Disruption of the ATE1 and SLC12A1 Genes by Balanced Translocation in a Boy with Non-Syndromic Hearing Loss

We report on a boy with non-syndromic hearing loss and an apparently balanced translocation t(10;15)(q26.13;q21.1). The same translocation was found in the normally hearing brother, father and paternal grandfather; however, this does not exclude its involvement in disease pathogenesis, for example, by unmasking a second mutation. Breakpoint analysis via FISH with BAC clones and long-range PCR products revealed a disruption of the arginyltransferase 1 (ATE1) gene on translocation chromosome 10 and the solute carrier family 12, member 1 gene (SLC12A1) on translocation chromosome 15. SNP array analysis revealed neither loss nor gain of chromosomal regions in the affected child, and a targeted gene enrichment panel consisting of 130 known deafness genes was negative for pathogenic mutations. The expression patterns in zebrafish and humans did not provide evidence for ear-specific functions of the ATE1 and SLC12A1 genes. Sanger sequencing of the 2 genes in the boy and 180 GJB2 mutation-negative hearing-impaired individuals did not detect homozygous or compound heterozygous pathogenic mutations. Our study demonstrates the many difficulties in unraveling the molecular causes of a heterogeneous phenotype. We cannot directly implicate disruption of ATE1 and/or SLC12A1 to the abnormal hearing phenotype; however, mutations in these genes may have a role in polygenic or multifactorial forms of hearing impairment. On the other hand, it is conceivable that our patient carries a disease-causing mutation in a so far unidentified deafness gene. Evidently, disruption of ATE1 and/or SLC12A1 gene function alone does not have adverse effects.

FTO and INSIG2 Genotyping Combined with Metabolic and Anthropometric Phenotyping of Morbidly Obese Patients

Obesity is a major health problem worldwide. Associations of obesity with common variants of the fat mass- and obesity-associated gene (FTO) and insulin-induced gene 2 (INSIG2) have been reported in various studies. We aimed to further investigate the association of 2 single nucleotide polymorphisms (SNPs), rs9939609 in FTO and rs7566605 in INSIG2, with body mass index (BMI) and other anthropometric and metabolic parameters in subjects with morbid obesity (BMI ≥40). SNPs rs9939609 and rs7566605 were genotyped in 124 unrelated morbidly obese patients (mean BMI = 50, range 40.1-77.1) from Mainz, Germany, and in 253 normal controls without a history of morbid obesity. Metabolic and anthropometric parameters were analyzed in 109 of the 124 patients, and associations with the genotype data were examined. The high-risk AA genotype for FTO rs9939609 was observed in 32.3% of patients versus 15.8% of controls (p = 0.0004) and was associated with an increased obesity risk [odds ratio (OR) = 2.54, 95% confidence interval (CI) = 1.53-4.21]. The intermediate-risk AT genotype was found in patients and controls at similar frequencies (48.4 vs. 48.6%, OR = 0.99). The low-risk TT genotype for rs9939609 was found in 19.4% of patients (35.5% of controls; p = 0.0013) and was associated with a decreased risk for morbid obesity (OR = 0.43, CI = 0.26-0.73). In contrast, INSIG2 rs7566605 showed no association with obesity in our patients. Evaluation of metabolic data indicated associations between the high-risk FTO genotype (rs9939609_AA) and increased levels of serum glutamic oxaloacetic transaminase (GOT) and between the high-risk INSIG2 genotype (rs7566605_CC) and lower waist-to-hip ratio and lower hemoglobin A1c (HbA1c) levels. Our results confirm an association of the FTO SNP with extreme obesity. However, we found no association of the potential obesity risk allele of INSIG2 in our sample and thus cannot confirm an association of the INSIG2 CC genotype with obesity. We identified an association between the high-risk FTO genotype (rs9939609_AA) and higher GOT levels, which could possibly reflect the increased frequency of nonalcoholic steatohepatitis with obesity. We also detected associations of the high-risk INSIG2 genotype (rs7566605_CC) with lower waist-to-hip ratios and lower HbA1c levels, which may indicate amelioration of impaired glucose tolerance and type 2 diabetes for patients with this genotype after bariatric surgery.

Novel VANGL1 Gene Mutations in 144 Slovakian, Romanian and German Patients with Neural Tube Defects

Neural tube defects (NTDs) are a group of congenital malformations of the central nervous system occurring at an average rate of 1 per 1,000 human pregnancies worldwide. Numerous genetic and environmental factors are discussed to be relevant in their etiology. In mice, mutants in >200 genes including the planar cell polarity (PCP) pathway are known to cause NTDs, and recently, heterozygous mutations in the human VANGL1 gene have been described in a small subset of patients with NTDs. We performed a VANGL1 mutation analysis in 144 unrelated individuals with NTDs from Slovakia, Romania and Germany and identified 3 heterozygous missense mutations: c.613G>A (p.Gly205Arg) with an open spina bifida (lumbosacral meningomyelocele), c.557G>A (p.Arg186His) with a closed spina bifida (tethered cord and spinal lipoma) and c.518G>A (p.Arg173His) with an unknown NTD. The c.613G>A mutation was also found in a healthy sibling. None of the mutations were described previously. Findings support that heterozygous VANGL1 mutations represent hypomorphs or conditional mutants predisposing to NTDs and occur at a frequency of approximately 2.1% of open and closed spinal NTDs. The mutations (p.Arg173His, p.Arg186His, p.Gly205Arg) modified conserved regions of the VANGL1 protein and shared similarities with previously described mutants, providing further evidence for the presence of mutational hot spots in these patients.

