IP is a rare X-linked dominant disorder. About 700 to 1000 cases have been reported worldwide (about 1 in 50,000 live births); white infants are most commonly affected. In a review of 653 patients, more than half had a family history of the condition.1 Our patient's mother was also affected. IP usually appears within the first 2 weeks of life. The severity and expression of the disorder are highly variable, even among patients within the same family.1,3 The condition is characterized by anomalies of the organs and tissues derived from the ectoderm and mesoderm and may affect the skin, hair, nails, teeth, eyes, and CNS1,2:
FigureA 9-month-old African American girl presented with whorls of hyperpigmentation in a swirled pattern on the extremities and trunk. This condition began at birth as a linear rash of vesicles and pustules: in a female infant, this pattern is diagnostic of incontinentia pigmenti (IP)-also known as Bloch-Sulzberger syndrome. The characteristic hyperpigmentation is the result of excessive deposits of melanin in the superficial dermis.
1,2
IP is a rare X-linked dominant disorder. About 700 to 1000 cases have been reported worldwide (about 1 in 50,000 live births); white infants are most commonly affected. In a review of 653 patients, more than half had a family history of the condition.1 Our patient's mother was also affected. IP usually appears within the first 2 weeks of life. The severity and expression of the disorder are highly variable, even among patients within the same family.1,3 The condition is characterized by anomalies of the organs and tissues derived from the ectoderm and mesoderm and may affect the skin, hair, nails, teeth, eyes, and CNS1,2:
Transmission of IP is caused by mutations in the nuclear factor-kB essential modulator (NEMO) gene located at chromosome Xq28.1,3 This gene controls inflammatory responses and cellular apoptosis and is also found in anhidrotic ectodermal dysplasia with immune deficiency.1 A deletion of exons 1 to 4 is identified in 85% of patients.1,3 IP is almost always lethal for the hemizygous male fetus in the first trimester; therefore, 97% of patients with this disorder are female.2,3 Females with IP mutations survive because of heterozygosity at the NEMO locus and skewed X inactivation, where the mutant X chromosome is preferentially inactivated.5 Males with IP usually have Klinefelter syndrome (47,XXY), in which the XXY genotype allows survival.1,2 Interestingly, the severity of IP is not related to the type of mutation.6
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The diagnosis of IP is based on the clinical history and examination. Skin biopsies can be helpful in unusual presentations; each stage is characterized by certain histopathological findings.5 Histological features that reflect keratinocyte apoptosis can help clarify an IP diagnosis and may be included as a major criterion for diagnosing IP.6 Genetic counseling should involve both the patient and relatives. When cases are in doubt, DNA studies can help ascertain or rule out the diagnosis.
Patients with IP in the early stages may require standard wound care to decrease the likelihood of secondary infections associated with blister formation, especially with the emergence of methicillin-resistant Staphylococcus aureus.4,5 The severity and outcome of IP is directly related to ocular and neurological impairment. A complete neurological examination and regular visits to an ophthalmologist and dentist are recommended to achieve optimal outcomes.
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