Structure of the X-linked Kallmann syndrome gene and its homologous pseudogene on the Y chromosome.

The gene for the X-linked Kallmann syndrome (KAL), a developmental disorder characterized by hypogonadotropic hypogonadism and anosmia, maps to Xp22.3 and has a homologous locus, KALP, on Yq11. We show here that KAL consists of 14 exons spanning 120-200 kilobases that correlate with the distribution of domains in the predicted protein including four fibronectin type III repeats. The KALP locus reveals several large deletions and a number of small insertions, deletions and base substitutions which indicate it is a non-processed pseudogene. The sequence divergence between KAL and KALP in humans, and the chromosomal location of KAL homologous sequences in other primates, suggest that KALP and the steroid sulphatase pseudogene on Yq11 were involved in the same rearrangement event on the Y chromosome during primate evolution.

A mutation in OTOF, encoding otoferlin, a FER-1-like protein, causes DFNB9, a nonsyndromic form of deafness.

Using a candidate gene approach, we identified a novel human gene, OTOF, underlying an autosomal recessive, nonsyndromic prelingual deafness, DFNB9. The same nonsense mutation was detected in four unrelated affected families of Lebanese origin. OTOF is the second member of a mammalian gene family related to Caenorhabditis elegans fer-1. It encodes a predicted cytosolic protein (of 1,230 aa) with three C2 domains and a single carboxy-terminal transmembrane domain. The sequence homologies and predicted structure of otoferlin, the protein encoded by OTOF, suggest its involvement in vesicle membrane fusion. In the inner ear, the expression of the orthologous mouse gene, mainly in the sensory hair cells, indicates that such a role could apply to synaptic vesicles.

Targeted disruption of otog results in deafness and severe imbalance.

Genes specifically expressed in the inner ear are candidates to underlie hereditary nonsyndromic deafness. The gene Otog has been isolated from a mouse subtractive cDNA cochlear library. It encodes otogelin, an N-glycosylated protein that is present in the acellular membranes covering the six sensory epithelial patches of the inner ear: in the cochlea (the auditory sensory organ), the tectorial membrane (TM) over the organ of Corti; and in the vestibule (the balance sensory organ), the otoconial membranes over the utricular and saccular maculae as well as the cupulae over the cristae ampullares of the three semi-circular canals. These membranes are involved in the mechanotransduction process. Their movement, which is induced by sound in the cochlea or acceleration in the vestibule, results in the deflection of the stereocilia bundle at the apex of the sensory hair cells, which in turn opens the mechanotransduction channels located at the tip of the stereo-cilia. We sought to elucidate the role of otogelin in the auditory and vestibular functions by generating mice with a targeted disruption of Otog. In Otog-/- mice, both the vestibular and the auditory functions were impaired. Histological analysis of these mutants demonstrated that in the vestibule, otogelin is required for the anchoring of the otoconial membranes and cupulae to the neuroepithelia. In the cochlea, ultrastructural analysis of the TM indicated that otogelin is involved in the organization of its fibrillar network. Otogelin is likely to have a role in the resistance of this membrane to sound stimulation. These results support OTOG as a possible candidate gene for a human nonsyndromic form of deafness.

[Same-eye comparison of pupillary dilation with an intraoperative standardized intracameral combination of mydriatics (Mydrane®) versus a preoperative ophthalmic (Mydriasert®) in standard cataract surgery in non-diabetic patients (French translation of the article)]. / Comparaison intra-individuelle de la dilatation pupillaire par une solution intracamérulaire standardisée combinée de mydriatiques (Mydrane®) en peropératoire versus un insert ophtalmique (Mydriasert®) en préopératoire dans la chirurgie de la cataracte standard de patients non diabétiques.

INTRODUCTION: Cataract surgery is the most commonly performed surgery in the world, and its success depends in part on the quality of mydriasis. PURPOSE: To compare, for the same eye, the pupillary dilation obtained with Mydrane® (standardized intracameral solution of 0.02% tropicamide, combined with 0.31% phenylephrine and 1% lidocaine) intraoperatively versus Mydriasert® (0.28mg tropicamide insert and 5.4mg phenylephrine) with a contact time between 45 and 60 minutes in the preoperative period. METHODS: Single center prospective study from November 2016 to January 2018 at the Laveran Army Instructional Hospital in Marseille. Patients referred for surgery were dilated at the preoperative consultation with Mydriasert®. The pupillary diameter after 45-60 minutes of contact with the insert was manually measured, by two different examiners, through the "iris image" tab of the Pentacam® elevation topography. Patients were dilated on the day of their cataract surgery with 0.2cc of Mydrane® injected in the anterior chamber through a paracentesis. Thirty seconds later, prior to injection of viscoelastic, an eye photograph was taken by screen capture. The pupillary diameter was evaluated by two different examiners with to the Piximeter 5.9 metrology software. The difference in pupil dilation between Mydriasert® and Mydrane® was tested with the paired series Student t-test. RESULTS: In total, 111 eyes of 82 patients were included. Mydriasert® achieved a mean pupillary dilation of 7.21±0.79mm. The mydriasis obtained with Mydrane® averaged 6.35±0.8mm. This difference of 0.86mm was statistically significant (P<0.001) with a confidence interval of 95% [-0.97; -0.74]. CONCLUSION: On average, Mydrane® dilates the pupil less than Mydriasert®. However, the mydriasis obtained with Mydrane® remains comfortable for the performance of the capsulorhexis. It helps save preoperative time and affords additional anesthetic to the cataract surgery. Nevertheless, the use of Mydriasert® is beneficial when extra mydriasis is required.

