Stroke Risk and Screening in Sickle Cell Disease

As early as the disease is detected, sometimes as young as two months of age.

The best outcomes are under 16 years, 16 to 25 is still viable, and beyond 25 the risks rise and require much more detailed pre-transplant workup, including cardiac and kidney function assessment, though age is not always a fixed barrier if organ function is well preserved and the family is fully committed. A full-match sibling transplant typically costs around $24,000 to $25,000, rising for older patients closer to adult body weight, while a half-match or unrelated-donor transplant through a registry costs around $33,000 to $34,000, since registry and donor-related costs are higher even though complications are reduced.

Gene therapy uses the patient's own stem cells rather than a donor, mobilised and collected the same way as for a transplant, then modified in a laboratory using either a viral vector for gene addition or CRISPR-Cas9 editing to correct the underlying genetic change, a process that currently takes around six months. Because the cells being returned are the patient's own, recovery is generally faster than with a donor transplant, but the therapy currently has FDA approval only for patients aged 12 and older, and it remains expensive and not yet widely available outside the US, Europe and a handful of other countries.

If finances are genuinely not a barrier, gene therapy is worth choosing once it is better established, since it avoids the donor-related risks. But where finances are a limiting factor, an experienced allogeneic bone marrow transplant programme should still be trusted: it has decades of mature outcome data behind it, and families should not exhaust all their resources chasing a gene therapy process that could stall partway through. If a patient is having an acute crisis such as a recent stroke, there is also often not enough time to wait the six to eight months gene therapy currently requires, and transplant should be pursued instead.

Parents are usually a half match by default, provided they are not sicklers themselves and have no disqualifying condition such as HIV or organ damage. A full-match sibling occurs in about 25% of cases, and a half-matched sibling is actually a better donor than a half-matched parent, since sibling cells are better tolerated with fewer pre-existing antibody reactions. Beyond parents and siblings, more distant relatives such as aunts, uncles or cousins are rarely even a half match, so realistic donor availability is mostly limited to the immediate family.

Transcranial Doppler ultrasound, which measures blood flow velocity in the cerebral vessels. The first scan is recommended at two years of age, with follow-up frequency depending on whether the result is normal or abnormal.

The middle and posterior cerebral artery territories are affected most often, though the anterior territory can occasionally be involved as well.