Canine RPGRIP1 mutation establishes cone–rod dystrophy in miniature longhaired dachshunds as a homologue of human Leber congenital amaurosis

Cone-rod dystrophy 1 (cord1) is a recessive condition that occurs naturally in miniature longhaired dachshunds (MLHDs). We mapped the cord1 locus to a region of canine chromosome CFA15 that is syntenic with a region of human chromosome 14 (HSA14q11.2) containing the retinitis pigmentosa GTPase regulator-interacting protein 1 (RPGRIP1) gene. Mutations in RPGRIP1 have been shown to cause Leber congenital amaurosis, a group of retinal dystrophies that represent the most common genetic causes of congenital visual impairment in infants and children. Using the newly available canine genome sequence we sequenced RPGRIP1 in affected and carrier MLHDs and identified a 44-nucleotide insertion in exon 2 that alters the reading frame and introduces a premature stop codon. All affected and carrier dogs within an extended inbred pedigree were homozygous and heterozygous, respectively, for the mutation. We conclude the mutation is responsible for cord1 and demonstrate that this canine disease is a valuable model for exploring disease mechanisms and potential therapies for human Leber congenital amaurosis.

Treatment of upper motoneuron plantarflexion contractures by using an adjustable ankle-foot orthosis

OBJECTIVE

To assess the effectiveness of an adjustable ankle-foot orthosis in the treatment of plantarflexion contractures after central nervous system injury or disease.

DESIGN

Prospective, nonrandomized, interventional trial.

SETTING

University medical center's acute inpatient rehabilitation hospital.

PARTICIPANTS

Nine ankles with plantarflexion contractures that could not be passively reduced to less than neutral position occurring in 6 patients with stroke or other acquired brain injury.

INTERVENTION

To assure differentiation between spastic deformity and true contracture, patients received a 2% lidocaine block of the posterior tibial nerve. The adjustable ankle-foot orthosis was then applied on the affected ankle for 23 hours per day for 14 days. Adjustments to increase dorsiflexion passive range of motion (PROM) ranged from 0 degrees to 4.5 degrees and were attempted every 48 to 72 hours.

MAIN OUTCOME MEASURES

Dorsiflexion PROM at the ankle with the knee extended.

RESULTS

Increased PROM (average, 20.1 degrees; range, 6 degrees--36 degrees ) was statistically significant (p =.0078). Complications related to pressure with erythema or blister formation associated with pain occurred in 44% of treated ankles at some time during the 2-week trial period.

CONCLUSION

Plantarflexion contractures can be significantly reduced by using the adjustable ankle-foot orthosis with minimal complications.

An application of upper-extremity constraint-induced movement therapy in a patient with subacute stroke

BACKGROUND AND PURPOSE

The purpose of this case report is to demonstrate the application of constraint-induced movement therapy with an individual with upper-extremity hemiparesis within 4 months after sustaining a cerebrovascular accident (stroke). Such patients often fail to develop full potential use of their affected upper extremity, perhaps due to a "learned nonuse phenomenon."

CASE DESCRIPTION

The patient was a 61-year-old woman with right-sided hemiparesis resulting from an ischemic lacunar infarct in the posterior limb of the left internal capsule. The patient's less-involved hand was constrained in a mitten so that she could not use the hand during waking hours, except for bathing and toileting. On each weekday of the 14-day intervention period, the patient spent 6 hours being supervised while performing tasks using the paretic upper extremity. Pretreatment, posttreatment, and 3-month follow-up outcome measures included the Wolf Motor Function Test and the Motor Activity Log (MAL).

OUTCOMES

For the Wolf Motor Function Test, both the mean and median times to complete 16 tasks improved from pretreatment to posttreatment and from posttreatment to follow-up. Results of the MAL indicated an improved self-report of both "how well" and "how much" the patient used her affected limb in 30 specified daily tasks. These improvements persisted to the follow-up.

DISCUSSION

Two weeks of constraining the unaffected limb, coupled with practice of functional movements of the impaired limb, may be an effective method for restoring motor function within a few months after cerebral insult. Encouraging improvements such as these strongly suggest the need for a group design that would explore this type of intervention in more detail.

Correlation between Waardenburg syndrome phenotype and genotype in a population of individuals with identified PAX3 mutations