Same-eye comparison of pupillary dilation with an intraoperative standardized intracameral combination of mydriatics (Mydrane®) versus a preoperative ophthalmic (Mydriasert®) in standard cataract surgery in non-diabetic patients.

INTRODUCTION: Cataract surgery is the most commonly performed surgery in the world, and its success depends in part on the quality of mydriasis. PURPOSE: To compare, for the same eye, the pupillary dilation obtained with Mydrane® (standardized intracameral solution of 0.02% tropicamide, combined with 0.31% phenylephrine and 1% lidocaine) intraoperatively versus Mydriasert® (0.28mg tropicamide insert and 5.4mg phenylephrine) with a contact time between 45 and 60 minutes in the preoperative period. METHODS: Single center prospective study from November 2016 to January 2018 at the Laveran Army Instructional Hospital in Marseille. Patients referred for surgery were dilated at the preoperative consultation with Mydriasert®. The pupillary diameter after 45-60 minutes of contact with the insert was manually measured, by two different examiners, through the "iris image" tab of the Pentacam® elevation topography. Patients were dilated on the day of their cataract surgery with 0.2cc of Mydrane® injected in the anterior chamber through a paracentesis. Thirty seconds later, prior to injection of viscoelastic, an eye photograph was taken by screen capture. The pupillary diameter was evaluated by two different examiners with to the Piximeter 5.9 metrology software. The difference in pupil dilation between Mydriasert® and Mydrane® was tested with the paired series Student t-test. RESULTS: A hundred and eleven eyes of 82 patients were included. Mydriasert® achieved a mean pupillary dilation of 7.21±0.79mm. The mydriasis obtained with Mydrane® averaged 6.35±0.8mm. This difference of 0.86mm was statistically significant (P<0.001) with a confidence interval of 95% [-0.97; -0.74]. CONCLUSION: On average, Mydrane® dilates the pupil less than Mydriasert®. However, the mydriasis obtained with Mydrane® remains comfortable for the performance of the capsulorhexis. It helps save preoperative time and affords additional anesthetic to the cataract surgery. Nevertheless, the use of Mydriasert® is beneficial when extra mydriasis is required.

Isolation of kidney complementary DNAs down-expressed in Wilms' tumor by a subtractive hybridization approach.

We applied a subtractive hybridization approach to isolate genes differentially expressed between mature kidney and Wilms' tumor. We constructed a complementary DNA library from a total mature kidney complementary DNA subtracted by an excess of mRNA from a Wilms' tumor, WAGR4, with a germline deletion of 11p13 and a somatic loss of alleles at 11p15. Six clones presenting a differential pattern of expression, positive with mRNA from the mature kidney and negative with mRNA from the Wilms' tumor WAGR4, were characterized. Among these clones were two as yet unknown expressed sequences (D11S877E and D15S109E) and four sequences from known genes: renal dipeptidase (DPEP1), alpha B-crystallin (CRYA2), uromodulin (UMOD), and plasma glutathione peroxidase (GPX2). The different patterns of expression of these genes in 11 Wilms' tumors, whether or not they are hereditary, reflect the well-documented pathogenetic heterogeneity for Wilms' tumors. We propose that these clones could be helpful for an improved histological characterization of Wilms' tumors.

Nocardia nova sphenoid sinusitis and infratemporal fossa abscess.

