Margaret A. Kenna

GJB2 Mutations and Degree of Hearing Loss: A Multicenter Study

Hearing impairment (HI) affects 1 in 650 newborns, which makes it the most common congenital sensory impairment. Despite extraordinary genetic heterogeneity, mutations in one gene, GJB2, which encodes the connexin 26 protein and is involved in inner ear homeostasis, are found in up to 50% of patients with autosomal recessive nonsyndromic hearing loss. Because of the high frequency of GJB2 mutations, mutation analysis of this gene is widely available as a diagnostic test. In this study, we assessed the association between genotype and degree of hearing loss in persons with HI and biallelic GJB2 mutations. We performed cross-sectional analyses of GJB2 genotype and audiometric data from 1,531 persons, from 16 different countries, with autosomal recessive, mild-to-profound nonsyndromic HI. The median age of all participants was 8 years; 90% of persons were within the age range of 0-26 years. Of the 83 different mutations identified, 47 were classified as nontruncating, and 36 as truncating. A total of 153 different genotypes were found, of which 56 were homozygous truncating (T/T), 30 were homozygous nontruncating (NT/NT), and 67 were compound heterozygous truncating/nontruncating (T/NT). The degree of HI associated with biallelic truncating mutations was significantly more severe than the HI associated with biallelic nontruncating mutations (P<.0001). The HI of 48 different genotypes was less severe than that of 35delG homozygotes. Several common mutations (M34T, V37I, and L90P) were associated with mild-to-moderate HI (median 25-40 dB). Two genotypes--35delG/R143W (median 105 dB) and 35delG/dela(GJB6-D13S1830) (median 108 dB)--had significantly more-severe HI than that of 35delG homozygotes.

Clinical Practice Guideline: Otitis Media with Effusion

The clinical practice guideline on otitis media with effusion (OME) provides evidence-based recommendations on diagnosing and managing OME in children. This is an update of the 1994 clinical practice guideline “Otitis Media With Effusion in Young Children,” which was developed by the Agency for Healthcare Policy and Research (now the Agency for Healthcare Research and Quality). In contrast to the earlier guideline, which was limited to children aged 1 to 3 years with no craniofacial or neurologic abnormalities or sensory deficits, the updated guideline applies to children aged 2 months through 12 years with or without developmental disabilities or underlying conditions that predispose to OME and its sequelae. The American Academy of Pediatrics, American Academy of Family Physicians, and American Academy of Otolaryngology- Head and Neck Surgery selected a subcommittee composed of experts in the fields of primary care, otolaryngology, infectious diseases, epidemiology, hearing, speech and language, and advanced practice nursing to revise the OME guideline. The subcommittee made a strong recommendation that clinicians use pneumatic otoscopy as the primary diagnostic method and distinguish OME from acute otitis media (AOM). The subcommittee made recommendations that clinicians should (1) document the laterality, duration of effusion, and presence and severity of associated symptoms at each assessment of the child with OME; (2) distinguish the child with OME who is at risk for speech, language, or learning problems from other children with OME and more promptly evaluate hearing, speech, language, and need for intervention in children at risk; and (3) manage the child with OME who is not at risk with watchful waiting for 3 months from the date of effusion onset (if known), or from the date of diagnosis (if onset is unknown). The subcommittee also made recommendations that (4) hearing testing be conducted when OME persists for 3 months or longer, or at any time that language delay, learning problems, or a significant hearing loss is suspected in a child with OME; (5) children with persistent OME who are not at risk should be reexamined at 3- to 6-month intervals until the effusion is no longer present, significant hearing loss is identified, or structural abnormalities of the eardrum or middle ear are suspected; and (6) when a child becomes a surgical candidate, tympanostomy tube insertion is the preferred initial procedure. Adenoidectomy should not be performed unless a distinct indication exists (nasal obstruction, chronic adenoiditis); repeat surgery consists of adenoidectomy plus myringotomy, with or without tube insertion. Tonsillectomy alone or myringotomy alone should not be used to treat OME. The subcommittee made negative recommendations that (1) population-based screening programs for OME not be performed in healthy, asymptomatic children and (2) antihistamines and decongestants are ineffective for OME and should not be used for treatment; antimicrobials and corticosteroids do not have long-term efficacy and should not be used for routine management. The subcommittee gave as options that (1) tympanometry can be used to confirm the diagnosis of OME and (2) when children with OME are referred by the primary clinician for evaluation by an otolaryngologist, audiologist, or speech-language pathologist, the referring clinician should document the effusion duration and specific reason for referral (evaluation, surgery), and provide additional relevant information such as history of AOM and developmental status of the child. The subcommittee made no recommendations for (1) complementary and alternative medicine as a treatment for OME based on a lack of scientific evidence documenting efficacy and (2) allergy management as a treatment for OME based on insufficient evidence of therapeutic efficacy or a causal relationship between allergy and OME. Last, the panel compiled a list of research needs based on limitations of the evidence reviewed. The purpose of this guideline is to inform clinicians of evidence-based methods to identify, monitor, and manage OME in children aged 2 months through 12 years. The guideline may not apply to children older than 12 years because OME is uncommon and the natural history is likely to differ from younger children who experience rapid developmental change. The target population includes children with or without developmental disabilities or underlying conditions that predispose to OME and its sequelae. The guideline is intended for use by providers of health care to children, including primary care and specialist physicians, nurses and nurse practitioners, physician assistants, audiologists, speech-language pathologists, and child development specialists. The guideline is applicable to any setting in which children with OME would be identified, monitored, or managed. This guideline is not intended as a sole source of guidance in evaluating children with OME. Rather, it is designed to assist primary care and other clinicians by providing an evidence-based framework for decision-making strategies. It is not intended to replace clinical judgment or establish a protocol for all children with this condition, and may not provide the only appropriate approach to diagnosing and managing this problem. (Otolaryngol Head Neck Surg 2004;130:S95.)