A boy with classical Rubinstein-Taybi syndrome but no detectable mutation in the CREBBP and EP300 genes

Rubinstein-Taybi syndrome (RTS) is a rare autosomal dominant genetic disorder and is characterized by mental retardation, distinctive facial features, broad and often angulated thumbs and great toes. We report on a 7 year old boy with classical Rubinstein-Taybi syndrome. His facial and clinical features were very typical, including broad thumbs with radial angulation and broad great toes. Rigorous genetic analysis of the CREBBP and EP300 genes using DNA sequencing and multiple ligation-dependent probe amplification (MLPA) revealed no causative mutation in this boy, only a hitherto unreported but paternally inherited heterozygous sequence alteration, c.506 1+9C>T in IVS 30-31, which most likely represents a normal variant (NetGene 2 splice prediction software). We question if this boy could have a hitherto undetectable mutation type.

Prenatal diagnosis of a recombinant chromosome 7 resulting in trisomy 7q11.22 --> qter

Prenatal diagnosis of trisomy 7 is complex due to only a few reported cases. We report here on a stillborn boy with very large duplication of 7q11.22 --> qter, encompassing almost the entire long arm of chromosome 7. Ultrasound, fetal and parental chromosome banding, fluorescence in situ hybridization (FISH), and array comparative genomic hybridization (CGH) analyses were performed. Sonographic findings included growth retardation, micrognathia, ventricular septal defect (VSD), aortic coarctation, bradyarrhythmia, pericardial effusion, bilateral hydronephrosis, infravesical obstruction, and cerebellar hypoplasia. Chromosome analysis after cordocentesis at 23 weeks of gestation revealed an abnormal male karyotype with 46 chromosomes and a derivative chromosome 7 with a very large duplication of the long arm, 46,XY,der(7)(qter --> q11.2::p22 --> qter). The mother was found to carry an apparently balanced pericentric inversion, 46,XX,inv(7)(p22q11.2). Thus, the recombinant chromosome 7 [rec(7)dup(7q)inv(7)(p22.3q11.22)mat] of the fetus must have arisen through meiotic crossing-over between the inverted chromosome and the normal chromosome 7 in the maternal germline. FISH and array CGH results confirmed the recombinant chromosome 7 in the fetus and indicated a loss of 1.9 Mb at chromosome 7pter --> p22.3 (pter to 1,948,072 bp), and a gain of 87.04 Mb at chromosome 7q11.22 --> qter (71,760,154 bp to qter). The rare syndrome of almost complete trisomy 7q may be suspected in cases of growth retardation, cerebellar hypoplasia, micrognathia, aortic coarctation and VSD and hydronephrosis. Invasive prenatal diagnosis must be offered to the parents.

Haploinsufficiency of 16.4 Mb from chromosome 22pter-q11.21 in a girl with unilateral conductive hearing loss

We present the postnatal diagnosis of a de novo der(18)t(18;22)(p11.32;q11.21)pat, resulting in an unbalanced 45,XX,der (18)t(18;22) karyotype in a girl with conductive hearing loss on the left and ptosis of the right upper eye-lid. Unilateral ptosis was also observed in the patient's 2 years and 8 months younger sister, who grows noticeably faster and appears to be a much quicker learner. After speech therapy the patient was eventually placed in normal school. The haploinsufficient 16.4-Mb region on chromosome 22pter-->q11.21 contains 10 genes as well as many predicted genes, pseudogenes, and retrotransposed sequences with unknown functions. This observation may prove useful for prenatal diagnosis and genetic counselling of chromosome 22q11.1 gains and losses.

Epimutation at human chromosome 14q32.2 in a boy with a upd(14)mat-like clinical phenotype

Recently, three reports described deletions and epimutations affecting the imprinted region at chromosome 14q32.2 in individuals with a phenotype typical for maternal uniparental disomy of chromosome 14 [upd(14)mat]. In this study, we describe another patient with upd(14)mat-like phenotype including low birth weight, neonatal feeding problems, muscular hypotonia, motor and developmental delay, small hands and feet, and truncal obesity. Conventional cytogenetic analyses, fluorescence in situ hybridization subtelomere screening, multiplex ligation-dependent probe amplification analysis of common microdeletion and microduplication syndromes, and methylation analysis of SNRPN all gave normal results. Methylation analysis at 14q32.2 revealed a gross hypomethylation of the differentially methylated regions (intergenic DMR and MEG3-DMR). Further molecular studies excluded full or segmental upd(14)mat as well as a microdeletion within this region. Evidently, the upd(14)mat-like clinical phenotype is caused by an epimutation at 14q32.2. The clinical and molecular features of this novel case are discussed with respect to the recently published cases.

A severely mentally and motor retarded girl with monosomy 3pter-->p25 and trisomy 8q24-->qter due to a familial reciprocal translocation t(3;8)(p25;q24)

A severely mentally and motor retarded girl with monosomy 3pter--p25 and trisomy 8q24-qter due to a familial reciprocal translocation t(3;8) (p25;q24): We report a familial translocation t(3;8) in a three generation family that includes a severely retarded 9-year-old girl with intrauterine and postnatal growth retardation, microcephaly, capillary hemangiomas of the forehead and perioral region, synophrys, ptosis, long philtrum, high arched palate, micrognathia, malformed ears, clinodactyly, hypotonia, mental and motor retardation. The pedigree was highly suggestive ofa familial rearrangement. Cytogenetics and fluorescent in situ hybridization (FISH) showed an unbalanced translocation of chromosomes 3p25 and 8q24 of maternal origin, karyotype 46,XX,der(3)t(3;8)(p25q24)mat. Using FISH the breakpoint at 8q24 was located distal of TRPS1, the gene for trichorhinophalangeal syndrome. The balanced translocation was found in the mother, maternal grandmother and prenatally diagnosed brother. Ten individuals (seven miscarriages, niece, two nephews) probably also had an unbalanced translocation. Genetic counseling was given to the family. Because of the hemizygous deletion of the VHL gene at chromosome 3p25.3, the patient is at risk for von Hippel-Lindau (VHL) syndrome, predisposing to retinal, cerebellar, spinal haemangioblastomas, renal cell carcinoma, phaeochromocytoma and pancreatic tumors. Therefore, for early detection and treatment of VHL syndrome, we performed periodic screening beginning at age 5 years. A familial translocation t(3;8) is very rare and there are no previous reports on terminal monosomy 3p (pter-->p25) and terminal trisomy 8q (q24-->qter).