INTRODUCTION: Nocardia sinusitis is exceptional, as a Medline search revealed only one published case. The authors report a case of sphenoid sinusitis complicated by infratemporal fossa abscess, which raised several diagnostic problems. CASE REPORT: The patient was referred with temporal headache, subacute trigeminal neuralgia and subsequent infectious syndrome. Computed tomography imaging revealed left sphenoid sinusitis with osteolysis and infratemporal fossa abscess, as well as suspicious lung nodules suggestive of the initial site of infection. Bacteriological specimens obtained by endoscopic sphenoidotomy confirmed the presence of Nocardia nova. A favourable outcome was observed in response to targeted antibiotic therapy. DISCUSSION AND CONCLUSION: Sphenoid sinusitis with infratemporal fossa abscess is an exceptional mode of presentation of nocardiosis, illustrating the polymorphic clinical features of this disease. Bacteriological examination of samples taken directly from the organ concerned, in this case, by sphenoidotomy, is the only formal diagnostic criterion. Antibiotic therapy with intravenous imipenem/amikacin, followed by oral sulfamethoxazole/trimethoprim (Bactrim Forte(®)) for several months, is the key to successful management.

Characterization of the promoter of the human KAL gene, responsible for the X-chromosome-linked Kallmann syndrome.

We report on the first characterization of the human KAL promoter (pKAL), based on the analysis of a 2-kb fragment of the 5' flanking region. As determined by primer extension, transcription of the human KAL gene is initiated at two different sites in the quail embryonic neuroretina QNR/D cell line. The promoter region is G+C rich and contains a CCAAT box, two binding sites for the SP1 transcription factor and two AP2-binding sites, but no TATA box. It also shares a motif with several neural-specific genes. The ability of four deletion mutants to drive transcription of the heterologous chloramphenicol acetyltransferase (CAT)-encoding gene was determined in transfection experiments. The mutant containing the KAL sequence from nt +2 to -435 demonstrated a tissue-specific, although weak, transcriptional activity only in the quail embryonic neuroretina K2 and QNR/D cell lines. Longer constructs did not confer any activity. Therefore, we suggest that this 437-bp segment of pKAL constitutes a neural-specific promoter which could be negatively controlled by upstream sequences.

Isolation and characterization of the gene responsible for the X chromosome-linked Kallmann syndrome.

Kallmann de Morsier Syndrome is defined by the association of an hypogonadism with an anosmia. The hypogonadism is due to a deficiency of GnRH (gonadotropin-releasing hormone). Olfactory bulbs and tracts are underdeveloped in the patients. Embryological studies have indicated that the migration of GnRH neurons and the axonal extension of olfactory neurons, which both originate in the olfactory epithelium during embryogenesis, were impaired in a fetus affected by X-linked Kallmann Syndrome. By a positional cloning strategy, we have isolated the KAL gene, responsible for the X-linked form of the disease. The gene consists of 14 exons. A highly homologous pseudogene on the Y chromosome has been characterized. The KAL gene encodes a putative secreted protein of 680 amino acids, which contains four fibronectin type III repeats and a four disulphide core motif. The former motif is usually associated with adhesion function. The latter has been described in protein with antiprotease activity. We have isolated the chicken KAL homologue and studied its expression by in situ hybridization during late embryonic development. The gene is expressed in various neuronal populations of the central nervous system, including mitral cells of the olfactory bulbs. We suggested that the KAL protein might be involved in late neuronal differentiation.

Spatiotemporal expression of otogelin in the developing and adult mouse inner ear.

Using a PCR-based subtractive method on cDNA from 2-day-old mouse cochlea, we identified a gene encoding otogelin, Otog, an inner ear specific glycoprotein expressed in all acellular structures. Here, we provide evidence that otogelin is detected as early as embryonic day 10 in the otic vesicle. At this stage, otogelin is detected in the epithelial cells which do not overlap with the myosin VIIA-expressing cells, namely the precursors of the hair cells, thus arguing for an early commitment of the two cell populations. Analysis of otogelin spatiotemporal cell distribution allows a molecular tracing for the contribution of the cochlear and vestibular inner ear supporting cells to the formation of the acellular structures. Throughout embryonic and adult life, the expression of the otogelin gene as monitored by LacZ inserted into Otog, and the abundance of the protein are greater in the vestibule than in the cochlea. In adult, otogelin is still produced by the vestibular supporting cells, which argues for a continuous process of otogelin renewal in the otoconial membranes and cupulae. In contrast, in the tectorial membrane, otogelin should be a long-lasting protein since both the otogelin gene and protein were almost undetectable in adult cochlear cells. The data are consistent with the requirement for otogelin in the attachment of the otoconial membranes and cupulae to their corresponding sensory epithelia as revealed in Otog -/- mice.

Otogelin: a glycoprotein specific to the acellular membranes of the inner ear.

