An incontinentia pigmenti family with deletion in both NEMO gene and pseudogene DeltaNEMO

OBJECTIVE: To detect the genomic deletion mutation in the NEMO gene of a family with incontinentia pigmenti (IP; MIM 308310). METHODS: A pedigree of IP was investigated. By using long PCR, the Delta4-10 deletion in NEMO gene was tested with specific primers In2/JF3R, and Delta4-10 deletion in pseudogene DeltaNEMO was investigated with primers Rev-2/JF3R. NEMO gene of 80 normal controls was also tested. RESULTS: The deletion of exons 4-10 in both NEMO gene and the pseudogene DeltaNEMO was detected in all the patients in the family, but was not found in the normal individuals in this IP family and 80 unrelated controls. CONCLUSION:The study showed that the family with IP, which showed anticipation, was caused by NEMODelta4-10 deletion in the NEMO gene. Long PCR analysis is proven to be an efficient tool for identification of NEMO rearrangements. It could provide useful information for the genetic counseling of the family involved.     

一个色素失禁症家系的NEMO基因和假基因△NEMO缺失突变分析

目的 用长链聚合酶链反应进行检测家族性色素失禁症(incontinentia pigmenti,IP)患者的NEMO基因的缺失突变.方法 收集一色素失禁症家系的临床资料,选取NEMO基因特异引物In2/ff3R和假基因△NEMO的特异引物Rev-2/JF3R,采用长链聚合酶链反应对家系内成员NEMO基因和假基因△NEMO的缺失位点进行检测,同时对80名无血缘关系健康对照者的该位点进行同样检测.结果 所有患者皆有NEMO基因和假基因△NEMO基因共有序列NEMO△4-10缺失,而在家系内非患者以及80名正常对照者中均未发现NEMO基因和假基因△NEMO的共有序列NEMO4△-10缺失.结论 该家系为一个典型遗传早现现象的IP家系,NEMO基因和△NEMO的缺失突变导致其发病.长链PCR扩增技术可用于检测NEMO基因的缺失突变,对于遗传咨询具有一定的应用价值.     

Gonadal mosaicism for incontinentia pigmenti in a healthy male.

Incontinentia pigmenti (IP) is a genodermatosis that segregates as an X linked dominant trait with male lethality. The disease has been linked to Xq28 in a number of studies. A few affected males have been documented, most of whom have a 47,XXY karyotype. We report a family with two paternally related half sisters, each affected with IP. The father is healthy, clinically normal, and has a 46,XY normal male karyotype. Linkage analysis of 12 polymorphic markers (two X linked and 10 autosomal) confirms paternity. X inactivation studies with the human androgen receptor (HUMARA) indicate that the paternal X chromosome is inactivated preferentially in each girl, implying that this chromosome carries the IP mutation, and that the father is a gonadal mosaic for the IP mutation.     

Neurological findings in incontinentia pigmenti; a review

Incontinentia Pigmenti is a rare X-linked multisystem disorder with well described and pathognomonic skin manifestations. Neurological manifestations are found in 30% of IP patients, forming one of the major causes of morbidity and mortality of the condition. In this review, clinical and brain imaging data of 45 IP patients with a neurological phenotype are reviewed. Several clinical presentations could be identified, comprising seizures, infantile encephalopathy, acute disseminated encephalomyelitis and ischemic stroke. Most neurological features presented during the neonatal period. No patients presented during adolescence or at adult age. Seizures of different type are reported in about 20% of the patients at young age and seem to correlate with the degree of cerebrovascular damage. Brain MRI findings include periventricular and subcortical white matter disease, haemorrhagic changes, corpus callosum hypoplasia, cerebral atrophy and cerebellar hypoplasia. Ocular findings comprise a range of retinal vascular changes and optic atrophy, but also developmental defects like microphthalmia and cataract. Most findings may reflect changes following brain injury. Both (ischemic) vascular and inflammatory components may play a role in the cerebral and ocular phenotype. However, a role of disturbed apoptosis during development may also be a contributing factor.     

