Alpha-B crystallin gene (CRYAB) mutation causes dominant congenital posterior polar cataract in humans.

Congenital cataracts are an important cause of bilateral visual impairment in infants. In a four-generation family of English descent, we mapped dominant congenital posterior polar cataract to chromosome 11q22-q22.3. The maximum LOD score, 3.92 at recombination fraction 0, was obtained for marker D11S898, near the gene that encodes crystallin alpha-B protein (CRYAB). By sequencing the coding regions of CRYAB, we found in exon 3 a deletion mutation, 450delA, that is associated with cataract in this family. The mutation resulted in a frameshift in codon 150 and produced an aberrant protein consisting of 184 residues. This is the first report of a mutation, in this gene, resulting in isolated congenital cataract.

Use of commercially available radiation hybrid panels.

Several panels are available for puchase, and this unit provides update information on the use of the three commercially available panels and on the interpretation of mapping results using the Internet. Radiation hybrid panels continue to serve as integral biological reagents in physical mapping projects and positional cloning.

Identification of novel polymorphisms in the beta7 integrin gene: family-based association studies in inflammatory bowel disease.

Linkage studies from five groups worldwide have confirmed the presence of an inflammatory bowel disease susceptibility locus on chromosome 12q. Beta 7 integrin is a strong candidate gene within this region, and is involved in lymphocyte homing to the gut and retention of intra-epithelial lymphocytes. Monoclonal antibodies to beta7 integrin ameliorate colitis in animal models. We obtained genomic sequence for beta7 integrin, and screened all 16 exons and 1.7 kb of 5' promoter region for polymorphisms in 24 individuals. Fourteen single nucleotide polymorphisms were identified in total and, of these, two common (frequency > or =10%) intronic and two amino acid changing polymorphisms were assessed for potential disease associations. Data were available from 102 multiply affected inflammatory bowel disease families (affected sibling pairs) and 362 simplex (one affected proband) families containing 254 ulcerative colitis, 13 indeterminate colitis and 300 Crohn's disease trios (parents + affected child). No significant associations with any disease phenotype were found with the transmission disequilibrium test. Beta 7 integrin is unlikely to be involved in the genetic susceptibility to inflammatory bowel disease, and therefore future studies on chromosome 12 should focus on other positional candidate genes.

Fibroid embolisation: a technique not without significant complications.

Uterine artery embolisation is a new minimally invasive technique used for the treatment of fibroids. Twenty-one women underwent bilateral uterine artery embolisation at our unit, and we assessed the efficacy, morbidity and patient satisfaction with the procedure. Mixed outcomes were found. Reduction in fibroid volume measured by magnetic resonance imaging was impressive, and the majority of women felt their symptoms had improved. One woman achieved a full term pregnancy following the procedure. However, the procedure involved a significant inpatient stay, analgesia requirement, and a slower recovery time than anticipated. One woman died following overwhelming sepsis occurring 10 days after the procedure. Further studies are required to assess the role this technique may play in the management of uterine fibroids.

A study to evaluate serum and urinary hormone levels following short and long term administration of two regimens of progesterone cream in postmenopausal women.

OBJECTIVE: To determine the pharmacokinetics of a progesterone cream following short and long term dermal administration. DESIGN: Single-centre, randomised, multiple-dose, open-label study. SETTING: Reproductive Medicine Trust, London. POPULATION: Twenty-four healthy postmenopausal women aged between 40 and 65 years were recruited through an advertisement in a local newspaper. METHODS: The women were randomly allocated to progesterone cream 40 mg daily or 20 mg, twice daily, for 42 days. MAIN OUTCOME MEASURES: The concentration of progesterone in the serum was measured on days 1 and 42 before the morning dose, and at 2, 4, 6, 12 and 24 hours after the morning dose. Serum follicle stimulating hormone, oestradiol, testosterone and urinary pregnanediol-3-glucuronide were also measured on days 1 and 42. RESULTS: Three subjects dropped out before using the cream and two more dropped out after the first treatment leaving a reportable sample of 19 women. There was a rise in the mean progesterone concentration at each sampling time between days 1 and 42. There was evidence of a rise in pregnanediol-3-glucuronide over the course of the study. There was no change in follicle stimulating hormone, oestradiol or testosterone. There was no difference between the two regimens. CONCLUSIONS: Transdermal progesterone (40 mg) per day for 42 days causes a small increase in serum progesterone concentration, although there is wide variation. Whether such levels are of clinical benefit remains to be seen.