Rubinstein-Taybi syndrome and CREBBP c.201 202delTA mutation: a case presenting with varicella meningoencephalitis

Rubinstein-Taybi syndrome (RTS) is a rare syndrome with a frequency of approximately 1 in 125,000 affected newborns, which is characterized by mental retardation, growth retardation, a particular dysmorphology and, in a subset of cases, immunodeficiency. RTS is typically caused by CREBBP deficiency, and heterozygous mutation or deletion of the CREBBP gene has been identified in 60-70% of patients. The inheritance is autosomal dominant but reports of vertical transmission are exceedingly rare; near-all cases are caused by de novo mutations. Here we present an 8-month-old boy with varicella meningoencephalitis, RTS, and a de novo deletion of the CREBBP gene of two base pairs at position 201-202 in exon 2, c. 201 202delT. The mutation has not been described previously but it predicts a protein truncation, and truncating CREBBP mutations are typical causes of RTS.

Boy with seizures (West syndrome) and distal 7q duplication syndrome due to an unbalanced 7q;9p translocation

We report a 15 month old boy with prominent metopic suture, epicanthal folds, strabismus, low-set ears, microretrognathia, large anterior fontanel, bilateral simian creases, muscular hypotonia, and severe psychomotor retardation. He also had West syndrome. An electroencephalogram showed hypsarrythmia, and cranial MR indicated a myelinisation delay. Standard karyotyping showed additional material on one chromosome 9p. Using FISH, a terminal 7q duplication spanning 26 Mb in size and a terminal 9p deletion sized (at least) 9.1 Mb were identified. The father had a karyotype of t(7;9)(q33;p23) and the mother's karyotype was normal. The boy presented typical facial features of the distal 7q duplication syndrome but no genital anomalies attributable to his distal 9p deletion. We assume that the severe epilepsy is likely due to the trisomy 7q.

Two independent chromosomal rearrangements, a very small (550 kb) duplication of the 7q subtelomeric region and an atypical 17q11.2 (NF1) microdeletion, in a girl with neurofibromatosis

Most patients with neurofibromatosis (NF1) are endowed with heterozygous mutations in the NF1 gene. Approximately 5% show an interstitial deletion of chromosome 17q11.2 (including NF1) and in most cases also a more severe phenotype. Here we report on a 7-year-old girl with classical NF1 signs, and in addition mild overgrowth (97th percentile), relatively low OFC (10th-25th percentile), facial dysmorphy, hoarse voice, and developmental delay. FISH analysis revealed a 17q11.2 microdeletion as well as an unbalanced 7p;13q translocation leading to trisomy of the 7q36.3 subtelomeric region. The patient's mother and grandmother who were phenotypically normal carried the same unbalanced translocation. The 17q11.2 microdeletion had arisen de novo. Array comparative genomic hybridization (CGH) demonstrated gain of a 550-kb segment from 7qter and loss of 2.5 Mb from 17q11.2 (an atypical NF1 microdeletion). We conclude that the patient's phenotype is caused by the atypical NF1 deletion, whereas 7q36.3 trisomy represents a subtelomeric copy number variation without phenotypic consequences. To our knowledge this is the first report that a duplication of the subtelomeric region of chromosome 7q containing functional genes (FAM62B, WDR60, and VIPR2) can be tolerated without phenotypic consequences. The 17q11.2 microdeletion (containing nine more genes than the common NF1 microdeletions) and the 7qter duplication were not accompanied by unexpected clinical features. Most likely the 7qter trisomy and the 17q11.2 microdeletion coincide by chance in our patient.

Two complementary recombinant chromosomes 5 in a healthy woman

We report a healthy woman with two abortions who is a carrier for a rare heterozygous double recombinant of an inv(5) chromosome, karyotype 46,XX,rec(5)dup(5p) inv(5)(p13q22),rec(5)dup(5q)inv(5)(p13q22). Her father had a 46,XY,inv(5)(p13q22) karyotype; his consanguineous wife had died. Molecular investigation of 11 highly polymorphic markers spanning chromosome 5 revealed biparental inheritance for two markers (D5S406, D5S681) on 5p15.3 and 5q13.1, and an allele constellation not compatible with paternal heterodisomy for marker D5S623 on 5q11.2. Eight markers were not informative. Three mechanisms of formation are proposed: First, fertilization of a normal oocyte by a sperm carrying the two recombinant chromosomes 5, followed by postzygotic recombination between the normal maternal homologue and the rec(5)dup(5p), and by loss of the mitotically recombined maternal homologue, leading to segmental paternal heterodisomy 5q13-->qter (trisomic rescue). Second, postzygotic recombination in a 46,XX,inv(5)(p13q22) zygote resulting in the 46,XX,rec(5)dup(5p)inv(5)(p13q22),rec(5) dup(5q)inv(5)(p13q22) karyotype, followed by absence of the original cell line in lymphocytes. Third and most likely, both parents were inv(5) carriers and complementary recombinations in maternal and paternal meiosis resulted in a zygote with two recombinant chromosomes 5. Our patient refused any further studies but later reported the birth of a phenotypically normal child. This is the first report known to us of complementation by two non-homologous recombinant chromosomes in a phenotypically normal woman, and the first example of a child born to a carrier of complementary recombinant chromosomes.