Airway foreign bodies (FB): a 10-year review

A retrospective chart review of children who had airway foreign body removed via direct laryngoscopy and bronchoscopy (DLB) from 1987-1997 was conducted in Childrens Hospital, Boston. Patient characteristics noted included age, sex, and clinical presentation. Pre-operative radiographic findings, reason for delay in evaluation, DLB findings, length of procedure, reason for repeat DLB, and types of foreign body etc. were recorded. Serious complications from aspirated foreign bodies such as severe airway obstruction and death tend to occur in infants and younger children because of their small airway size. A history compatible with foreign body aspiration dictates diagnostic endoscopy with or without radiologic confirmation. Chest and airway radiographs supplemented by fluoroscopy can increase the ratio of correct and early diagnosis. Fluoroscopy should be universally accepted as an initial diagnostic technique in airway foreign body evaluation. Fluoroscopy is not a worthwhile investigation if a preceeding chest radiograph suggests the presence of a foreign body. Long-standing airway foreign bodies are associated with considerable morbidity, and early diagnosis remains the key to successful and uncomplicated management of foreign body aspiration. Education aimed at increasing diagnostic acumen of the physicians and heightening of public awareness are the most important steps needed to reduce the morbidity and mortality. Parents should be instructed to abstain from feeding nuts and seeds to young children and to keep small, potentially ingestible objects out of their reach.

A multicenter study of the frequency and distribution of GJB2 and GJB6 mutations in a large North American cohort

Purpose: The aim of the study was to determine the actual GJB2 and GJB6 mutation frequencies in North America after several years of generalized testing for autosomal recessive nonsyndromic sensorineural hearing loss to help guide diagnostic testing algorithms, especially in light of molecular diagnostic follow-up to universal newborn hearing screening.Methods: Mutation types, frequencies, ethnic distributions, and genotype-phenotype correlations for GJB2 and GJB6 were assessed in a very large North American cohort.Results: GJB2 variants were identified in 1796 (24.3%) of the 7401 individuals examined, with 399 (5.4%) homozygous and 429 (5.8%) compound heterozygous. GJB6 deletion testing was performed in 12.0% (888/7401) of all cases. The >300-kb deletion was identified in only nine individuals (1.0%), all of whom were compound heterozygous for mutations in GJB2 and GJB6. Among a total of 139 GJB2 variants identified, 53 (38.1%) were previously unreported, presumably representing novel pathogenic or benign variants.Conclusions: The frequency and distribution of sequence changes in GJB2 and GJB6 in North America differ from those previously reported, suggesting a considerable role for loci other than GJB2 and GJB6 in the etiology of autosomal recessive nonsyndromic sensorineural hearing loss, with minimal prevalence of the GJB6 deletion.Purpose: To determine short–term effects of intravitreal bevacizumab for subfoveal choroidal neovascularization (CNV) in pathologic myopia. Methods: In this prospective interventional case series, patients were treated with 2.5 mg of intravitreal bevacizumab and followed for 3 months. Best-corrected visual acuity (BCVA), optical coherence tomography (OCT), and fluorescein angiography (FA) were recorded. Indications for retreatment were active leaking CNV shown by FA and presence of subretinal fluid by OCT in combination with visual disturbances. Results: Fourteen patients were included, with a mean age of 53.86 ± 16.26 years (range 29–85). Mean spherical equivalent was −13.87 ± 3.68 diopters (−7.25 to −20.50). Minimum follow-up was 3 months. There were no adverse events. The mean initial visual acuity was 20/200 improving to 20/100 at 2 weeks, 20/80 at 4 weeks, and 20/60 at 8 and 12 weeks (P = 0.007; P = 0.001; P = 0.005; P = 0.001, respectively). Initial foveal thickness improved from 385.43 &mgr;m ± 125.83 &mgr;m to 257.64 ± 76.6 &mgr;m and 194.54 ± 54.35 &mgr;m after the first and third month, respectively (P = 0.001). Conclusions: Initial treatment results of patients with CNV due to pathologic myopia did not reveal any short-term safety concerns. Intravitreal bevacizumab resulted in a significant decrease in foveal thickness and improvement in visual acuity. These favorable initial results support further larger and long-term studies.

