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Microphthalmia with linear skin defects syndrome
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Condition

Microphthalmia with linear skin defects syndrome

Microphthalmia with linear skin defects syndrome is a rare genetic disorder primarily affecting females, characterized by small or poorly developed eyes and distinctive linear skin markings.

Overview

Microphthalmia with linear skin defects syndrome is a disorder that mainly affects females. In people with this condition, one or both eyes may be very small or poorly developed (microphthalmia). Affected individuals also typically have unusual linear skin markings on the head and neck. These markings follow the paths along which cells migrate as the skin develops before birth (lines of Blaschko). The skin defects generally improve over time and leave variable degrees of scarring.

Symptoms

The signs and symptoms of this condition vary widely, even among affected individuals within the same family. In addition to characteristic eye problems and skin markings, the condition can cause:

  • Abnormalities in the brain, heart, and diaphragm
  • A hole in the muscle that separates the abdomen from the chest cavity (diaphragm)
  • Short stature
  • Nail dystrophy (fingernails and toenails that do not grow normally)

Causes

Mutations in the HCCS gene or a deletion of genetic material on the X chromosome that includes the HCCS gene cause this syndrome. The HCCS gene carries instructions for producing an enzyme called holocytochrome c-type synthase, which is active in the mitochondria—the energy-producing centers within cells.

Within the mitochondria, this enzyme helps produce cytochrome c, which is involved in generating adenosine triphosphate (ATP), the cell's main energy source, and plays a role in the self-destruction of cells (apoptosis). A lack of functional enzyme can damage cells by impairing energy generation and preventing necessary apoptosis, leading to inflammation and cell damage during early development.

Inheritance

This condition is inherited in an X-linked dominant pattern. In females, a mutation in one of the two copies of the gene in each cell is sufficient to cause the disorder. In males, who have only one X chromosome, a total loss of the enzyme is typically lethal very early in development, meaning almost no males are born with the syndrome. Most cases occur in people with no family history, resulting from new mutations or deletions during the formation of reproductive cells or early fetal development.

Frequently Asked Questions

Diagnosis relies on molecular testing. A targeted next‑generation sequencing panel or whole‑exome sequencing that includes the HCCS gene can identify pathogenic variants or a contiguous X‑chromosome deletion encompassing HCCS. In some labs, a chromosomal microarray is used to detect larger deletions. Confirmation is usually followed by ophthalmologic imaging (ultrasound or MRI) to document eye structure and by cardiac/abdominal ultrasound to screen for associated anomalies.
Because the syndrome can involve the heart, diaphragm, brain, and growth, a baseline echocardiogram, brain MRI, and abdominal ultrasound are advised within the first year of life. Follow‑up cardiac imaging is recommended every 1–2 years, respiratory assessment for diaphragmatic hernia if symptoms arise, and growth charts with endocrine evaluation for short stature. Annual dermatology review helps track scar formation, and developmental assessments should be performed to detect any neurocognitive issues early.
Look for markedly small or absent eyes (microphthalmia) together with linear, streak‑like hypopigmented or hyperpigmented skin lesions that follow the Blaschko lines on the scalp, face, or neck. The combination of ocular under‑development and characteristic skin patterns, especially in a female infant, should raise suspicion and trigger genetic evaluation.
Management is multidisciplinary. If a microphthalmic eye is present, early referral to a pediatric ophthalmologist is essential. Options may include prosthetic eye fitting, surgical enlargement (enucleation with orbital implant) for cosmetic symmetry, and low‑vision aids if any residual vision exists. In cases where one eye is relatively larger, amblyopia therapy may help preserve function, but severe microphthalmia often limits visual potential.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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