Three patients with 9p deletions including DMRT1 and DMRT2: A girl with XY complement, bilateral ovotestes, and extreme growth retardation, and two XX females with normal pubertal development

It is well documented that distal 9p monosomy can be associated with XY sex reversal. Recently, the possibility of DMRT1 and/or DMRT2 (the genes for doublesex and mab-3 related transcription factor 1 and 2) being the sex determining genes(s) at 9p has been raised. DMRT1 and DMRT2 map near the 9p telomere, distal of marker D9S1779. We describe here three unrelated females with distal 9p monosomy, one with XY complement and two with XX complements. In each individual, fluorescent in situ hybridization predicted the loss of the DMRT genes. Patient 1, an XY individual with monosomy 9pter --> p24.1 approximately 24.2 and trisomy 7q32 --> qter had normal female external genitalia, a blind ending vagina, no uterus, a Fallopian tube on the right, and bilateral ovotestes with primitive ovarian tissue. She also had extreme growth retardation. Around 80 cases of distal 9p monosomy have been reported previously, but there has been no report of ovotestes or gonads comprising ovarian tissue in a XY patient with 9p deletion. Findings in Patient 1 suggest that the phenotypic spectrum of the heterozygous DMRT deletion may include true hermaphroditism. Patients 2 and 3 were 12- and 14-year-old females with XX complements, normal external genitalia, and normal pubertal development. Patient 2 had pure monosomy 9pter --> p23 and Patient 3 had monosomy 9pter --> p22.3 approximately 23 combined with trisomy 3pter --> p23 approximately 24. To date, detailed reports on the gonadal status of XX 9p-females have been limited to prepubertal girls. Patients 2 and 3 are the first females reported to have distal 9p monosomy and a normal puberty.

Microphthalmia with linear skin defects syndrome (MLS): a male with a mosaic paracentric inversion of Xp

The microphthalmia with linear skin defects syndrome (MLS) is an X-linked dominant disorder with male lethality. In the majority of the patients reported, the MLS syndrome is caused by segmental monosomy of the Xp22.3 region. To date, five male patients with MLS and 46,XX karyotype ("XX males") have been described. Here we report on the first male case with MLS and an XY complement. The patient showed agenesis of the corpus callosum, histiocytoid cardiomyopathy, and lactic acidosis but no microphthalmia, and carried a mosaic subtle inversion of the short arm of the X chromosome in 15% of his peripheral blood lymphocytes, 46,Y,inv(X)(p22.13 approximately 22.2p22.32 approximately 22.33)[49]/46,XY[271]. By fluorescence IN SITU hybridization (FISH), we showed that YAC 225H10 spans the breakpoint in Xp22.3. End-sequencing and database analysis revealed a YAC insert of at least 416 kb containing the genes HCCS and AMELX, and exons 2-16 of ARHGAP6. Molecular cytogenetic data suggest that the Xp22.3 inversion breakpoint is located in intron 1 of ARHGAP6, the gene encoding the Rho GTPase activating protein 6. Future molecular studies in karyotypically normal female MLS patients to detect submicroscopic rearrangements including the ARHGAP6 gene as well as mutation screening of ARHGAP6 in patients with no obvious chromosomal rearrangements will clarify the role of this gene in MLS syndrome.

Unexpected death of a 12 year old boy with monosomy 1p36

Monosomy 1p36 may result in a clinically recognizable chromosomal microdeletion syndrome. We report the unexpected death of a 12 year old boy with mildly dysmorphic facial features, short stature at 138 cm (3rd centile), moderate mental retardation and a history of seizures, obesity, transient muscle weakness of the right arm and leg and episodes of transient atonic hemiparesis of the right side of the body. Despite the relatively few congenital anomalies and normal karyotype, the 1p36 deletion was suspected on clinical grounds and was demonstrated by fluorescent in situ hybridisation (FISH). Two months after diagnosis and following a short history of a mild upper airway infection, high fever and severe diarrhea, the patient had a massive circulatory shock and asystolia, resulting in deep coma, brain edema, apallic syndrome and death. To our knowledge there has been no previous report of episodes of transient unilateral muscle weakness and atonic hemiparesis, circulatory shock and sudden death associated with monosomy 1p36.

[DiGeorge syndrome/velcardiofacial syndrome: oral and maxillofacial surgery]

The DiGeorge syndrome/velocardiofacial syndrome is the most frequent chromosomal microdeletion syndrome. Partial deletion of chromosome 22q11 may lead to symptoms including facial dysmorphy, hypoparathyroidism, thymic aplasia, congenital heart disease, developmental retardation, and disturbance of speech development. According to the literature, 9% of patients have cleft palate, an additional 5% have a submucosal cleft, and a total of 32% show velopharyngeal insufficiency. We studied 64 children with a cleft, or with delayed speech development and a submucosal or occult cleft, for the presence of the 22q11deletion using fluorescent in situ hybridisation. Five patients had the 22q11 deletion. We conclude that patients presenting with nasal speech and additional anomalies should all be studied for the presence of submucosal or occult clefting and for the presence of the DiGeorge syndrome/velocardiofacial syndrome.