Mechanical Link between Cohesion Establishment and DNA Replication: Ctf7p/Eco1p, a Cohesion Establishment Factor, Associates with Three Different Replication Factor C Complexes

ABSTRACT CTF7/ECO1 is an essential yeast gene required for the establishment of sister chromatid cohesion. The findings that CTF7/ECO1, POL30 (PCNA), and CHL12/CTF18 (a replication factor C [RFC] homolog) genetically interact provided the first evidence that the processes of cohesion establishment and DNA replication are intimately coupled—a link now confirmed by other studies. To date, however, it is unknown how Ctf7p/Eco1p function is coupled to DNA replication or whether Ctf7p/Eco1p physically associates with any components of the DNA replication machinery. Here, we report that Ctf7p/Eco1p associates with proteins that perform partially redundant functions in DNA replication. Chl12p/Ctf18p combines with Rfc2p to Rfc5p to form one of three independent RFC complexes. By chromatographic methods, Ctf7p/Eco1p was found to associate with Chl12/Ctf18p and with Rfc2p, Rfc3p, Rfc4p, and Rfc5p. The association between Ctf7p/Eco1p and this RFC complex is biologically relevant in that (i) Ctf7p/Eco1p cosediments with Chl12p/Ctf18p in vivo and (ii) rfc5-1 mutant cells exhibit precocious sister separation. Previous studies revealed that Rfc1p or Rad24p associates with Rfc2p to Rfc5p to form two other RFC complexes independent of Ctf18p-RFC complexes. These Rfc1p-RFC and Rad24p-RFC complexes function in DNA replication or repair and DNA damage checkpoint pathways. Importantly, Ctf7p/Eco1p also associates with Rfc1p and Rad24p, suggesting that these RFC complexes also play critical roles in cohesion establishment. The associations between Ctf7p/Eco1p and RFC subunits provide novel evidence regarding the physical linkage between cohesion establishment and DNA replication. Furthermore, the association of Ctf7p/Eco1p with each of three RFC complexes supplies new insights into the functional redundancy of RFC complexes in cohesion establishment.

Medical management of chronic suppurative otitis media without cholesteatoma in children

Tympanomastoid surgery is considered standard management for chronic suppurative otitis media (CSOM) without cholesteatoma, which is unresponsive to ototopical/oral antimicrobial therapy. The following makes this sequence of management less attractive today: 1. potential ototoxicity of ototopical agents; 2. lack of oral antimicrobial agents effective against most common pathogens (e.g., Pseudomonas aeruginosa); 3. frequent occurrence in children who have tympanostomy tubes; and 4. failure of tympanomastoid surgery to eradicate the disease in all cases. We conducted a study in 36 pediatric patients with chronic suppurative otitis media, in which all received parenteral antimicrobial therapy and daily aural toilet (mean duration of treatment = 9.7 days). Thirty‐two patients (89%) had resolution of their infection with medical therapy alone; four children required tympanomastoidectomy. Further investigation is needed to understand the etiology, pathogenesis, and most effective methods of management/prevention of CSOM in children.

Invading the Yeast Nucleus: a Nuclear Localization Signal at the C Terminus of Ty1 Integrase Is Required for Transposition In Vivo

ABSTRACT Retrotransposon Ty1 faces a formidable cell barrier during transposition—the yeast nuclear membrane which remains intact throughout the cell cycle. We investigated the mechanism by which transposition intermediates are transported from the cytoplasm (the presumed site of Ty1 DNA synthesis) to the nucleus, where they are integrated into the genome. Ty1 integrase has a nuclear localization signal (NLS) at its C terminus. Both full-length integrase and a C-terminal fragment localize to the nucleus. C-terminal deletion mutants in Ty1 integrase were used to map the putative NLS to the last 74 amino acid residues of integrase. Mutations in basic segments within this region decreased retrotransposition at least 50-fold in vivo. Furthermore, these mutant integrase proteins failed to localize to the nucleus. Production of virus-like particles, reverse transcriptase activity, and complete in vitro Ty1 integration resembled wild-type levels, consistent with failure of the mutant integrases to enter the nucleus.

