All of the muscle diseases associated with dysferlin deficiency have an autosomal recessive inheritance, so a person will only have symptoms if he/she inherits a mutated version of the dysferlin gene from both parents. Children of someone with Dysferlinopathy/LGMD2B/Miyoshi will definitely be a carrier of one dysferlin mutation because each child inherits one of their dysferlin genes from the affected parent who carriers a dysferlin mutation on each of their copies of the dysferlin gene. In the absence of a spontaneous mutation, the children of an affected individual will only develop symptoms if they inherit a second mutated dysferlin gene from the other unaffected parent. Based on the incidence of these conditions in the general population, there are probably only about 3-5 people out of every thousand who have one copy of a mutated dysferlin gene (carriers). So, the chance of children inheriting these conditions is quite small unless the other unaffected parent has a family history of these conditions or shares a common ancestry with the affected parent.
If both parents have one copy of a mutated dysferlin gene, each child has a 25% chance of getting both defective copies and thus the disease. However, for each child of this same couple there is also a 50% chance of being a carrier of the defective gene, meaning that he/she has a single mutated copy of the gene but does not show any symptoms. Genetic testing in families with recessive disorders is sometimes advisable in order to detect carriers. It might also be good to determine whether the potential spouses of carriers or affected individuals are also carriers. Determination of a person's carrier status requires testing his/her DNA (rather than antibody testing for the dysferlin protein), since a carrier still expresses dysferlin protein from their good copy of the dysferlin gene.