Sudden death of a girl with Prader-Willi syndrome

We report on the sudden death of a 3.5-year-old girl with Prader-Willi syndrome (PWS) and 15q11-q13 deletion. She suffered from severe chronic breathing disturbances and recurrent bronchitis. During an episode of acute bronchitis she had a cardiac arrest and died two months later of the sequelae. Brain CT imaging three weeks after the arrest showed bilateral symmetrical haemorrhages in the basal ganglia region. The spatial distribution of the haemorrhages can possibly suggest that the basal ganglia in PWS may be especially susceptible to hypoxemia.

A girl with cutaneous hyperpigmentation, café au lait spots and ring chromosome 15 without significant deletion

Ring chromosome 15 [r(15)] syndrome is characterised by specific facial features, café au lait spots, failure to thrive, mental retardation and typically with a terminal deletion of the long arm of chromosome 15. We report a 2.5 year old girl showing normal growth and development, large hyperpigmented skin changes showing hypopigmentated areas inside, multiple café au lait spots and premature graying-like hypopigmentation of scalp hair. She had a karyotype of r(15) in peripheral lymphocytes and fibroblasts. By FISH analysis the breakpoint was located distal to locus D15S936 (15q26.3) and within 300 kb of the end of the chromosome, indicating no deletion of functional genes on 15q. Hyperpigmentation and café au lait spots are rare signs in ring chromosome syndromes, but with r(15) syndrome, café au lait spots have been described in about 30% of patients and have been considered to result from the deletion of gene(s) on distal 15q. Based on the frequent observation of patchy hyperpigmentation with the r(15) syndrome, absent hyperpigmentation in cases of distal 15q deletion without a ring chromosome, and the telomeric breakpoint location in our patient indicating no significant deletion, we propose that the cutaneous hyperpigmentation and café au lait spots in our proband represent effects of the r(15) chromosome but are not caused by the deletion of specific gene(s) on distal 15q. Patchy skin hypopigmentation is a well known nonspecific sign in cytogenetic mosaicism which is commonly seen in ring syndrome.

Characterization of relaxin binding in the uterus of the marmoset monkey

The ovarian peptide hormone relaxin (RLX) plays an important role in the regulation of the endometrium both during the cycle and in early pregnancy. RLX interacts with specific receptors on endometrial stromal cells causing these to decidualize. In order to characterize the molecules with which RLX interacts in the primate uterus, a methodology based on a fully bioactive preparation of biotinylated porcine RLX was applied to cryosections of the uterus of female marmoset monkeys. Specific RLX binding was weakly detected in the proliferative phase in isolated endometrial stromal cells. In the secretory phase, the positively reacting cells increased in staining intensity and in number and also included some epithelial cells. Further increases occurred in pregnancy, but RLX binding in the endometrium decreased at the end of the cycle if pregnancy did not occur. The myometrium showed weak staining which did not vary through the cycle, but increased in pregnancy. Electrophoretic analysis of the RLX-binding moieties in these tissue sections indicated that a protein of approximately 40 kDa was the principal RLX-binding molecule, while minor specific bands were detectable at approximately 100 and approximately 200 kDa. The binding of biotinylated RLX could be specifically suppressed by co-incubation with unlabelled RLX, but not by insulin, IGF-I or biotin. This technique therefore allows the detection and molecular characterization of specific RLX binding in the primate uterus. In the marmoset monkey, the pattern of specific binding closely reflects the RLX-dependent physiology during implantation and early pregnancy, implying the probable involvement of a specific RLX receptor.

Relaxin signalling links tyrosine phosphorylation to phosphodiesterase and adenylyl cyclase activity

The relaxin receptor has so far avoided molecular cloning and characterization. We have therefore characterized the signalling events activated by relaxin (RLX), using two different cell culture-based bioassay systems: primary human endometrial stromal cells from the cycle (ESC) and the human monocyte cell line THP-1. Upon RLX stimulation, both cell types showed a rapid increase in cAMP accumulation, which could be inhibited by an inhibitor of G-protein activation, GDP-beta-S. However, evolutionarily one would expect the RLX receptor, like those for the structurally related hormones insulin and insulin-like growth factor-I, to involve tyrosine kinase activity. The specific tyrphostins AG 1478, AG 527 and AG 879 inhibited the RLX-stimulated cAMP response in human ESC and THP-1 cells in a dose-dependent manner, though the potent broad range tyrphostin AG 213 had no effect. Also, treatment of THP-1 cells with the potent phosphotyrosine phosphatase inhibitors bpV(phen) and mpV(pic) increased RLX-stimulated cAMP accumulation in a dose-dependent manner. The effect of the general tyrosine kinase inhibitor genistein (which can also inhibit some phosphodiesterases) on RLX-mediated cAMP accumulation strongly depended on the activity status of phosphodiesterase. In the absence of a phosphodiesterase inhibitor, genistein enhanced RLX-stimulated cAMP accumulation in both bioassays. When phosphodiesterase was inhibited by isobutylmethylxanthine, this effect was not observed. The results imply that activation of the RLX receptor uses tyrosine kinase signalling to control phosphodiesterase activity, and hence to up-regulate intracellular cAMP.

[Analysis of a case of balanced chromosome translocation and phenotypic abnormality by fluorescence in situ hybridization]

OBJECTIVE

To delineate the chromosome structural aberration in a case of chromosome translocation by fluorescence in situ hybridization(FISH) technique and precisely identify the breakpoints.

METHODS

The whole chromosome point 5(wcp5) and locus- specific probes derived from yeast artificial chromosomes(YACs) mapping the nearby region of breakpoints were used to delineate the translocation t(5;10) found by high resolution G-banding examination in a case with congenital abnormality.

