Simple test that can check for SMA Type 1 as former Little Mix star Jesy Nelson reveals signs of twin girls' diagnosis

A quick and simple test may now offer families early insight into SMA Type 1, a serious genetic condition, potentially transforming diagnosis and care.

Attention to SMA Type 1 has increased recently, after Jesy Nelson shared that her twins were diagnosed with the genetic condition, highlighting the importance of early detection and support.

The ex-Little Mix singer welcomed her daughters Ocean Jade and Story Monroe Nelson-Foster in May 2025.

Nelson had a difficult pregnancy, as the 34-year-old was diagnosed with something called Twin-to-Twin Transfusion syndrome (TTTS) and had to undergo surgery.

TTTS is 'rare disorder that affects identical twin pregnancies' and happens when two babies share a placenta in the womb. It causes uneven blood flow between the two babies and puts the twins at risk for early delivery, neurological damage, heart damage and can even be fatal.

The babies were born prematurely and spent around four weeks in the NICU.

On Sunday (Jan. 4), Nelson posted an emotional video on social media in which she revealed that her daughters had been diagnosed with SMA Type 1.

Nelson said that her mom had noticed that the girls weren't moving their legs very much. This sparked a series of hospital appointments and tests, which lead to the Little Mix alum being told her daughters have SMA.

"After the most gruelling three to four months and endless appointments, the girls have been diagnosed with a severe disease called SMA type one," she shared.

"It stands for Spinal Muscle Atrophy which affects every muscle in the body from legs, arms, swallowing."

The genetic condition causes worsening muscle weakness, Cleveland Clinic explains.

"Over time, it kills the muscles in the body. If it’s not treated in time, your baby's life expectancy will not make it past the age of two,” Nelson added.

"Once the girls got treated, it was a very rapid process. Time is of the essence with this disease.

"When they assessed the girls at Great Ormond Street, we were told they were never going to be able to walk. They would probably never regain their next strength. They will be disabled. The best thing we can do right now is to get them treatment and hope for the best."

There is a genetic test that can diagnose infants with the condition. Early detection is very important and for babies, the test is done with a tiny heel prick, similar to routine newborn screenings. The blood is analyzed in a lab for changes to the SMN1 gene which causes SMA Type 1.

Little Mix star Jesy Nelson gave birth to twins in May 2025 (jesynelson/Instagram)

Detecting the condition early can be life-changing, as treatments are most effective before symptoms appear.

Newborn screening for SMA, including SMA Type 1, is now part of standard newborn screening in the United States.

In 2018, SMA was added to the U.S. Recommended Uniformed Screening Panel (RUSP). As of 2024, all 50 U.S. states screen for SMA, nonprofit organization Cure SMA reports.

Routine newborn screenings for SMA is far more widespread in the United States than in the UK and much of Europe. In the UK, the condition is not yet part of the standard NHS newborn blood‑spot screening panel, SMAUK explains, the UK's leading charity supporting individuals and families affected by Spinal Muscular Atrophy.

When babies in the UK are five days old, the NHS performs a routine blood‑spot test through a tiny heel prick to check for nine rare but serious conditions, however, SMA is not part of the list.

SMAUK states that SMA is among the leading genetic causes of infant death in the UK. Without treatment, around nine out of 10 babies born with SMA Type 1 will either die before their second birthday or need lifelong ventilation support.

The UK National Screening Committee (UK NSC) is actively reviewing it, with pilot studies underway as of 2026.