Symptoms & Urgent Warning Signs of MLS Syndrome

While every child with MLS syndrome is unique, certain reported symptoms and physical features are possible across the four main areas of the body the condition can affect: the eyes, skin, brain, and heart ^[1][2]. Because this is a multisystem condition with limited outcome data, screening is individualized rather than automatically required for every child. Your care team will monitor these systems closely, especially in the first few months of life ^[3].

Ocular (Eye) Symptoms

The eyes are one of the most frequently affected parts of the body in MLS. You may notice several different features:

• Microphthalmia: One or both eyes may be noticeably smaller than average ^[4]. (If the ocular tissue is completely absent or only rudimentary, the term anophthalmia is used instead).
• Sclerocornea: The cornea (the clear front window of the eye) may appear white or cloudy, sometimes blending in with the white part of the eye (the sclera) ^[4][5].

Dermatological (Skin) Symptoms

The “linear skin defects” that give the syndrome its name are usually present at birth.

• Appearance: These look like red, raw, or thin “streaks” of skin ^[6][7].
• Location: They are almost always found on the face and neck, though they occasionally appear on the ears or fingers ^[6][2].
• Healing: These defects are not typically painful once they heal. Over time, the redness fades, and the areas usually turn into thin, pale scars ^[6]. Unlike some other rare skin conditions, these streaks do not usually reappear later in life ^[7].

Neurological and Structural Symptoms

MLS can affect how the brain and skull develop. These differences are often found through imaging like an MRI or ultrasound ^[3].

• Agenesis of the Corpus Callosum: The band of tissue that connects the left and right sides of the brain may be thin or missing ^[8][9].
• Growth and Tone: Some infants may have slower growth (short stature) or differences in muscle tone ^[8][3].
• Seizures: While not present in everyone, some children with brain structure differences may develop seizures ^[8].

Cardiac (Heart) Symptoms

Heart issues are less common than eye or skin findings but can be more serious when they occur.

• Cardiomyopathy: A specific myocardial disorder called histiocytoid cardiomyopathy is sometimes linked to MLS, particularly when the NDUFB11 gene is involved ^[10][1]. This affects the heart’s muscle, which can cause important arrhythmias (rhythm problems) and sometimes pump dysfunction ^[10].
• Structural Defects: Some infants are born with small holes in the walls of the heart (septal defects) ^[1].

Emergency Red Flags: When to Seek Immediate Care

Because MLS can affect vital systems like the heart and airway, parents should follow a clear triage hierarchy.

What to do now:

• Call Emergency Services (911) for severe acute distress, breathing or neurologic emergencies.
• Call Your Care Team Urgently (Same-Day) for changes in the eyes, skin infection signs, or new mild feeding/breathing issues.

1. Emergency: Call Emergency Services (911)

• Breathing Issues: Cyanosis (skin or lips turning blue), severe work of breathing, or apnea (pausing in breathing) ^[11].
• Cardiac Distress: Unresponsiveness, severe lethargy, or sudden collapse ^[10].
• Seizure Emergencies: Call 911 for a first prolonged seizure, a seizure lasting about five minutes, repeated seizures without recovery in between, or a seizure with persistent color change/breathing difficulty. First Aid: Place the child on a safe, flat surface, turn them gently on their side to keep the airway clear, do NOT put anything in their mouth, and time the seizure ^[8].

2. Urgent: Same-Day Pediatric Ophthalmology or Doctor Visit

• Eye Concerns (Glaucoma Watch): Congenital glaucoma may be present from birth or recognized later ^[5]. Watch for a change from the child’s baseline: new or worsening corneal clouding, extreme light sensitivity (photophobia), severe tearing, apparent eye enlargement, or intense irritability/pain ^[5]. Do not attempt to measure eye pressure at home; prompt, professional assessment is required.
• Skin Infections: If the raw skin streaks on the face or neck become very swollen, warm, start draining pus, or if your baby develops a fever, seek prompt medical assessment. (Do not assume they need antibiotics until a clinician diagnoses a bacterial infection; a fever in a young infant requires careful evaluation) ^[6].
• Feeding Strain: “Noisy” breathing (stridor), frequent choking during every feeding, or “tiring out” and sweating heavily while eating, which can be signs of laryngeal defects, cleft palate, or cardiac strain ^[12][13][10].