1/31. A novel sodium channel mutation in a family with hypokalemic periodic paralysis.OBJECTIVE: To identify the cause of hypokalemic periodic paralysis (HOKPP) in a family whose disease is not caused by a mutation in the dihydropyridine-sensitive (DHP) receptor alpha1-subunit gene (CACNA1S). BACKGROUND: hypokalemic periodic paralysis is primarily caused by mutations within CACNA1S. genetic heterogeneity for HOKPP has been reported, but no other locus has been identified. methods: Single-stranded conformational polymorphism (SSCP) analysis and PCR direct sequencing were used to screen the skeletal muscle alpha1-sodium channel gene (SCN4A) for a mutation in our family. RESULTS: SSCP analysis showed an abnormally migrating conformer in exon 12. Direct sequencing of the conformer showed a guanine to adenine transition at position 2006 in the cDNA sequence; this results in an amino acid substitution of a highly conserved arginine (Arg) to histidine (His) at position 669. This sequence alteration segregated only with the affected members of the kindred and was not found in a panel of 100 dna samples from healthy controls. The amino acid substitution alters the outermost positive charge in the membrane spanning segment DII/S4, which is involved in voltage sensing. CONCLUSIONS: The first arginine in DII/S4 and in DIV/S4 within the skeletal muscle sodium channel and the L-type calcium channel genie CACNA1S appear to be critical for normal function. In all four cases, Arg to His mutations result in a disease phenotype. The identification of a mutation within the skeletal muscle sodium channel resulting in hypokalemic periodic paralysis represents a novel finding.- - - - - - - - - - ranking = 1keywords = hypokalemic (Clic here for more details about this article) |
2/31. Familial hypokalemic periodic paralysis and wolff-parkinson-white syndrome in pregnancy.PURPOSE: To describe the anesthetic and obstetrical management of a pregnant patient with co-existing Familial hypokalemic periodic paralysis (FHPP) and wolff-parkinson-white syndrome (WPW). CLINICAL FEATURES: A 29 yr-old primigravida with FHPP and WPW presented to the antenatal clinic at 18 wk gestation, for consideration of her anesthetic and obstetrical management during labour and delivery. A plan was constructed to avoid the known precipitating factors of FHPP including carbohydrate loading, cold, mental stress and exercise, which could lead to acute attacks of weakness. She presented for induction of labour at 41 wk and three days. An epidural catheter was sited early in labour. The second stage was limited to less than one hour. She had a rotational forceps delivery for which the epidural was extended to provide anesthesia. A healthy male baby was delivered. The patient made an uncomplicated recovery and was discharged home on the second postnatal day. The peripartum potassium was kept within the normal range with intravenous as well as oral potassium supplementation. No arrhythmias were reported. CONCLUSION: Assessment of the patient at an early stage in her pregnancy allowed for a multidisciplinary approach to this patient and her medical problems. A plan was made to avoid known precipitating factors during labour, delivery and the postnatal period well in advance of her date of confinement, leading to a successful outcome for mother and child.- - - - - - - - - - ranking = 0.66666666666667keywords = hypokalemic (Clic here for more details about this article) |
3/31. Hypokalemic thyrotoxic paralysis: a rare cause of tetraparesis with acute onset in Europeans.We describe a 21-year-old Italian male affected by hypokalemic tetraparesis with acute onset. In the emergency ward, the patient was agitated, with tachycardia (140/min) and systolic hypertension (180/70 mm Hg). He was not able to flex the lower extremities against a light resistance and furthermore, he was hypotonic and without tendon reflexes. One hour later he developed strength deficit of the upper extremities as well. Biochemical analyses revealed severe hypopotassemia (2.1 meg/l). After administration of 140 meq potassium phosphate, the patient began to improve, and 12 h after the onset he was able to walk normally. Successive investigations documented an undiagnosed case of Graves' disease. Thyrotoxic hypokalemic paralysis has been observed almost only in Asians, however, with this case and others reported, we believe that it should be considered as a cause of muscular paralysis also in Caucasians.- - - - - - - - - - ranking = 0.33333333333333keywords = hypokalemic (Clic here for more details about this article) |
4/31. Clinical-molecular study of a family with essential tremor, late onset seizures and periodic paralysis.We report the clinical features of, and the molecular study performed on, a Spanish family with essential tremor (ET), late onset epilepsy and autosomal dominant hypokalemic periodic paralysis (hypoPP). The presence of hypoPP in this kindred suggested an ion channel as a candidate gene for ET. Our study identified an Arg528His CACNL1A3 mutation in patients with hypoPP, and excluded this mutation as the cause of tremor or epilepsy in this kindred.- - - - - - - - - - ranking = 0.16666666666667keywords = hypokalemic (Clic here for more details about this article) |
5/31. Thyrotoxic periodic paralysis in a Caucasian man in treatment for Graves' disease.Thyrotoxic periodic paralysis (TPP) is the main secondary form of hypokalemic periodic paralysis and is mostly associated with Graves' disease. Initially diagnosed in Asian countries, TPP has been sporadically reported in different populations of the western world. Increased Na /K( )-ATPase activity seems to be responsible for the marked hypokalemia observed during the transient paralysis attacks. We report on a 35-year-old Italian man without history of hypokalemic periodic paralysis and hyperthyroidism, in treatment for Graves' disease, who suffered episodes of flaccid paralysis even with normal thyroid hormone levels. An insulin-glucose provocation test confirmed our diagnosis. Oral and parenteral potassium reverse the symptoms. Monitoring of thyroid function is also important to prevent further attacks.- - - - - - - - - - ranking = 0.33333333333333keywords = hypokalemic (Clic here for more details about this article) |
