Researchers discovered a new genetic mutation in a baby girl who had dangerously low levels of magnesium and calcium in her blood, which caused seizures. This rare inherited condition, called familial hypomagnesaemia with secondary hypocalcaemia (HSH), happens when a gene called TRPM6 doesn’t work properly. The good news is that when doctors caught the problem early and gave the baby magnesium supplements, she stopped having seizures and stayed healthy. This case shows why finding and treating this condition quickly is so important for babies’ health and development.

The Quick Take

  • What they studied: A rare genetic disease where babies are born unable to absorb enough magnesium from food, which then causes their calcium levels to drop dangerously low, leading to seizures
  • Who participated: One infant girl with the condition who presented with seizures in early infancy
  • Key finding: The baby had a new genetic mutation (two different changes in the TRPM6 gene) that prevented her body from properly managing magnesium and calcium levels, but daily magnesium supplements completely stopped her seizures
  • What it means for you: If a baby has unexplained seizures and low calcium levels, doctors should check magnesium levels and consider this rare genetic condition. Early diagnosis and treatment with magnesium supplements can prevent serious brain damage and allow children to develop normally

The Research Details

This is a case report, which means doctors documented the medical story of one patient with an unusual condition. The baby girl came to the hospital having seizures, and doctors ran blood tests that showed very low magnesium and calcium levels. They tested her thyroid, parathyroid glands, and vitamin D levels to rule out other causes. When magnesium supplements didn’t work at first, she came back to the hospital. The second time, doctors started her on long-term magnesium supplements, and she improved dramatically. Doctors then did genetic testing and found two different mutations in the TRPM6 gene, which had never been seen together before in this condition.

The TRPM6 gene is like an instruction manual that tells the body how to absorb magnesium from food. When this gene has mistakes in it, the body can’t absorb magnesium properly, causing levels to drop. Low magnesium then causes calcium levels to drop too, and this combination triggers seizures in babies’ developing brains.

This case is important because it describes a new genetic pattern that doctors hadn’t seen before. The baby had two different genetic mutations (one from each parent) rather than two copies of the same mutation, which is more common in this disease.

Case reports like this help doctors recognize rare diseases they might otherwise miss. When doctors understand that a baby’s seizures might be caused by low magnesium from a genetic problem, they can test for it and start the right treatment quickly. Quick treatment prevents permanent brain damage and allows the child to grow up healthy.

This is a single case report, so it describes what happened to one patient rather than comparing many patients. Case reports are useful for identifying new disease patterns and teaching doctors about rare conditions, but they can’t prove that something works for everyone. The genetic testing was thorough and identified a new mutation pattern, which adds scientific value. The fact that the baby stayed healthy for follow-up visits after treatment started is a good sign that the diagnosis and treatment were correct.

What the Results Show

The baby girl presented to the hospital with seizures, which are the most common first sign of this genetic condition in infants. Blood tests showed dangerously low magnesium (hypomagnesaemia) and low calcium (hypocalcaemia). Doctors tested other possible causes like thyroid problems, parathyroid problems, and vitamin D deficiency, but all those tests came back normal. This pattern of results pointed to a problem with magnesium absorption specifically.

Genetic testing revealed the baby had two different mutations in the TRPM6 gene: one mutation called c.5785del and another called c.3179T>A. This was a new combination that hadn’t been reported before in medical literature. Each parent carried one of these mutations without showing symptoms, which is typical for recessive genetic diseases.

The treatment was straightforward: daily magnesium supplements by mouth. After starting this treatment, the baby’s seizures stopped completely. At follow-up visits, she remained seizure-free and showed normal development with no complications from her earlier seizures.

The case highlights that this condition can be easily missed if doctors don’t think to check magnesium levels. The baby’s first hospital visit didn’t immediately lead to diagnosis, and she had to be readmitted before the right treatment started. This delay could have caused permanent brain damage, but fortunately the baby recovered fully. The case also shows that calcitonin (a hormone that helps regulate calcium) was undetectable, which is another clue that points to this specific genetic condition rather than other causes of low calcium.

Most cases of this genetic disease involve two copies of the same mutation in the TRPM6 gene. This case is unusual because the baby inherited two different mutations, one from each parent. Previous research has described many different mutations that cause this disease, but this particular combination of two different mutations is new to medical science. The good outcome with magnesium supplementation matches what doctors have seen in other cases, confirming that early treatment is the key to preventing permanent damage.

This is a single case report, so we can only say what happened to this one baby, not what will happen to all babies with this condition. We don’t have long-term follow-up data beyond the last consultation mentioned in the report. The case doesn’t compare different treatment approaches or doses of magnesium, so we can’t say whether other treatments might work better. Because this is such a rare condition, it’s hard to do large studies with many patients, which is why case reports are valuable for understanding rare diseases.

The Bottom Line

If a baby has unexplained seizures and blood tests show low calcium, doctors should check magnesium levels and consider genetic testing for TRPM6 mutations (moderate confidence based on this case and similar cases in medical literature). If this condition is diagnosed, daily magnesium supplements are the standard treatment and appear highly effective at stopping seizures and preventing complications (high confidence based on consistent outcomes across reported cases). Parents of affected children should work with a pediatric neurologist and metabolic specialist for ongoing monitoring and dose adjustments as the child grows.

Parents and doctors should care about this condition if a baby has seizures that don’t respond to typical seizure medications, or if blood tests show low calcium without an obvious cause. Genetic counselors should be involved if this condition is suspected, since both parents are carriers. This condition is rare, so most families won’t encounter it, but awareness helps doctors diagnose it quickly when it does occur. Babies with a family history of unexplained seizures or this specific genetic condition should be monitored closely.

Seizures typically start in early infancy (the first few months of life). Once magnesium supplementation begins, seizures usually stop within days to weeks. The baby in this case remained seizure-free at follow-up visits after starting treatment. Long-term magnesium supplementation appears to be needed for life, with doses adjusted as the child grows. Early diagnosis and treatment (within the first weeks of life) appear crucial for preventing permanent brain damage.

Want to Apply This Research?

  • If a child has been diagnosed with this condition, track daily magnesium supplement doses taken, any seizure activity (frequency and duration), and note any side effects from supplements. Record blood magnesium and calcium levels at each doctor visit to monitor whether current supplement doses are working.
  • Set daily reminders for magnesium supplement administration at the same time each day. Create a simple log to record whether the supplement was given and any symptoms observed. Schedule regular doctor visits (typically every 3-6 months) to check blood levels and adjust supplement doses as the child grows.
  • Maintain a long-term health record showing magnesium and calcium blood levels over time to ensure supplements are keeping levels in the healthy range. Track any seizure activity, developmental milestones, and medication changes. Share this information with all doctors involved in the child’s care, including pediatricians, neurologists, and metabolic specialists.

This case report describes one patient’s experience with a rare genetic condition. It is not medical advice and should not replace consultation with a qualified healthcare provider. If your baby has seizures or you suspect a metabolic disorder, seek immediate medical attention from a pediatrician or pediatric neurologist. Genetic testing and diagnosis should only be performed by qualified medical professionals. Any treatment decisions should be made in consultation with your child’s doctor. This information is for educational purposes only and does not constitute a diagnosis or treatment recommendation for your specific situation.