Genetic factors contribute to heart disease. In this study, linkage analyses have been performed in a family that is predisposed to sudden death from cardiac arrhythmias, the long QT syndrome (LQT). A DNA marker at the Harvey ras-1 locus (H-ras-1) was linked to LQT with a logarithm of the likelihood ratio for linkage (lod score) of 16.44 at theta = 0, which confirms the genetic basis of this trait and localizes this gene to the short arm of chromosome 11. As no recombination was observed between LQT and H-ras-1, and there is a physiological rationale for its involvement in this disease, ras becomes a candidate for the disease locus.

It is well documented that children with neurofibromatosis type 1 are at high risk for a variety of cognitive and learning deficits. The current study investigated the use of a developmental screening tool, the Parents' Evaluation of Developmental Status: Developmental Milestones, as an accurate, reliable, and efficient indicator of developmental delays. Sixty-eight percent of children with neurofibromatosis type 1 were found to have a developmental delay in at least 1 of the 8 areas tested by the Parents' Evaluation of Developmental Status: Developmental Milestones. Significant developmental abnormalities were found in the areas of fine motor (35%), gross motor (52%), and math/premath (31%). A positive association was found between the presence of a previously diagnosed optic glioma and math/premath delays (χ(2) = 0.0022) and between male sex and fine motor delays (χ(2) = 0.0325). The Parents' Evaluation of Developmental Status: Developmental Milestones assessment demonstrates the high presence of developmental delays in children with neurofibromatosis type 1 and the need for aggressive and early screening.

Children with neurofibromatosis type 1 exhibit a variety of developmental delays. However, there is little information about the progression of these deficits over the course of development. Using the Parents' Evaluation of Developmental Status measurement tool, we assessed 124 infants (0-2 years of age), preschool-age children (3-5 years of age), and school-age children (6-8 years of age) with neurofibromatosis type 1 to define the natural history of delays. School-age children exhibited significantly more areas of delay than infants or preschool-age children. Delays in math, reading, gross motor, fine motor, and self-help development were observed more frequently in older than younger children. Finally, analysis of 43 subjects for whom longitudinal assessments were available revealed that children often migrated between delayed and nondelayed groups in all areas except gross motor development. Based on these findings, we advocate early developmental screening and intervention for this at-risk pediatric population, especially in the area of gross motor function.

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Knee-ankle-foot orthosis with dynamic ankle and fixed knee are poorly tolerated and are not beneficial in preventing a reduction in ankle-foot dorsiflexion range of motion in children with spastic cerebral palsy, at least with limited use.

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There are currently no objective criteria to evaluate pediatric hypotonia. The purpose of this pilot study was to identify diagnostic criteria for assessing hypotonia in children with Neurofibromatosis type 1 (NF1). Fifty-five subjects between the ages of 1 and 7 years with a diagnosis of NF1 were evaluated. A physical therapist recorded a subjective tone assessment and objective tone metrics, including ankle dorsiflexion, knee extension, hip abduction, triceps fat percentage, grip strength and head lag during a pull-to-sit test. Multivariate logistic regression analysis showed the presence of head lag paired with increased hip range of motion was a significant predictor of hypotonia. The presence of head lag on a pull-to-sit test paired with increased hip range of motion is an accurate predictor of hypotonia in children with NF1. These objective measures should be prospectively evaluated in other pediatric populations for their ability to predict hypotonia.

Children with the neurofibromatosis type 1 (NF1) inherited tumor predisposition syndrome are at risk for the development of brain tumors. In addition, children with neurofibromatosis type 1 often exhibit low tone (hypotonia). In this study, the authors explored the hypothesis that hypotonia could be a clinical indicator of glioma in children with neurofibromatosis type 1. A total of 56 children between 1 and 7 years of age with a confirmed diagnosis of neurofibromatosis type 1 were evaluated. Brain magnetic resonance imaging (MRI) was available for 19 of these children. Chi-square analysis demonstrated a statistically significant correlation between hypotonia and glioma in children with neurofibromatosis type 1 (90% sensitivity and 78% specificity). These results suggest that hypotonia might be a clinically useful indicator of brain tumor in this at-risk population.