Efforts to identify the specific components of the mammalian inner ear have been hampered by the small number of neuroepithelial cells and the variety of supporting cells. To circumvent these difficulties, we used a PCR-based subtractive method on cDNA from 2-day-old mouse cochlea. A cDNA encoding a predicted 2910-amino acid protein related to mucin has been isolated. Several lines of evidence indicate, however, that this protein does not undergo the O-glycosylation characteristic to mucins. As confirmed by immunocytochemistry and biochemical experiments, this protein is specific to the inner ear. Immunohistofluorescence labeling showed that this protein is a component of all the acellular membranes of the inner ear: i.e., the tectorial membrane of the cochlea, the otoconial and accessory membranes of the utricule and saccule, the cupula of the semicircular canals, and a previously undescribed acellular material covering the otoconia of the saccule. The protein has been named otogelin with reference to its localization. A variety of nonsensory cells located underneath these membranes could be identified as synthesizing otogelin. Finally, this study revealed a maturation process of the tectorial membrane, as evidenced by the progressive organization of otogelin labeling into thick and spaced radial fiber-like structures.

Fdp, a new fibrocyte-derived protein related to MIA/CD-RAP, has an in vitro effect on the early differentiation of the inner ear mesenchyme.

During the course of a study aimed at isolating transcripts specifically or preferentially expressed in the inner ear, we identified a novel gene, encoding a fibrocyte-derived protein, that we named Fdp. Fdp is predicted to be a secreted 128-amino acid protein, which is highly homologous to the melanoma-inhibiting activity/cartilage-derived retinoic acid-sensitive protein (MIA/CD-RAP), a cartilage-specific protein also expressed in several tumors. Fdp and MIA/CD-RAP thus define a new family of proteins. Fdp is expressed from embryonic day 10.5 in the mesenchyme surrounding the otic epithelium. During development, these cells progressively aggregate, condense, and differentiate into cartilaginous cells forming the otic capsule, which no longer expresses Fdp, and into fibrocytes surrounding the epithelia, which strongly express Fdp. In order to address the function of Fdp, we developed an in vitro antisense oligonucleotide approach using microdissected periotic mesenchyme micromass cultures, and showed that Fdp antisense oligonucleotide treatment results in a significant reduction in chondrogenesis. Our results demonstrate that Fdp plays a role in the initiation of periotic mesenchyme chondrogenesis. Accordingly, Fdp and its human ortholog FDP, which map to chromosome 2 and band 20p11, respectively, could be candidate genes for forms of deafness associated with malformations of the otic capsule.

Characterization of the chicken and quail homologues of the human gene responsible for the X-linked Kallmann syndrome.

The human KAL gene, responsible for the X-linked Kallmann syndrome, was isolated previously. Southern blot analysis using human cDNA probes detected cross-hybridization with DNA from several organisms, including chicken and quail. The entire coding sequences of chicken and quail KAL cDNAs were determined. A comparison of these cDNAs with the human KAL cDNA reveals an overall identity of 73 and 72%, respectively. This results in 76 and 75% identity at the protein level. The highest conservation was found in the WAP four-disulfide core motif and in two of the four fibronectin type III repeats reported in the human protein. These results further support the hypothesis that the KAL protein is an extracellular matrix component with anti-protease and adhesion functions.

Chromosomal assignment of the uromodulin gene (UMOD) to 16p13.11.

We report the chromosomal assignment on chromosome arm 16p of a cDNA clone isolated through its expression in mature kidney and lack of expression in several Wilms tumors. DNA sequencing and analysis of the pattern of RNA expression in different tissues identified this clone as a uromodulin (Tamm-Horsfall glycoprotein, uromucoid; UMOD) sequence. By hybridizing this clone to somatic cell hybrids carrying different human chromosomes or segments of chromosome 16, the gene for UMOD was localized to 16p13.11.

X chromosome-linked Kallmann syndrome: stop mutations validate the candidate gene.

Kallmann syndrome represents the association of hypogonadotropic hypogonadism with anosmia. This syndrome is from a defect in the embryonic migratory pathway of gonadotropin-releasing hormone synthesizing neurons and olfactory axons. A candidate gene for the X chromosome-linked form of the syndrome was recently isolated by using a positional cloning strategy based on deletion mapping in the Xp22.3 region. With the PCR, two exons of this candidate gene were amplified on the genomic DNAs from 18 unrelated patients affected with the X chromosome-linked Kallmann syndrome. Three different base transitions--all leading to a stop codon--and one single-base deletion responsible for a frameshift were identified. We thus conclude that the candidate gene is the actual KAL gene responsible for the X chromosome-linked Kallmann syndrome. Furthermore, unilateral renal aplasia in two unrelated patients carrying a stop mutation indicates that the KAL gene is itself responsible for this Kallmann syndrome-associated anomaly. The gene is, therefore, also involved in kidney organogenesis. Additional neurologic symptoms in Kallmann patients are also discussed.