6/31. muscle weakness in a Japanese family of Arg1239His mutation hypokalemic periodic paralysis.Familial hypokalemic periodic paralysis is an autosomal dominant disorder. Recently, three predominant mutations were found in the muscle dihydropyridine-sensitive calcium channel alpha 1-subunit gene. We present a Japanese family that displays one of these, the Arg1239His mutation. All the affected individuals of this family displayed this mutation. Two cases had a history of recurrent episodes of muscle weakness and difficulty in running before their first paralytic attack. It is suggested that there are no racial differences with this mutation, and that mild muscle weakness occurs not only after but also preceding the first attack.- - - - - - - - - - ranking = 0.83333333333333keywords = hypokalemic (Clic here for more details about this article) |
7/31. hypokalemic periodic paralysis associated with malignant hyperthermia.hypokalemic periodic paralysis is in most cases related to mutations within the dihydropyridine receptor gene. Susceptibility to malignant hyperthermia has been linked to a different part of the same gene, but is more frequently caused by mutations within the ryanodine receptor gene. We report the association of the two disorders in a patient for whom the most frequent mutations for hypokalemic periodic paralysis were not found. This suggests further genetic heterogeneity of this condition, the interest of this case residing in the known coupling between dihydropyridine and ryanodine receptors.- - - - - - - - - - ranking = 0.16666666666667keywords = hypokalemic (Clic here for more details about this article) |
8/31. Two novel mutations of thiazide-sensitive Na-Cl cotrans porter (TSC) gene in two sporadic Japanese patients with gitelman syndrome.gitelman syndrome is a renal disorder characterized by hypokalemia, hypomagnesemia, metabolic alkalosis and hypocalciuria due to the defective tubular reabsorption of magnesium and potassium. This disease is caused by mutations of thiazide-sensitive Na-Cl cotransporter (TSC) gene. gitelman syndrome is usually distinguished from bartter syndrome by the presence of both hypomagnesemia and hypocalciuria. However, a phenotypic overlap is sometimes observed. We encountered two sporadic Japanese patients with gitelman syndrome and analyzed their TSC gene. These patients were diagnosed as gitelman syndrome by the typical clinical findings and biochemical abnormalities, such as mild muscular weakness, periodic paralysis, tetany, metabolic alkalosis, hypomagnesemia and hypocalciuria. In patient 1, a novel two base deletion (del TG at nucleotide 731 and 732) in exon 5 and a two base deletion (del TT at nucleotide 2543 and 2544) in exon 21 previously reported in a Japanese patient were identified. The patient 2 had a missense mutation (L623P), that was also identified in Japanese patients, and a novel in-frame 18 base insertion in exon 6 as a heterozygous state. family analysis of two patients confirmed an autosomal recessive inheritance. In conclusion, we add two new mutations of the TSC gene in Japanese patients with gitelman syndrome. Because the differential diagnosis between bartter syndrome and gitelman syndrome is sometimes difficult, molecular analysis would be a useful diagnostic tool, particularly in unusual cases with phenotypic overlapping.- - - - - - - - - - ranking = 8.2031095178156E-5keywords = alkalosis (Clic here for more details about this article) |
9/31. Axonal hyperpolarization associated with acute hypokalemia: multiple excitability measurements as indicators of the membrane potential of human axons.Multiple nerve excitability measurements have been proposed for clinical testing of nerve function, and an important determinant of excitability is membrane potential. We report a patient with acquired hypokalemic paralysis in whom multiple excitability indices (stimulus-response curve, strength-duration properties, threshold electrotonus, recovery cycle) were measured during and after an acute hypokalemic attack (serum K( ) level, 2.1 mEq/L and 4.5 mEq/L, respectively). During hypokalemia, there was a shift of the stimulus-response curve to the right, a decrease in strength-duration time constant, a "fanning-out" of responses during threshold electrotonus, a reduction in relative refractory period, and an increase in superexcitability; all of these indicate axonal hyperpolarization, presumably due to the K( ) equilibrium potential being more negative. These indices returned to normal 20 h later, associated with normalization of the serum K( ) level. These results demonstrate that the changes associated with hypokalemic paralysis are not confined to muscle and that axons undergo hyperpolarization in vivo. Multiple excitability measurements can be used as a tool to identify changes in membrane potential of human axons.- - - - - - - - - - ranking = 0.5keywords = hypokalemic (Clic here for more details about this article) |
10/31. acetazolamide-induced muscle weakness in hypokalemic periodic paralysis.A 46-year-old man with hypokalemic periodic paralysis (HypoPP) and diabetes mellitus (DM) had worsened muscle weakness after acetazolamide (ACZ) treatment. During the paralytic episode, serum potassium levels were reduced, and serum chloride and insulin levels were increased. The data suggested proximal renal tubular acidosis due to ACZ. We determined arterial-venous concentrations of potassium, insulin and glucose across the forearm. Venous potassium levels were markedly reduced. ACZ is thought to potentiate potassium uptake into muscles. Hyperinsulinemia and DM could contribute to ACZ-induced exacerbation in our patient. We should pay more attention to ACZ-treated HypoPP patients with hyperinsulinemia and DM.- - - - - - - - - - ranking = 0.83333333333333keywords = hypokalemic (Clic here for more details about this article) |
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