Acupressure-Acupuncture Antiemetic Prophylaxis in Children Undergoing Tonsillectomy

BACKGROUND Acupuncture or acupressure at the Nei-Guan (P.6) point on the wrist produces antiemetic effects in awake but not anesthetized patients. The authors studied whether a combined approach using preoperative acupressure and intra- and postoperative acupuncture can prevent emesis following tonsillectomy in children. METHODS Patients 2-12 yr of age were randomly assigned to study or placebo groups. Two Acubands with (study) and two without (placebo) spherical beads were applied bilaterally on the P.6 points; non-bead- and bead-containing Acubands, respectively, were applied on the sham points. All Acubands were applied before any drug administration. After anesthetic induction, acupuncture needles were substituted for the beads and remained in situ until the next day. All points were covered with opaque tape to prevent study group identification. A uniform anesthetic technique was used; postoperative pain was managed initially with morphine and later with acetaminophen and codeine. Emesis, defined as retching or vomiting, was assessed postoperatively. Ondansetron was administered only after two emetic episodes at least 2 min apart. Droperidol was added if emesis persisted. RESULTS One hundred patients were enrolled in the study. There were no differences in age, weight, follow-up duration, or perioperative opioid administration between groups. Retching occurred in 26% of the study patients and in 28% of the placebo patients; 51 and 55%, respectively, vomited; and 60 and 59%, respectively, did either. There were no significant differences between the groups. Redness occurred in 8.5% of acupuncture sites. CONCLUSION Perioperative acupressure and acupuncture did not diminish emesis in children following tonsillectomy.

Effect of Adenotonsillectomy in PFAPA Syndrome

OBJECTIVE To assess the benefits of adenotonsillectomy in the treatment of pediatric patients with PFAPA (periodic fever, aphthous ulcers, pharyngitis, and adenitis) syndrome. DESIGN Prospective case series. SETTING Tertiary care pediatric hospital. PATIENTS Pediatric patients meeting criteria for PFAPA syndrome. INTERVENTION Tonsillectomy with or without adenoidectomy. MAIN OUTCOME MEASURE Resolution of PFAPA symptoms. RESULTS Twenty-seven (14 female, 13 male) children with PFAPA syndrome underwent tonsillectomy with or without adenoidectomy from 2004 through 2006. The length of follow-up for all patients ranged from 8 to 41 months. A total of 26 patients experienced a complete resolution of their symptoms. The 1 child who continued to have febrile episodes had fever cycles that were not regular in duration or interval and in hindsight was not likely a patient with PFAPA syndrome. CONCLUSIONS Our findings showed complete resolution of symptoms in 26 of 27 patients with PFAPA syndrome treated surgically. Patients who meet clinical criteria for PFAPA syndrome should be considered for tonsillectomy and adenoidectomy if they do not respond to medical management.

Effectiveness of sequencing connexin 26 (GJB2) in cases of familial or sporadic childhood deafness referred for molecular diagnostic testing

Purpose: Hearing loss is a common congenital disorder that is frequently associated with mutations in the GJB2 gene encoding the connexin 26 protein (Cx26). We sought to evaluate the effectiveness of direct DNA sequencing for detection of Cx26 mutations as a clinical diagnostic test.Methods: We designed a clinical assay using a three-step polymerase chain reaction (PCR)-based DNA sequencing strategy to detect all possible mutations in the open reading frame and flanking sequences of Cx26. The results of the first 324 cases of childhood deafness referred for diagnostic testing were analyzed.Results: A total of 127 of the 324 (39.2%) cases had at least one mutant Cx26 allele (36.1% of sporadic cases, 70% of familial cases). Of these 127 case, 57 (44.8%) were homozygotes or compound heterozygotes. Thirty-four different mutations were identified, including 10 novel mutations, 6 of which (T8M, K15T, R32L, M93I, N206S, and 511-512insAACG) may be pathogenic. We also provide new evidence on the pathogenicity or nonpathogenicity of 12 previously reported mutations, and clarify the confusing nomenclature of the 313-326del14 mutation.Conclusion: A simple and rigorous method for efficient PCR-based sequence analysis of Cx26 is a sensitive clinical assay for evaluating deaf children. Its widespread use is likely to identify additional pathogenic mutations and lead to a better understanding of the clinical significance of previously identified mutations.