RESULTS

A balanced translocation was confirmed and the breakpoints were located in the 1.5 Mb area on chromosome 5 and within the approximately 3 Mb interval on chromosome 10.

CONCLUSION

The phenotypic abnormality might result from the disruption of disease-associated gene(s) or microrearrangement(s) on the site of breakpoint(s).

Bioactivity of recombinant prorelaxin from the marmoset monkey

The hormone relaxin (RLX) is generally present in the serum of humans and primates as a heterodimer, though some unprocessed prohormone may also be present. In order to test whether this proRLX is biologically relevant for human or primate physiology, recombinant marmoset monkey proRLX was synthesized in a baculovirus-infected cell system and tested in different bioassays. Marmoset proRLX is >70% identical to human H2 proRLX, especially in the so-called receptor-binding region of the B-peptide. The bioassay systems used were (a) cAMP production by human endometrial stromal cells and (b) cAMP production by the human monocyte cell line THP-1. In both bioassay systems recombinant proRLX showed comparable EC(50) values to pure porcine heterodimeric relaxin (porcine relaxin, 1.5-2.0 nM; marmoset prorelaxin 4.0-5.0 nM). Additionally, recombinant marmoset prorelaxin was shown to stimulate steroidogenesis in primary cultures of marmoset ovarian theca cells, though with a lower apparent activity than porcine relaxin. It thus appears that precursor processing of human or primate relaxin is not an essential prerequisite for the acquisition of bioactivity, as it is for the closely related hormone insulin, and that circulating prorelaxin is physiologically relevant.

Girl with phenotypic abnormalities and a de novo, apparently balanced translocation 46,XX,t(5;10)(q35.2q11.2)

We describe a three-year-old girl with a triangular face, epicanthus, midfacial hypoplasia, apparently low-set ears, a small mouth with thin vermilion border, and a small chin, hypermobile joints, developmental delay with insecure gait, dystonic movement disorder, speech defect, and a history of unexplained undernutrition. She has a de novo, apparently balanced translocation t(5;10)(q35.2;q11.2). Using fluorescence in situ hybridization (FISH), we located the breakpoints in the 1.5-Mb area defined by YAC 753f5 (5q35.2) and within the approximately 2-Mb interval between 10cen and YAC 933a3 (10q11.21).

Boy with celiac disease, malformations, and ring chromosome 13 with deletion 13q32-->qter

We describe a 2(1/2)-year-old boy with a ring chromosome 13 with distal deletion of 13q32-->qter and celiac disease.

Penoscrotal inversion, hypospadias, imperforate anus, facial anomalies, and developmental delay: definition of a new clinical syndrome

We describe a 2-month-old boy with penoscrotal inversion, hypospadias, imperforate anus, facial anomalies, developmental retardation, and a subtelomeric deletion of chromosome 13q. His phenotype with anogenital malformations and characteristic facies closely resembled two unrelated patients with minute deletions of chromosome 13q who we reported earlier. In addition, he had unilateral renal agenesis. We propose that these patients represent a clinically recognizable, novel chromosomal microdeletion syndrome. The findings indicate the presence of a major gene(s) on chromosome 13q33.2qter that regulate(s) the migration and development of ano-reno-genital cells and organs. We speculate that mutations of this developmental gene(s) may also result in more frequent congenital malformations (isolated hypospadias, uterus bicornis, unilateral renal agenesis). Additional studies are needed to further delineate the genetic defect.

FISH studies in 45 patients with Rubinstein-Taybi syndrome: deletions associated with polysplenia, hypoplastic left heart and death in infancy

Rubinstein-Taybi syndrome (RTS) is a dominant Mendelian disorder characterised by mental retardation, a typical facies, broad thumbs and short stature. Previous reports indicated that 4-25% of RTS patients have a submicroscopic 16p13.3 deletion of the CBP gene. Using FISH and cosmid probes RT100, RT191 and RT203 we studied 45 RTS patients from Germany, the Czech Republic, Austria and Turkey and found four deletions (8.9%, pooled data including other studies: 11%). All deletions were interstitial; three spanned the CBP gene (RT100-RT203) and one was smaller (RT100 only). Previous studies reported no phenotype-genotype correlation between RTS patients with or without a deletion. Our findings suggest a more severe phenotype. The mean age at presentation was 0.96 years in patients with a deletion as against 11.12 years in those without. Patients A and B with a deletion died in infancy which is rare in RTS and was not observed among the other patients. Patients A and D had accessory spleens, Patient A with hypoplastic left heart, abnormal pulmonary lobulation and renal agenesis. This is the second report of hypoplastic left heart and the first report of polysplenia with RTS. The signs suggest a developmental field defect (disturbance of laterality) either as a newly recognised pattern of RTS, or alternatively a novel contiguous gene syndrome.

The novel contiguous gene syndrome of myotubular myopathy (MTM1), male hypogenitalism and deletion in Xq28:report of the first familial case

Hu et al. (1996) and Laporte et al. (1997) recently proposed a novel contiguous gene syndrome of myotubular myopathy, abnormal male genital development and deletion in Xq28. We studied a family where two male infants, both deceased, had myotubular myopathy and intersexual genitalia. Using FISH we detected in the mother a hemizygous deletion including the myotubularin gene MTM1 and F18 (a gene of yet unknown function). DNA studies with STR-markers (short tandem repeats) within and flanking the deleted segment confirmed the deletion in the family and were used for prenatal diagnosis. Our findings confirm the existence of this novel contiguous gene syndrome and support that the deletion of the F18 gene, or a neighboring gene, may cause ambiguous genitalia or severe hypospadias in males. The mother had low muscle power and marked menstrual irregularities which may indicate that she is a manifesting carrier and that the deletion may include a gene (F18 or other) for gonadal function in females.

