Assessing methylation status
Methylation status of 4q35 is traditionally assessed after FSHD1 testing is negative. Methylation sensitive restriction enzyme (MSRE) digestion showing hypomethylation has long been considered diagnostic of FSHD2. Other methylation assays have been proposed or used in research settings, including methylated DNA immunoprecipitation and bisulfite sequencing, but are not routinely used in clinical practice. Bisulfite sequencing, if validated, would be valuable due to it being able to use lower quality DNA sources, such as those found in saliva. Auxiliary testing
Other tests can support the diagnosis of FSHD, although they are all less sensitive and less specific than genetic testing. Nonetheless, they can rule out similar-appearing conditions. Creatine kinase (CK) blood level is often ordered when muscle damage is suspected. CK is an enzyme found in muscle, leaking into the blood when muscles become damaged. In FSHD, CK level is normal to mildly elevated, never exceeding five times the upper limit of normal. Electromyogram (EMG) measures the electrical activity in the muscle. EMG can show nonspecific signs of muscle damage or irritability. Nerve conduction velocity (NCV) measures the how fast signals travel along a nerve. The nerve signals are measured with surface electrodes (similar to those used for an electrocardiogram) or needle electrodes. Muscle biopsy is the surgical removal and examination of a small piece of muscle, usually from the arm or leg. Microscopy and a variety of biochemical tests are used for examination. Findings in FSHD are nonspecific, such as presence of white blood cells or variation in muscle fiber size.
Felodipine is a medication of the calcium channel blocker type which is used to treat high blood pressure. It was patented in 1978 and approved for medical use in 1988. Medical uses
Felodipine is used to treat high blood pressure and stable angina.It should not be used for people who are pregnant, have acute heart failure, are having a heart attack, have an obstructed heart valve, or have obstructions that block bloodflow out of the heart.For people with liver failure the dose needs to be lowered, because felodipine is cleared by the liver. Adverse effects
The only very common side effect, occurring in more than 1/10 people, is pain and swelling in the arms and legs.Common side effects, occurring in between 1% and 10% of people, include flushing, headache, heart palpitations, dizziness and fatigue.Felodipine can exacerbate gingivitis. Interactions
Felodipine is metabolized by cytochrome P450 3A4, so substances that inhibit or activate CYP3A4 can strongly effect how much felodipine is present.CYP3A4 inhibitors, which increase the amount of felodipine available per dose, include cimetidine, erythromycin, itraconazole, ketoconazole, HIV protease inhibitors, and grapefruit juice.CYP3A4 activators, which decrease the amount of felodipine available per dose, include phenytoin, carbamazepine, rifampicin, barbiturates, efavirenz, nevirapine, and Saint Johns wort. Mechanism of action
Felodipine is a calcium channel blocker.