Fetal akinesia: Description, Causes and Risk Factors:
Fetal akinesia refers to a broad spectrum of disorders in which the unifying feature is a reduction or lack of fetal movement. Fetal akinesias may be caused by defects at any point along the motor system pathway including the central and peripheral nervous system, the neuromuscular junction and the muscle, as well as by restrictive dermopathy or external restriction of the fetus in utero.
The fetal akinesias are clinically and genetically heterogeneous, with causative mutations identified to date in a large number of genes encoding disparate parts of the motor system. However, for most patients, the molecular cause remains unidentified. One reason for this is because the tools are only now becoming available to efficiently and affordably identify mutations in a large panel of disease genes.
The underlying etiologies are diverse and include central nervous system (CNS) dysgeneses and primary myopathies. Persistent central nuclei or the presence of myotubes is often regarded as evidence of a primary myopathic etiology; however, these findings are also associated with impaired fetal innervation.
The etiology of decreased fetal movement is heterogeneous, thus identification of the underlying cause is necessary to predict recurrence risk and patient outcome. Fetal akinesia may result from truncating mutations in RAPSN or DOK7. Other causes include primary neurogenic, prenatal exposure, and circulating maternal antibodies to the acetylcholine receptor. The protein encoded by DOK7 induces autophosphorylation of the skeletal muscle receptor-like tyrosine kinase, a key protein involved in postsynaptic differentiation. The protein rapsyn acts as a link connecting the acetylcholine receptor to the cytoskeleton-anchored dystrophin-glycoprotein complex at the neuromuscular junction.
Next-generation sequencing offers the promise, if sufficient cohorts of patients can be assembled, to identify the majority of the remaining genes on a research basis and facilitate efficient clinical molecular diagnosis. The benefits of identifying the causative mutation(s) for each individual patient or family include accurate genetic counselling and the options of prenatal diagnosis or preimplantation genetic diagnosis.
The disease is characterized by prenatal onset growth deficiency, multiple joint contractures, facial anomalies,hypoplastic dermal ridges, and pulmonary hypoplasia. Patients are often stillborn and most liveborn patients succumb to theeffects of pulmonary hypoplasia
in the first month of life. Head circumference is often normal. Patients have contractures ofmultiple joints including wrists, ankles, elbows, knees, and hips. Limbs are also affected by captodactyly, rocker bottom feetand clubfoot. Craniofacial features include an apparently short neck, simple and posteriorly rotated ears, hypertelorism,prominent eyes, epicanthal folds, micrognathi
a, small mouth, and high arched palate. Affected pregnancies may becomplicated by polyhydramnios and some patients are born prematurely. Other findings at birth include a short umbilicalcord and small placenta.
Tests: Testing of the two genes is carried out in the order specified by the client. Testing isaccomplished by amplifying the coding exons and ~50 bp of adjacent noncoding sequence, then determining the nucleotidesequence using standard dideoxy sequencing methods and a capillary electrophoresis instrument.Analytical sensitivity may be limited because some reported DOK7 mutations are not expected to bedetected by genomic DNA sequencing. Clinical sensitivity may be low becausefetal akinesia has multiple underlying causes including environmental, immunological, and genetic.
No completely successful approach to treat fetal akinesia has been found. Goals include lower-limb alignment and establishment of stability for ambulation and upper-limb function for self-care. Early gentle manipulation soon after birth improves passive and active range of motion. This is especially true in the case of the inherited distal arthrogryposes, in which prolonged immobilization associated with casting may be undesirable. Late manipulation is of little value.
Early vigorous physical therapy to stretch contractures is very important in improving joint motion and avoiding muscle atrophy. Your child's doctor may prescribe physical and occupational therapy to increase your child's muscle strength and improve flexibility. Splints can also increase your child's range of motion. A removable splint works so that the joints can be moved and muscles exercised periodically. In some cases, merely wearing a splint at night may be sufficient.
Surgical Options: Your child's doctor may recommend surgery to improve how she can position and move her limbs. These procedures may include muscle releases, tendon transfers or bony fusions to improve flexibility and correct deformities.
NOTE: The above information is for processing purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.