Irina N. Bespalova

A gene for autosomal dominant hearing impairment (DFNA14) maps to a region on chromosome 4p16.3 that does not overlap the DFNA6 locus

Non-syndromic hearing impairment is one of the most heterogeneous hereditary conditions, with more than 40 reported gene localisations. We have identified a large Dutch family with autosomal dominant non-syndromic sensorineural hearing impairment. In most patients, the onset of hearing impairment is in the first or second decade of life, with a slow decline in the following decades, which stops short of profound deafness. The hearing loss is bilateral, symmetrical, and only affects low and mid frequencies up to 2000 Hz. In view of the phenotypic similarities of this family with an American family that has been linked to chromosome 4p16.3 (DFNA6), we investigated linkage to the DFNA6 region. Lod score calculations confirmed linkage to this region with two point lod scores above 6. However, as haplotype analysis indicated that the genetic defect in this family is located in a 5.6 cM candidate region that does not overlap the DFNA6 region, the new locus has been named DFNA14.

Effects of vagus nerve stimulation on progressive myoclonus epilepsy of Unverricht-Lundborg type.

Summary: Purpose: A 34‐year‐old woman with progressive myoclonus epilepsy of Unverricht‐Lundborg type was considered for vagus nerve stimulation (VNS) therapy.

Pathogenesis of clinical signs in recessive ataxia with saccadic intrusions.

We describe a family of Slovenian descent with progressive ataxia, corticospinal signs, axonal sensorimotor neuropathy, and disruption of visual fixation by saccadic intrusions. Chromosome mapping indicated a mutation on 1p36, and this recessive disorder has been designated spinocerebellar ataxia with saccadic intrusions. Affected patients showed overshooting horizontal saccades, macrosaccadic oscillations, and increased velocity of larger saccades; other eye movements were normal. Slowed conduction in axons that are selectively vulnerable to the molecular defect could explain both the sensorimotor neuropathy and the saccadic disorder, which would be caused by delayed feedback control because of slow conduction in cerebellar parallel fibers.

A Form of Inherited Cerebellar Ataxia with Saccadic Intrusions, Increased Saccadic Speed, Sensory Neuropathy, and Myoclonus

Over the past five years, rapid progress has been made in genetically identifying different forms of spinocerebellar atrophy (SCA), for which several characteristic disorders of eye movements have been reported. 1,2 Nonetheless, the genetic disorder in some families has not yet been discovered, and this report concerns one such kinship. We studied a family of Slovenian descent in which 5 of 14 siblings presented with progressive ataxia. Two other siblings, who we did not study, may also show involvement, but neither parent and none of 27 children of the 14 siblings has been affected. We examined the five definitely affected patients several times over a 5year period; electroencephalography, electromyography, and MRI brain imaging were performed. In Patient 5 (the proband), we carried out genetic screening (Athena Laboratories) for Friedreich’s ataxia, spinocerebellar ataxia (SCA) 1-3 and 6-8, and Unverricht-Lundborg progressive myoclonic epilepsy (EMP1). We compared results of eye movement studies with a group of 10 normal subjects (2 female; median age 40 years, range 23–60). We measured horizontal and vertical eye movements using the magnetic search coil technique. We tested fixation, horizontal and vertical saccades, smooth pursuit, and vestibulo-ocular reflex (VOR), and vergence, as previously described. 3,4 All patients and subjects gave informed, written consent, as approved by our Institutional Review Board. Clinical findings of the five affected sibs that we studied are summarized in TABLE 1. Disease onset was insidious; early symptoms could be remembered by all sibs during their early twenties, consisting of gait unsteadiness and difficulty read

No association between DFNA6 and Pro250Arg mutation in FGFR3

has been found to cosegregate with au-tosomal dominant craniosynostosis and bilateral sen-sorineural hearing loss in a large Australian family[Hollway et al., 1998]. Because the penetrance of thecraniosynostosis was low and its manifestations oftensubtle, it was hypothesized that some families with thePro250Arg mutation could present with deafnessalone. The hearing loss in the reported family re-sembled that of the