The ancient source of a distinct gene family encoding proteins featuring RING and C(3)H zinc-finger motifs with abundant expression in developing brain and nervous system.

Intronless genes can arise by germline retrotransposition of a cDNA originating as mRNA from an intron-containing source gene. Previously, we described several members of a family of intronless mammalian genes encoding a novel class of zinc-finger proteins, including one that shows imprinted expression and one that escapes X-inactivation. We report here the identification and characterization of the Makorin ring finger protein 1 gene (MKRN1), a highly transcribed, intron-containing source for this family of genes. Phylogenetic analyses clearly indicate that the MKRN1 gene is the ancestral founder of this gene family. We have identified MKRN1 orthologs from human, mouse, wallaby, chicken, fruitfly, and nematode, underscoring the age and conservation of this gene. The MKRN gene family encodes putative ribonucleoproteins with a distinctive array of zinc-finger motifs, including two to four C(3)H zinc-fingers, an unusual Cys/His arrangement that may represent a novel zinc-finger structure, and a highly conserved RING zinc-finger. To date, we have identified nine MKRN family loci distributed throughout the human genome. The human and mouse MKRN1 loci map to a conserved syntenic group near the T-cell receptor beta cluster (TCRB) in chromosome 7q34-q35 and chromosome 6A, respectively. MKRN1 is widely transcribed in mammals, with high levels in murine embryonic nervous system and adult testis. The ancient origin of MKRN1, high degree of conservation, and expression pattern suggest important developmental and functional roles for this gene and its expressed family members.

Inflammatory bowel disease: progress toward a gene.

The pathogenesis of ulcerative colitis (UC) and Crohn's disease (CD) is still unknown, but the importance of genetic susceptibility has been clearly shown by epidemiological data from family and twin studies. Linkage studies have identified two susceptibility loci for inflammatory bowel disease (IBD) on chromosomes 12 and 16. Importantly, these linkages have been replicated by independent investigators, and studies of positional candidates within these regions continue, together with fine mapping strategies. Regions of 'suggestive' linkage on chromosomes 1, 3, 4, 6, 7, 10, 22 and X have also been reported in individual studies. Other important candidate genes investigated include the interleukin-1 receptor antagonist, MUC3 and genes of the human leukocyte antigen (HLA) system. The apparently conflicting data in different studies from around the world may be explained by ethnic differences, case mix and genetic heterogeneity. Replicated class II HLA associations include HLA DRB1*0103 and DR2 (DRB1*1502), involved in UC susceptibility, and HLA DRB1*03 and DR4 as resistance alleles for CD and UC respectively. Animal studies have provided insights from targeted mutations and quantitative trait locus analysis. The goals of continuing research include narrowing the regions of linkages and analysis of candidate genes, and possibly the application of newly developed methods using single nucleotide polymorphisms. Advances in IBD genetics hold the potential to provide knowledge about the disease pathogenesis at the molecular level, with ensuing benefits for clinical practice.

Imprinting of a RING zinc-finger encoding gene in the mouse chromosome region homologous to the Prader-Willi syndrome genetic region.

A novel locus in the human Prader-Willi syndrome (PWS) region encodes the imprinted ZNF127 and antisense ZNF127AS genes. Here, we show that the mouse ZNF127 ortholog, Zfp127, encodes a homologous putative zinc-finger polypeptide, with a RING (C3HC4) and three C3H zinc-finger domains that suggest function as a ribonucleoprotein. By the use of RT-PCR across an in-frame hexamer tandem repeat and RNA from a Mus musculus x M.spretus F1interspecific cross, we show that Zfp127 is expressed only from the paternal allele in brain, heart and kidney. Similarly, Zfp127 is expressed in differentiated cells derived from androgenetic embryonic stem cells and normal embryos but not those from parthogenetic embryonic stem cells. We hypothesize that the gametic imprint may be set, at least in part, by the transcriptional activity of Zfp127 in pre- and post-meiotic male germ cells. Therefore, Zfp127 is a novel imprinted gene that may play a role in the imprinted phenotype of mouse models of PWS.

