Why Children of Parents with AA Genotype Cannot Inherit AS — Doctors Explain

Public health experts have clarified that reports of children with an AS genotype born to AA-genotype parents are almost always the result of laboratory errors, sample mix-ups, or rare genetic anomalies, rather than a biological possibility.

Doctors explained that two AA parents can only pass on the A gene, meaning their children would normally have an AA genotype. Conflicting results are usually caused by inaccurate genotype testing due to poor lab techniques, misinterpretation of uncommon haemoglobin variants, or the use of rapid tests without confirmatory procedures.

In exceptional cases, rare mutations or mix-ups at birth can create confusion, but these instances are extremely uncommon. Experts advise families in such situations to repeat genotype testing in accredited reference laboratories and avoid assuming infidelity when a child’s genotype appears inconsistent with their parents’.

The clarification follows discussions on social media, where some users claimed to be AS while both parents were reported as AA, prompting debates about paternity. Specialists emphasized that genotype testing is a laboratory-based method used to determine an individual’s genetic makeup, identify inherited blood disorders like sickle cell disease, and assess genetic compatibility for family planning.

Sickle cell disease (SCD) is an inherited blood disorder where red blood cells become misshapen, reducing their ability to carry oxygen efficiently and leading to complications such as pain, infections, stroke, and acute chest syndrome. Nigeria has the highest SCD burden, with approximately 150,000 newborns affected each year.

Public health professionals, including Dr. Rotimi Adesanya, explained that while AA parents are expected to have AA children, rare exceptions can occur due to lab errors, gene mutations, or mix-ups during childbirth—though these are extremely rare, about one in a million. He stressed that inaccurate testing is the most common cause of confusion, urging couples to confirm their genotypes in government-recognized reference laboratories.

“Normally, AA parents will have AA children. Most discrepancies arise from lab errors or uncommon variants of the S gene, such as SC, SE, which may be misinterpreted as AS,” Adesanya said. He also mentioned rare biological factors, like fused twins, that can result in unusual genetic outcomes but stressed these are exceptional cases.

Dr. Adesanya warned against hasty conclusions or accusations of infidelity, recommending that families repeat tests in accredited reference labs to verify results. He shared cases where children initially thought to be AS were later confirmed to have AA genotype after accurate testing.

Similarly, Dr. Babatunde Adewumi noted that it is not genetically possible for two AA parents to have an AS child, as a child can only inherit the S gene if at least one parent carries it. He explained that laboratory errors, poor techniques, or misinterpretation of results are the most common causes of such discrepancies.

Adewumi added that uncommon haemoglobin variants like Hb C, D, or E can interfere with standard genotype results and be misread as A or S. Advanced tests, such as HPLC or DNA analysis, can resolve these uncertainties. DNA testing is considered the most definitive method but is usually reserved for cases where standard testing produces conflicting results.

In conclusion, experts emphasized that AA parents producing an AS child is almost always due to errors, not biology, and families should rely on accredited testing and scientific verification to clarify any discrepancies.