Interviews Probe How Unaffected Siblings Learn Genetic Implications of SMA

Marisa Wexler MS avatar

by Marisa Wexler MS |

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Siblings of people with spinal muscular atrophy (SMA) who do not have the disease themselves tend to learn about it gradually over time from both their parents and external sources, a study shows.

Findings from interviews with families affected by SMA highlight the importance of parents discussing the risk of being an SMA carrier with their children after they are old enough to to fully grasp these ideas to avoid gaps in their understanding.

The study, “Communication about spinal muscular atrophy and genetic risk within families: An Australian pilot study,” was published in the Journal of Paediatrics and Child Health.

Biological siblings of people with SMA have a two-in-three chance of being carriers of the disease. That means that even though they don’t have SMA, they could pass the mutant gene to their children. It is therefore necessary for these siblings to understand the genetic risk. However, talking about genetic diseases in affected families can be complicated and fraught with emotion. Better understanding about how this information is — or isn’t — shared can help with developing strategies for more effective communication.

To examine these issues further, researchers in Australia conducted interviews with four siblings, ages 16–25, of people with SMA type 2 or type 3 from three different families. Interviews also were conducted with three parents from unrelated families who had young children both with and without SMA.

“We aim to explore whether and how siblings learn about SMA, particularly about the genetic implications for themselves,” the researchers wrote.

From the interviews, they derived four overarching themes about how SMA was discussed, or was planned to be discussed, in families. (It is notable that the interviews were conducted before any SMA treatment was available in Australia.)

The first theme, from the sibling interviews, was that information about SMA tended to be doled out “in bits and pieces” as children grew older.

“[My parents] always told us everything but I’d say just a bit dumbed down if we were younger and to feed a bit more information to us as we got a bit older,” one sibling said.

Often, there were early, brief conversations about SMA, in which parents would explain the disease and how it is inherited.

“The focus of these conversations was to explain the reason their affected sibling had inherited the condition, rather than to explain the genetic risk for the unaffected sibling,” the researchers wrote.

Subsequent conversations often were prompted by major life events, such as surgeries or the beginning of relationships. Siblings also reported seeking external sources of information, ranging from the internet to genetic counselors.

The second theme, also derived from the sibling interviews, was that SMA can be difficult to talk about because of the emotional nature of these conversations. Children often were hesitant to ask their parents for fear of causing undue stress or discomfort. All of the siblings reported a period in their late teens or early 20s when they fully came to grips with the prognosis of SMA.

“All said that they ultimately felt their relationship with their brother or sister with SMA had strengthened over this period,” the researchers wrote.

The third theme was that all parents in the study planned to gradually explain SMA carrier risk to their children when they were 8 to 14 years old. While parents generally expressed a desire to be open and honest with their children, they also didn’t want to scare them — in regards to their own health or that of their siblings. They also expressed concerns about how to phrase information in an age-appropriate manner.

Previous research has suggested that children are not fully able to  comprehend genetic risk, as it pertains to their own potential reproduction, until they are 15 or older. As such, having these discussions with younger children before they are able to understand these concepts could lead to misconceptions or gaps in their knowledge.

The fourth and final theme was a feeling that more public awareness of SMA would be beneficial to the family as a whole, as well as a desire for additional emotional and social support — both for the affected individuals and their families.

“To have an option of coming in [to a medical institution] as a whole family and to have someone help us explain it would be a great thing. Because there will always be questions that they’ll answer that we can’t answer,” one parent said.

Because this study was done in one place with relatively few participants, the results likely aren’t representative of every family affected by SMA.

“Therefore, the findings are not intended to be [generalizable] to all families with SMA but raise themes that may be relevant to many families,” the researchers wrote.

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