Infant gets SMA diagnosis along with Down syndrome: Case study
Coexistence of two genetic disorders presents challenges
An infant was diagnosed with Down syndrome coexisting with spinal muscular atrophy (SMA) type 1, a case study reported.
“The coexistence of [Down syndrome] and SMA poses unique challenges due to overlapping clinical features,” the researchers wrote in the case study, “A Rare Genetic Intersection: Down Syndrome With Coexisting Spinal Muscular Atrophy,” which was published in Cureus.
Down syndrome is a genetic disorder caused by a random error in cell division that results in an extra partial or full copy of chromosome 21. It’s marked by cognitive and behavioral problems and distinct physical features, including a flattened face, almond-shaped eyes that slant up, and a tongue that tends to stick out of the mouth.
SMA is a genetic disease caused by inherited mutations in the SMN1 gene, leading to the degeneration of motor neurons, the nerve cells that control muscle movement. This results in muscle atrophy (shrinkage), weakness, and eventual paralysis. Unlike Down syndrome, SMA is not usually accompanied by cognitive impairment.
A team at the Al Qassimi Women’s and Children’s Hospital in the United Arab Emirates described the case of an infant with Down syndrome coexisting with SMA.
Down syndrome, SMA diagnosis
The three-month-old infant arrived at the hospital with breathing difficulties and low oxygen levels. She was born via vaginal delivery with a low birth weight, 2.08 kg (4.6 pounds) after a normal gestation to consanguineous (related) parents.
The neonatal period was mostly uneventful, with the exception of moderate patent ductus arteriosus (PDA), or an opening between the two major blood vessels leading from the heart. The mother also said there had been feeding issues since birth. No family history of any genetic disorder was noted.
On initial examination, doctors saw the child had a flattened nasal bridge, up-slanting eyes, and low-set ears, consistent with Down syndrome. She also had low muscle tone, breathing distress, and a failure to thrive. She was initially given non-invasive breathing support and antibiotics for aspiration pneumonia, a lung infection caused by inhaling things other than air.
However, she continued to deteriorate. She was intubated with invasive breathing support for more than one month, and attempts to remove the breathing tubes failed. As a result, further tests, including genetic testing, were ordered, and the PDA was fixed to support breathing.
Because Down syndrome is known to be associated with immunodeficiency, the child was started on antiviral, antifungal, and antibacterial medications. Her condition improved, and she was discharged.
Genetic studies confirmed Down syndrome while ruling out immunodeficiency. Unexpectedly, she also showed a hallmark mutation in the SMN1 gene, which was confirmed with a second genetic test.
An SMA diagnosis followed.
The girl was diagnosed with Down syndrome coexisting with SMA type 1 and was managed by a multidisciplinary team including neurologists, pulmonologists, geneticists, and rehabilitation specialists.
“This case report highlights the uncommon co-occurrence of two distinct genetic conditions in a single patient,” the researchers wrote. “Further research is warranted to explore the genetic and clinical interactions for such conditions, for potential future therapeutic approaches and improving patient outcomes,” they wrote.
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