplify decision making on prophylaxis administration, and to improve the adherence to guidelines. When the risk is recognized, if there is no contraindication, prophylaxis should be ordered. The 4th Hungarian Antithrombotic Guideline entitled "Risk reduction and treatment of thromboembolism" calls attention to the importance of risk assessment and for the first time it includes and recommends risk assessment models for hospitalized surgical and medical patients. The risk assessment models are presented and the evidence based data for the different risk factors included in these models are reviewed.

The aim of the safety analysis performed by Chinoin Drug Safety Unit was to summarise the safety profile of NO-SPA (drotaverine hydrochloride), the Hungarian spasmolytic well known in Hungary and abroad. Authors collected the safety data from clinical studies between 1964-1998 for the determination of the adverse event frequency. Based on the data of 12111 patients treated with NO-SPA in 37 clinical trials 0.9% frequency of adverse events was found. The value indicates uncommon (0.1-1%) adverse event frequency according to the criteria for frequency categories. The benefit-risk ratio of NO-SPA is favourable, since the therapeutic effect does not include frequent adverse reaction occurrence.

A case of a true hermaphrodite presenting with a karyotype of 46,X,del(X)(p21.1-->pter) is described. The testis-determining gene, SRY, was not detected in DNA prepared from either peripheral blood lymphocytes or from a gonad biopsy. The patient also presented with a series of discrete somatic abnormalities, including abnormal skin and retinal pigmentation, and mental retardation. The extent of the Xp deletion was mapped by Southern blotting. X chromosome replication studies of lymphoblast cells prepared from the patient indicated that the deleted X chromosome was inactivated in all cells examined. It is suggested that the phenotype of the patient is caused by the unmasking of a recessive allele(s) on the grossly intact X chromosome. The relationship between the Xp deletion, the intersex phenotype, and the possible role of an Xp locus involved in human sex determination is discussed.

Microdeletions of the long arm of the human Y chromosome are associated with spermatogenic failure and have been used to define three regions of Yq (AZFa, AZFb, and AZFc) that are recurrently deleted in infertile males. In a blind study we screened 131 infertile males (46 idiopathic and 85 nonidiopathic) for Y chromosome microdeletions. Nineteen percent of idiopathic males, with an apparently normal 46,XY chromosome complement had microdeletions of either the AZFa, AZFb, or AZFc region. There was no strict correlation between the extent or location of the deletion and the phenotype. The AZFb deletions did not include the active RBM gene. Significantly, a high frequency of microdeletions (7%) was found in patients with known causes of infertility and a 46,XY chromosome complement. These included deletions of the AZFb and AZFc regions, with no significant difference in the location or extent of the deletion compared with the former group. It is recommended that all males with reduced or absence sperm counts seeking assisted reproductive technologies be screened for deletions of the Y chromosome.