Identification of cyclin A/Cdk2 phosphorylation sites in B-Myb

B-myb is a highly conserved member of the myb proto-oncogene family that encodes a ubiquitously expressed 110-kDa sequence-specific DNA-binding protein. Transactivation of Myb-inducible promoters by B-Myb is repressed by a regulatory domain located at the C-terminus of the protein. Cyclin A/Cdk2-mediated phosphorylation apparently releases the negative constraint and triggers B-Myb transactivation potential. Two-dimensional tryptic phosphopeptide analysis indicated that the majority of the sites phosphorylated in vivo are targeted in vitro by cyclin A/Cdk2. Six sites in B-Myb fulfil the requirements for recognition by Cdk2. Using point mutation of the phosphorylation sites to nonphosphorylatable amino acids, we show that five of these sites are targets for Cdk2 in vivo. Mutation of one of these residues (T524) to alanine diminished the ability of B-Myb to promote transcription of a reporter gene, suggesting that phosphorylation of B-Myb at this site is important for the regulation of its activity by cyclin A/Cdk2.

Familial Williams-Beuren syndrome

Williams-Beuren syndrome (WBS) occurs sporadically; however, at least four familial cases of WBS have been described previously. We describe a mother and her son with typical WBS. The diagnosis of WBS in the son was confirmed by molecular cytogenetic analysis fluorescence in situ hybridization. He had a deletion of 7q11.23 at the ELN locus. The mother was diagnosed after the identification of WBS in her affected son. She is deceased and was thus not studied by FISH. However, her combined symptoms make it very clear that she had WBS. Two traits uncommon in WBS were observed, unilateral renal hypoplasia in the mother and a hemivertebra at L5 in the son.

Deletion mapping by FISH with BACs in patients with partial monosomy 22q13

Patients with deletions in 22q13 are known to have phenotypic features that include normal or accelerated growth, large hands and feet, hypotonia, delayed psychomotor development and mild facial dysmorphism. To date, very few cases have been investigated by detailed molecular genetic analysis. We have analyzed three new patients with terminal deletions in 22q. We compared the cytogenetic observations with molecular data assessed by fluorescence in situ hybridization and an array of characterized bacterial artificial chromosome recombinants. The shortest region of deletion overlap is localized in 22q13.2-qter distal to the marker D22S94, but the telomeric repeat in the deleted chromosome appears to remain intact. When parental alleles were investigated in two of the three patients, the aberrant homolog was found to be of paternal origin in both cases. Although the deleted region still spans >20 cM, molecular analysis of additional patients and screening for new genes might help in elucidating candidate genes connected with the dysmorphisms defined by deletions of 22q13.

A large family with subtelomeric translocation t(18;21)(q23;q22.1) and molecular breakpoint in the Down syndrome critical region

We describe a 17-month-old infant with clinical features of Down syndrome and a normal karyotype by standard chromosomal analysis, her two uncles aged 28 and 30 years, respectively, with reduced intelligence and unusual appearance but not apparent Down syndrome, and a severely retarded 6-year-old girl with dysmorphy and epilepsy from the same family. Cytogenetic studies of patients and normal intervening relatives had been carried out at different institutions with normal results. Fluorescence in situ hybridization using whole chromosome painting and unique-copy probes (cosmids) and high-resolution banding revealed a familial subtelomeric translocation of chromosomes 18 and 21, resulting in partial trisomy 21 in the infant and her two uncles, and partial monosomy 21 in the 6-year-old girl. Cytogenetic breakpoints were located in bands 18q23 and 21q22.1, respectively. The molecular breakpoint on chromosome 21 was located between D21S211 (proximal) and D21S1283 (distal) and thus maps within the Down syndrome critical region.

A small deletion of 16q23.1-->16q24.2 [del(16)(q23.1q24.2).ish del(16)(q23.1q24.2)(D16S395+, D16S348-, P5432+)] in a boy with iris coloboma and minor anomalies

We report on a 5-year-old boy with bilateral coloboma of iris, short stature, moderate developmental delay, and a few minor craniofacial anomalies. High-resolution GTG banding showed a small distal deletion of one chromosome 16 [del(16)(q23.1q24.2)]. Molecular refinement of the deletion breakpoints yielded that the proximal breakpoint at 16q23.1 is located between loci D16S395 (present) and D16S348 (absent). Comparison with previously published cases of deletion 16q demonstrated that the clinical phenotype is not a recognizable 16q- syndrome and different from the two cases of deletions of 16(q22.1 to q24.1) described by Callen et al. [1993]. Evidently, deletion 16(q23.1q24.2) has a milder phenotypic effect than other interstitial and distal 16q deletions.

Phosphorylation and activation of B-Myb by cyclin A-Cdk2

BACKGROUND

Cyclins and their catalytic partners, the cyclin-dependent kinases (Cdks), function as key regulators of the eukaryotic cell cycle. Specific cyclin-Cdk complexes are active at successive stages during the cell cycle and control cell-cycle progression by phosphorylating specific target proteins, most of which have not yet been identified. B-Myb, a conserved member of the Myb oncoprotein family, is a sequence-specific DNA-binding protein expressed in virtually all proliferating mammalian cells. Increasing evidence suggests that B-Myb plays an important role during the late G1 and early S phases of the cell cycle. In this study, we have examined the regulation of B-Myb activity by cyclin-Cdks.