Waardenburg syndrome (WS) type 1 is an autosomal dominant disorder characterized by sensorineural hearing loss, pigmentary abnormalities of the eye, hair, and skin, and dystopia canthorum. The phenotype is variable and affected individuals may exhibit only one or a combination of several of the associated features. To assess the relationship between phenotype and gene defect, clinical and genotype data on 48 families (271 WS individuals) collected by members of the Waardenburg Consortium were pooled. Forty-two unique mutations in the PAX3 gene, previously identified in these families, were grouped in five mutation categories: amino acid (AA) substitution in the paired domain, AA substitution in the homeodomain, deletion of the Ser-Thr-Pro-rich region, deletion of the homeodomain and the Ser-Thr-Pro-rich region, and deletion of the entire gene. These mutation classes are based on the structure of the PAX3 gene and were chosen to group mutations predicted to have similar defects in the gene product. Association between mutation class and the presence of hearing loss, eye pigment abnormality, skin hypopigmentation, or white forelock was evaluated using generalized estimating equations, which allowed for incorporation of a correlation structure that accounts for potential similarity among members of the same family. Odds for the presence of eye pigment abnormality, white forelock, and skin hypopigmentation were 2, 8, and 5 times greater, respectively, for individuals with deletions of the homeodomain and the Pro-Ser-Thr-rich region compared to individuals with an AA substitution in the homeodomain. Odds ratios that differ significantly from 1.0 for these traits may indicate that the gene products resulting from different classes of mutations act differently in the expression of WS. Although a suggestive association was detected for hearing loss with an odds ratio of 2.6 for AA substitution in the paired domain compared with AA substitution in the homeodomain, this odds ratio did not differ significantly from 1.0.

Cosegregation of familial intestinal pseudoobstruction and presence of digital arches in a large multigenerational pedigree

Previous studies have suggested a relationship between the presence of digital arches and the occurrence of early-onset chronic intestinal pseudoobstruction (CIP). We recently had under our care a patient who died of complications from neuropathic familial CIP (FCIP) and who had family members with symptoms and radiographic findings consistent with FCIP. Our aim was to determine if there is a relationship between FCIP and digital arches using members of this patient's family tree. Questionnaires, telephone follow-up, and clinical and radiographic evidence were all utilized to determine whether a diagnosis of CIP could be made for the family members of this deceased FCIP patient. Fingerprints were sought for all study subjects. Eight of the 26 study subjects who were fingerprinted had clinically diagnosed FCIP and four of these eight had radiographic confirmation. All eight were positive for one or more arches (sensitivity = 100%). Only one of the 18 subjects without a diagnosis of FCIP who were fingerprinted had arches (specifically 94%). The likelihood of linkage between the presence of digital arches and FCIP in our study family was significant by genetic linkage analysis criteria. These results show a significant correlation between FCIP and digital arches (P < 0.0001). Whether this relationship is a causal one, ie, the gene responsible for digital arches is also responsible for FCIP, or is the result of linkage between the genes for FCIP and digital arches remains unclear.

Overcoming limitations in elbow movement in the presence of antagonist hyperactivity

BACKGROUND AND PURPOSE

A traditional perspective on rehabilitation of patients with abnormal muscular hyperactivity presumes that relaxation should be facilitated prior to recruitment of antagonists, if effective movement about a joint is to occur. The purpose of the study was to determine the effect of training weak triceps brachii muscles, with hyperactivity present in the opposing biceps brachii muscles, on elbow function in individuals at least 1 year poststroke.

SUBJECTS

Sixteen patients with chronic stroke were randomly assigned to receive electromyographic biofeedback to retrain the triceps muscle (n = 8) or to receive conventional movement training (n = 8).

METHODS

Both groups participated in 5 baseline and 10 training sessions involving tasks requiring elbow extension. Preintervention and postintervention measurements included elbow extension range of motion, triceps and biceps muscle electromyographic activity during performance of elbow extension, resisted elbow extension, and a reaching task.

RESULTS

Two-sample t-test results of between-group comparisons for each variable were not significant. One-sample t-test results of within-group comparisons showed significant increases in triceps muscle mean electromyographic activity during two of the three tasks for the feedback group, but not for the nonfeedback group. Passive and active range of motion in both groups increased significantly, although biceps muscle co-contraction persisted.

CONCLUSION AND DISCUSSION

These results suggest that functional improvements at the elbow may have been due to biomechanical (peripheral) rather than neuromuscular (central) changes about the joint. Furthermore, these preliminary data indicate that patients with stroke may be trained to increase movement without first being trained to specifically inhibit hyperactivity in muscles.

PRP38 encodes a yeast protein required for pre-mRNA splicing and maintenance of stable U6 small nuclear RNA levels

An essential pre-mRNA splicing factor, the product of the PRP38 gene, has been genetically identified in a screen of temperature-sensitive mutants of Saccharomyces cerevisiae. Shifting temperature-sensitive prp38 cultures from 23 to 37 degrees C prevents the first cleavage-ligation event in the excision of introns from mRNA precursors. In vitro splicing inactivation and complementation studies suggest that the PRP38-encoded factor functions, at least in part, after stable splicing complex formation. The PRP38 locus contains a 726-bp open reading frame coding for an acidic 28-kDa polypeptide (PRP38). While PRP38 lacks obvious structural similarity to previously defined splicing factors, heat inactivation of PRP38, PRP19, or any of the known U6 (or U4/U6) small nuclear ribonucleoprotein-associating proteins (i.e., PRP3, PRP4, PRP6, and PRP24) leads to a common, unexpected consequence: intracellular U6 small nuclear RNA (snRNA) levels decrease as splicing activity is lost. Curiously, U4 snRNA, normally extensively base paired with U6 snRNA, persists in the virtual absence of U6 snRNA.