Unilateral acheiria and fatal primary pulmonary hypertension in a girl with incontinentia pigmenti

We describe a newborn girl with incontinentia pigmenti (IP, MIM308300), unilateral acheiria, and fatal primary pulmonary hypertension. Limb deficiency has not been described previously in IP and pulmonary hypertension only on two previous occasions. A review of the cause of IP shows that these rare manifestations may not be unexpected, given the many roles of the underlying gene product.     

Partial sweat gland aplasia in incontinentia pigmenti Bloch-Sulzberger

Dermatoglyphic investigation of palm prints in patients with Incontinentia pigmenti revealed in five of eight cases a partial ridge dissociation with lack of sweat gland pores. This disease can, therefore, be accepted as a second X-linked anhidrotic ectodermal dysplasia, which, however, is only segregated in the female.     

A successful treatment of tadalafil in incontinentia pigmenti with pulmonary hypertension

We describe a female infant with incontinentia pigmenti complicated by severe pulmonary arterial hypertension that was markedly improved by tadalafil administration. The infant was referred to our institution because of neonatal seizures and generalized skin rash at the age of 1 day. She was diagnosed with incontinentia pigmenti on skin biopsy findings. In addition to incontinentia pigmenti, she had pulmonary arterial hypertension without structural heart disease. The pulmonary hypertension rapidly worsened at the age of 2 months and was confirmed by cardiac catheterization. The pulmonary artery pressure was equal to systemic pressure but it decreased in response to nitric oxide inhalation. We, therefore, initiated treatment with tadalafil of 1 mg/kg/day. The follow-up cardiac catheterization performed at 9 months revealed dramatic improvement in the pulmonary artery pressure. An IKBKG mutation with deletion of exons 4–10 was detected in the blood of both the patient and her mother. Our experience indicates that tadalafil may be beneficial in treating pulmonary arterial hypertension associated with incontinentia pigmenti.     

Interaction of incontinentia pigmenti and factor VIII mutations in a female with biased X inactivation, resulting in haemophilia.

We report a female infant born to a mother with incontinentia pigmenti (IP) and a father with haemophilia A, who manifests both disorders. Analysis of peripheral blood DNA from the infant, her mother, and two female relatives with IP showed a highly skewed pattern of X inactivation. Random patterns were observed in the infant's two sisters, who do not have IP and have normal carrier activity of factor VIII. Preferential inactivation of the X chromosome bearing the IP mutation, probably by negative selection, appears to have unmasked the factor VIII mutation on the infant's other X chromosome. This illustrates an unusual mechanism for the manifestation of an X linked disease in a heterozygous female.     

Unstable pre-mutation may explain mosaic disease expression of incontinentia pigmenti in males

Mosiac skin lesions following the lines of Blaschko are found in boys affected by incontinentia pigmenti (IP). For an X-linked gene defect, this is rather surprising. To explain the mosaic disease expression of IP in males, we propose that the disease is caused by an unstable pre-mutation, which normally remains silent in males during early embryogenesis. Occasionally “silencing” is incomplete and gives rise to clinical manifest IP reflecting a mosaic state of alleles with the full and the pre-mutation in the same patient. This model can account for mother-to-son transmission of IP and for disparate phenotypes in monozygotic female twins. © 1994 Wiley-Liss, Inc.     

Recent progress in the genetics of incontinentia pigmenti (Bloch-Sulzberger syndrome)

Incontinentia pigmenti (IP) is a rare disorder which affects organs and tissues of ectodermal and mesodermal origin. It is characterized by swirled patterns of hyperpigmentation. In some cases, the condition is also associated with malformations of the teeth, nails, skeleton, hair, eyes, and the central nervous system. The disorder is inherited as an X-linked dominant trait and mostly affects females. However, there have been several cases of IP in males that survived to birth. While IP in females could be caused by a skewed pattern of X-inactivation, three mechanisms: namely, the half-chromatid hypothesis, unstable pre-mutation, and a higher rate of de-novo germline mutations, have been proposed to explain the survival of affected male patients. Cytogenetic studies in several sporadic cases with signs similar to IP exhibited an X/autosomal translocation involving a breakpoint at Xp11, suggesting a gene locus on Xp11 (IP1). Li Received: August 15, 2000 / Accepted: August 30, 2000     