RESULTS

We found that the transcriptional transactivation potential of B-Myb was repressed by a regulatory domain located at the carboxyl terminus of the protein. Coexpression of B-Myb and cyclin A relieved this repression by phosphorylation of B-Myb in its carboxy-terminal region. Tryptic phosphopeptide mapping revealed that endogenous B-Myb was phosphorylated in cells undergoing S phase.

CONCLUSIONS

This work provides evidence for a link between the Myb oncoprotein family and the cell-cycle machinery. We have shown that the carboxyl terminus of B-Myb acts as a cell-cycle sensor that regulates the transactivation function of B-Myb. Moreover, our studies have identified B-Myb as a target of cyclin A-Cdk2 and have indicated that B-Myb activity is regulated by phosphorylation mediated by cyclin A-Cdk2.

Evidence for a critical region for penoscrotal inversion, hypospadias, and imperforate anus within chromosomal region 13q32.2q34

Two unrelated patients with small distal deletions of the long arm of chromosome 13 are described, with shawl scrotum and penoscrotal transposition, penoscrotal hypospadias, a reduced perineum, and anal atresia. The patients have small deletions of 13(q32.2qter) and 13(q32q34), respectively. This report and the literature present evidence for one or possibly more gene(s) within region 13q32.2q34 which regulate the development of the ano-genital structures. The clinical spectrum includes bifid or shawl scrotum, hypospadias, biseptate uterus, malplaced and imperforate anus, and common cloaca.

Delineation of a contiguous gene syndrome with multiple exostoses, enlarged parietal foramina, craniofacial dysostosis, and mental retardation, caused by deletions in the short arm of chromosome 11

A contiguous gene syndrome due to deletions of the proximal short arm of chromosome 11 is described in eight patients belonging to four families. The main clinical features are multiple exostoses, enlarged parietal foramina, craniofacial dysostosis, and mental retardation. The patients have cytogenetic and/or molecular deletions of chromosome 11p11-p13. These deletions are located between the centromere and D11S914 in a region of approximately 20cM. The present study confirms the presence of a multiple exostoses gene on chromosome 11p. Furthermore, it suggests that the gene for isolated foramina parietalie permagna and genes associated with craniofacial dysostosis and mental retardation reside in the same chromosomal region.

Derivative (6)t(1;6)(q22;p21) revealed in bone marrow cells by FISH 9 months before diagnosis of acute T-lymphoblastic leukemia

A chromosomal clone with unbalanced translocation resulting in partial trisomy of segment 1q22-qter and partial monosomy of segment 6p21-pter was revealed by fluorescence in situ hybridization (FISH) using a panel of different whole chromosome painting probes. The pathologic clone appeared after sequential chemotherapy treatment for AML-M5 when the patient was in complete remission before development of T-ALL. However, this clone was present during the whole period of treatment for T-ALL. The clone remained the only chromosomal aberration found. Breakpoints were detected more easily and more precisely with the use of the FISH technique than with G-banding only.

DNA, FISH and complementation studies in ICF syndrome: DNA hypomethylation of repetitive and single copy loci and evidence for a trans acting factor

ICF syndrome (ICFS) is a rare immunodeficiency disorder characterized by instability of the pericentromeric heterochromatin predominantly of chromosomes 1 and 16. DNA methylation studies in two unrelated ICFS patients provide further evidence for a marked hypomethylation of satellite 2 DNA. The ICFS-specific disturbances of chromatin structure take place within the satellite 2 DNA regions, as demonstrated by fluorescence in situ hybridization analysis. Moreover, methylation studies of genomic imprinted loci D15S63, D15S9, and H19 have revealed hypomethylation to different degrees in both patients; this provides evidence for hypomethylation at autosomal single copy loci in ICFS. Cell fusion experiments have revealed a distinct reduction of chromosomal abnormalities in ICFS cells after fusion with normal cells, suggesting that the abnormalities are caused by the loss of function of an as yet unknown trans acting factor. Although it is now clear that wide-spread DNA hypomethylation is a characteristic feature of ICFS, neither the cause and mechanism of hypomethylation nor their relationship to the clinical symptoms is known. We speculate that a phenotypic effect might result from tissue-dependent abnormal gene expression and/or from a possible structural disturbance of DNA domains, which, with respect to the immunodeficiency, partially prevents the normal somatic recombinations in immunologically active cells.

Fryns syndrome: two further cases without lateral diaphragmatic defects

We report on two unrelated infants with Fryns syndrome but without lateral diaphragmatic defects. In case 1, a female stillborn, pertinent findings included a coarse facies, cleft palate, short neck with a broad pterygium, heart defect, lung hypoplasia, omphalocele, urogenital malformations, anal atresia, and distal digital hypoplasia. Case 2 showed a coarse facies with cleft lip and palate, para-oesophageal hernia with herniation of the stomach into the thoracic cavity, malrotation of the intestine, hydronephrosis, and anal atresia. At age 14 months she was developmentally severely retarded. These observations represent the 11th and 12th reports of probable Fryns syndrome without lateral diaphragmatic defect.

Mulvihill-Smith syndrome: case report and review

We report a 20 year old man with short stature, microcephaly, unusual facies, numerous pigmented naevi, hypodontia, immunodeficiency, and a high pitched voice. Tympner et al had assumed that the patient had a new syndrome of "progressive combined immunodeficiency and ectomesodermal dysplasia". We show here that the condition is identical to the Mulvihill-Smith syndrome (McKusick 176690), a progeroid disorder described in four or possibly five sporadic cases to date. We describe his clinical progress up to the age of 20 years. Our patient suffered from severe viral infections, allergic rhinitis and conjunctivitis, delayed puberty, visual loss, modest achievement in high school, and reactive depression. The immunological, facioskeletal, and dental abnormalities are presented in detail.