ABSTRACT
Congenital myotonic dystrophy is a severe and early-onset form of myotonic dystrophy (DM) with a prevalence of 2.5-5.5/100,000 live births. Expansion of the trinucleotide CTG repeat in the 3 untranslated region of the DM gene, which is located at a chromosome 19q13.3 is a common mutation in DM. Clinical features are generalized hypotonia (floppy infant), respiratory and feeding difficulty, and the neonatal mortality rate is approximately 40%. We experienced a case of recurrent congenital myotonic dystrophy, and report with a review of related literatures. Women with recurrent neonatal hypotonia or ultrasonographic evidence of hypotonia, including positional abnormalities of the extremities and idiopathic polyhydramnios, should be offered testing for the genetic studies for myotonic mutation, such as PCR (Polymerase chain reaction) analysis and Southern blot analysis.
Subject(s)
Female , Humans , Infant , Blotting, Southern , Diagnosis , Extremities , Infant Mortality , Live Birth , Muscle Hypotonia , Myotonic Dystrophy , Polyhydramnios , Polymerase Chain Reaction , Prenatal Diagnosis , Prevalence , Untranslated RegionsABSTRACT
Congenital myotonic dystrophy is a severe and early-onset form of myotonic dystrophy (DM) with a prevalence of 2.5-5.5/100,000 live births. Expansion of the trinucleotide CTG repeat in the 3 untranslated region of the DM gene, which is located at a chromosome 19q13.3 is a common mutation in DM. Clinical features are generalized hypotonia (floppy infant), respiratory and feeding difficulty, and the neonatal mortality rate is approximately 40%. We experienced a case of recurrent congenital myotonic dystrophy, and report with a review of related literatures. Women with recurrent neonatal hypotonia or ultrasonographic evidence of hypotonia, including positional abnormalities of the extremities and idiopathic polyhydramnios, should be offered testing for the genetic studies for myotonic mutation, such as PCR (Polymerase chain reaction) analysis and Southern blot analysis.
Subject(s)
Female , Humans , Infant , Blotting, Southern , Diagnosis , Extremities , Infant Mortality , Live Birth , Muscle Hypotonia , Myotonic Dystrophy , Polyhydramnios , Polymerase Chain Reaction , Prenatal Diagnosis , Prevalence , Untranslated RegionsABSTRACT
For the investigation of the receptive field of the retinal neurons, the spatial and temporal properties of horizontal cells and the center-surround antagonisms of bipolar cells and the third-order neurons were studied using conventional intracellular recording techniques. Horizontal cells were hyperpolarized by the large annulus light stimuli (id: 3.5mm) and required at least 0.2 seconds of dark periods to respond enough. The amplitudes of the response of the ON-bipolar cell were decreased as the diameter of the spot stimuli was increased to 2.6mm and the responses were inverted at 2.6mm of inner diameter of the spreading annulus stimuli with fixed width. ON-sustained cell with spikes generated ON-sustained light responses by small annulus (1400-2100micrometer), but elicited OFF-sustained responses by large annulus (2100-2800micrometer). ON-sustained cell without spikes also showed surround antagonism. The spikes were generated at the spot of 490micrometer diameter and they were disappeared at the spot of 5600micrometer diameter. And, OFF-transient component of the ON-OFF transient cell was enhanced as annulus stimuli spread. The results suggest that the horizontal cells have large and monotonic receptive fields while the bipolar cells and the ON-sustained cells have large biphasic receptive fields in the catfish retina.