Polycystic ovaries and premature male pattern baldness are associated with one allele of the steroid metabolism gene CYP17.

Fourteen Caucasian families with 81 affected individuals have been assessed in which polycystic ovaries/male pattern baldness (PCO/MPB) segregates as an autosomal dominant phenotype (1). The gene CYP17, coding for P450c17 alpha (17 alpha-hydroxylase; 17/20 lyase) on chromosome 10q24.3 is the rate-limiting step in androgen biosynthesis. We have identified a new single base change in the 5' promoter region of CYP17 by heteroduplex analysis. This creates an additional SP1-type (CCACC box) promoter site, which may cause increased expression. This base change also creates a recognition site for the restriction enzyme MspA1 allowing a simple screening procedure. There is a significant association between the presence of this base change (A2) and the affected state for consecutively identified Caucasian women with PCO as compared either to consecutively matched controls (P = 0.03) with an odds ratio for those with at least one A2 allele of 3.57, or to a random population (P = 0.02) with an odds ratio of 2.50. Within the fourteen families, members with PCO or MPB have a significant association with the occurrence of at least one A2 allele compared to their normal relatives, with an odds ratio of 2.20 (P = 0.05). The base change does not cosegregate with the affected phenotype within the families showing association, demonstrating that this mutation of CYP17 does not cause PCO/MPB. Variation in the A2 allele of the CYP17 gene is a significant factor modifying the expression of PCO/MPB in families where it has been demonstrated to segregate as a single gene disorder, but it is excluded as the primary genetic defect.

Evidence for a single gene effect causing polycystic ovaries and male pattern baldness.

OBJECTIVE: Polycystic ovary syndrome is one of the most common endocrine disorders but its aetiology remains unknown. It is highly prevalent within families, suggesting a genetic basic for the syndrome, but the mode of inheritance is unclear. The purpose of this study was to determine the mode of inheritance of polycystic ovary syndrome, within the families of affected individuals, by classic segregation analysis. DESIGN: All first degree relatives of affected individuals were screened for the presence or absence of polycystic ovaries in post-menarchal-premenopausal women and early onset male pattern baldness (MPB) in the males. In extended pedigrees, assignment of affected status in post-menopausal women was made by consideration of the clinical history alone. PATIENTS: Fourteen women (probands), presenting with a variety of clinical symptoms, were identified sequentially as having polycystic ovaries (PCO) by ultrasound scan. They were examined in detail to determine their family structure, clinical and endocrine status. Ten families were found to have sufficient members for further study. MEASUREMENTS: All family members had their body mass index calculated, their degree of hirsutism assessed using the Ferriman and Gallwey score and serum levels of gonadotrophins (FSH and LH), testosterone, prolactin and 17 alpha-hydroxyprogesterone measured by radioimmunoassay. A careful reproductive history was taken for each woman and any menstrual disturbance was noted. Obese probands had their glucose and insulin response to a standard 75-g oral glucose tolerance test determined. Each male family member was also assessed for the degree and time of onset of balding. RESULTS: First degree female relatives of affected individuals had a 51% chance of being affected. Early onset male pattern baldness (MPB) was found to be an accurate phenotype for obligate male carriers. Each family showed autosomal dominant inheritance for PCO with greater than 90% penetrance. CONCLUSIONS: We postulate that PCO and male pattern baldness are caused by alleles of the same gene which affect androgen production or action. The different frequencies of PCO and male pattern baldness arise from differing thresholds for phenotypic expression in females and males respectively. The modifying effects of other genes is the most likely explanation of the somewhat variable phenotype.

Low-copy-number repeat sequences flank the DiGeorge/velo-cardio-facial syndrome loci at 22q11.

DiGeorge syndrome and velo-cardio-facial syndrome are associated with deletions within 22q11. In attempting to refine the shortest region of overlap for these syndromes we have employed fluorescence in situ hybridisation. The results obtained for some probes indicate the presence of low-copy-number repeat families dispersed through proximal 22q. Several primate species have been examined for the presence or absence of two sequences mapping to pter-22q11. The results suggest a relatively recent evolutionary origin for these sequences and the loss of one sequence during the course of primate evolution.

Molecular genetic study of the frequency of monosomy 22q11 in DiGeorge syndrome.

