British singer Jesy Nelson has shared that her eight-month-old twin daughters, Ocean Jade and Story Monroe born prematurely in May 2025 have been diagnosed with Spinal Muscular Atrophy (SMA) Type 1, a rare and serious muscle-weakening disorder, according to her recent social media announcement.
Nelson explained that the girls initially showed limited movement in their legs and feeding difficulties, which were at first attributed to prematurity. However, after several months of medical evaluations, physicians confirmed the diagnosis of SMA Type 1, the most severe and early-onset form of the disease.
Spinal Muscular Atrophy is a genetic neuromuscular condition characterized by the progressive loss of motor neurons nerve cells in the spinal cord that control muscle movement. When these neurons are lost, muscles weaken and waste away (atrophy), affecting voluntary movements such as rolling, sitting, walking, swallowing and breathing.
SMA is caused most commonly by mutations in the SMN1 gene, which normally produces the survival motor neuron (SMN) protein essential for motor neuron function. When SMN protein levels are deficient, motor neurons degenerate, leading to muscle weakness. Variability in symptom severity is influenced by the number of copies of a related gene, SMN2, which can partially compensate for the loss of SMN1 function.
SMA is classified into several types, mainly based on age of symptom onset and severity of muscle weakness. All types are genetic, but their clinical presentations and prognoses differ:
Type 0: A very rare form detectable before birth, with severe symptoms at birth; infants often have decreased fetal movement and may not survive beyond a few months.
Type 1 (Infantile Onset/Werdnig-Hoffmann disease): Symptoms appear before six months of age. Babies typically have generalized muscle weakness, poor head control, difficulty swallowing and breathing, and do not reach major motor milestones such as sitting independently. Without intervention, Type 1 SMA can be life-threatening in infancy.
Type 2: Onset usually occurs between 6 and 18 months; children may sit but generally do not stand or walk independently. Respiratory and feeding challenges can also occur.
Type 3 (Kugelberg–Welander disease): Symptoms begin after 18 months and continue into adulthood; individuals may initially walk but often develop progressive weakness affecting mobility.
Type 4: A late-onset and generally milder form appearing in adulthood, with slower progression and less severe impairment.
The earlier the onset, the more severe the muscle weakness tends to be. SMA Type 1 is the most common and severe, often presenting in infancy with rapid progression if not managed promptly.
In SMA Type 1, signs typically appear before babies are six months old and include poor muscle tone, weakness in the limbs and trunk, difficulties with feeding and swallowing, and challenges maintaining respiratory function. Without treatment, infants with Type 1 SMA historically faced severe disability and short life expectancy, often not surviving past early childhood.
Advances in early diagnosis and disease-modifying treatments—including gene therapy and SMN-enhancing medications—can improve outcomes and slow disease progression if initiated early.
Nelson, 34, disclosed the diagnosis via a video posted on social media in early January 2026, stating that clinicians informed her the girls may never walk or regain full neck strength due to the severity of their condition.
She described the emotional toll of the diagnosis and highlighted the ongoing need for respiratory support and specialized care. Despite the challenges, she expressed gratitude for the treatment her daughters have begun, noting that even in severe cases, prompt intervention is critical for improving survival and developmental potential.
SMA affects voluntary muscles—those used to control movement—while typically sparing involuntary muscles like those controlling the heart or digestion. As a result, individuals with SMA may retain some bodily functions even as motor abilities decline.
Because the condition is inherited and genetic, families with a child diagnosed with SMA are often referred to genetic counselling to understand recurrence risks and implications for other family members. +
Reference
1. Muscular Dystrophy Association, “Types of Spinal Muscular Atrophy (SMA),” accessed 5th January 2026, Muscular Dystrophy Association, https://www.mda.org/disease/spinal-muscular-atrophy/types.
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