Male cases of incontinentia pigmenti: Case report and review

Male patients with Bloch-Sulzberger incontinentia pigmenti (IP type II) are rare and more severely affected than their female counterparts, with a significant occurrence of sex chromosome aneuploidy. This document introduces a new male IP type II patient and reviews 48 males reported with IP. Twenty-eight of the 49 patients meet current criteria for diagnosis of IP type II. The phenotype is variable and the incidence of documented developmental delay is 25%. Five patients had Klinefelter syndrome (47,XXY). Most patients were reported prior to 1961 when chromosome analysis was not available. Biopsy and laboratory reports considered to be “consistent with” the diagnosis of IP were seen in patients meeting criteria as well as those who would not currently be given the diagnosis. The histologic findings considered diagnostic are varied. This variability may be accounted for by differences in stage of disease, biopsy site, histologic technique, and reporting style. Conversely, this may indicate that the diagnostic weight given to the biopsy should be reconsidered. Eosinophilia was not a consistent finding. Overall, differences in reporting, ascertainment, and length of follow-up lead to difficulty in interpreting or predicting the natural history of males with IP type II. Based on the existing literature, they appear to have a higher rate of mental retardation than the general population, but there does not appear to be a correlation between severity of physical and mental involvement. The presence of sex chromosome aneuploidy documented in the more recent cases emphasizes the need for chromosome analysis in any male patient suspected of IP type II. Am. J. Med. Genet. 77:201–218, 1998. © 1998 Wiley-Liss, Inc.     

Incontinentia pigmenti: XXY male with a family history

We report on the case of a male who from the start of life displayed vesicular lesions; on the trunk these were clustered and on the limbs they adopted a linear configuration. After biopsy of one such lesion, the histopathological study was compatible with a diagnosis of incontinentia pigmenti (IP). In the following months, hyperkeratotic lesions appeared which later became pigmented. The mother and other female members of the family also showed different degrees of alteration related to the same disease. The karyotype study showed the existence of 47,XXY (Klinefelter syndrome). The exceptional nature of this case is that although it is the third case reported in the literature of a male affected by incontinentia pigmenti with a previous family history, it is the only one combining this characteristic with the presence of a 47,XXY karyotype.     

A recurrent deletion in the ubiquitously expressed NEMO (IKK-gamma) gene accounts for the vast majority of incontinentia pigmenti mutations

Incontinentia pigmenti (IP) is an X-linked dominant disorder characterized by abnormal skin pigmentation, retinal detachment, anodontia, alopecia, nail dystrophy and central nervous system defects. This disorder segregates as a male lethal disorder and causes skewed X-inactivation in female patients. IP is caused by mutations in a gene called NEMO, which encodes a regulatory component of the IkappaB kinase complex required to activate the NF-kappaB pathway. Here we report the identification of 277 mutations in 357 unrelated IP patients. An identical genomic deletion within NEMO accounted for 90% of the identified mutations. The remaining mutations were small duplications, substitutions and deletions. Nearly all NEMO mutations caused frameshift and premature protein truncation, which are predicted to eliminate NEMO function and cause cell lethality. Examination of families transmitting the recurrent deletion revealed that the rearrangement occurred in the paternal germline in most cases, indicating that it arises predominantly by intrachromosomal misalignment during meiosis. Expression analysis of human and mouse NEMO/Nemo showed that the gene becomes active early during embryogenesis and is expressed ubiquitously. These data confirm the involvement of NEMO in IP and will help elucidate the mechanism underlying the manifestation of this disorder and the in vivo function of NEMO. Based on these and other recent findings, we propose a model to explain the pathogenesis of this complex disorder.