It is well established that DiGeorge syndrome (DGS) may be associated with monosomy of 22q11-pter. More recently, DNA probes have been used to detect hemizygosity for this region in patients with no visible karyotypic abnormality. However, DGS has also been described in cases where the cytogenetic abnormality does not involve 22q11; for instance, four cases of 10p- have been reported. In this study we have prospectively analyzed patients, by using DNA markers from 22q11, to assess the frequency of 22q11 rearrangements in DGS. Twenty-one of 22 cases had demonstrable hemizygosity for 22q11. Cytogenetic analysis had identified interstitial deletion in 6 of 16 cases tested; in 6 other cases no karyotype was available. When these results are combined with those from our previous studies, 33 of 35 DGS patients had chromosome 22q11 deletions detectable by DNA probes.

Interstitial deletions in DiGeorge syndrome detected with microclones from 22q11.

DiGeorge syndrome in humans is characterized by immunodeficiency, heart defects, mental retardation and facial dysmorphism; cytogenetic analysis has shown that deletions at 22q11 occur in approximately 25% of cases. To generate DNA markers from this region, we have microdissected and microcloned band q11 of human Chromosome (Chr) 22. Nineteen thousand clones were obtained from material dissected from 20 chromosome fragments. Seventeen of 61 clones analyzed (28%) were repetitive, 27 (44%) gave no signal, and 17 (28%) detected single copy sequences of which ten mapped to Chr 22. Two of these were found to be deleted in patients with DiGeorge syndrome and either monosomy for 22q11-pter or visible interstitial deletions of 22q11. These two markers are also hemizygous in patients with no visible chromosomal abnormality, demonstrating that submicroscopic deletions are common in DiGeorge syndrome patients.

DiGeorge syndrome with isolated aortic coarctation and isolated ventricular septal defect in three sibs with a 22q11 deletion of maternal origin.

DiGeorge syndrome was diagnosed in an infant who had an interrupted aortic arch, hypoparathyroidism, and low T lymphocyte numbers. Two siblings had heart defects that are not commonly described in DiGeorge syndrome (a membranous ventricular septal defect and coarctation of the aorta respectively). These siblings did not have evidence of thymic dysfunction or hypoparathyroidism. Chromosome analysis showed that the mother, whose cardiovascular examination was normal, and her three offspring with heart defects had a 22q11 interstitial deletion, which was confirmed by molecular analysis. This family suggests that 22q11 deletions can cause apparently isolated heart defects and that the range of these defects may be wider than previously recognised. Once the genes that are deleted in this family are characterised they will be useful candidate genes in the investigation of isolated cardiac malformations.

Microdeletions within 22q11 associated with sporadic and familial DiGeorge syndrome.

DiGeorge syndrome (DGS) is a developmental field defect of the third and fourth pharyngeal pouches. It is associated with deletion of 22q11 in 11% of cases. Molecular genetic analysis with probes from 22q11-pter reveals that a subset of markers is hemizygous in DGS patients with normal karyotypes. There is no apparent difference in the phenotype or the severity of the disorder between patients with the smallest detectable submicroscopic deletion and those with the largest cytogenetically visible abnormality. A microdeletion was found in a mildly affected child and in the severely affected child of a mildly affected father. Dysmorphology, especially cardiac outflow tract anomalies, resulting from 22q11 deletion may be more common than currently realized since chromosomes are unlikely to be checked if the complete spectrum of DGS is not present. Antenatal diagnosis, through detection of hemizygosity at 22q11, will be a possibility for mildly affected parents unwilling to risk the birth of a severely affected child.

Localization of 27 DNA markers to the region of human chromosome 22q11-pter deleted in patients with the DiGeorge syndrome and duplicated in the der22 syndrome.

DiGeorge syndrome is a human developmental field defect with the pathological features of an abnormality of embryogenesis at 4 to 6 weeks of gestation. Cytogenetic analyses of patients have revealed a number of instances of monosomy 22q11-pter in this condition. We have analyzed 52 DNA markers that map to 22q11-pter and have found 27 that are deleted in DiGeorge syndrome patients with known monosomy for part of this region and that are duplicated in patients with the der22 syndrome. The set of clones mapping to the DiGeorge region was further assigned to a proximal or a distal location within the deletion.