Mosaicism for a dup(12)(q22q13) in a patient with hypomelanosis of Ito and asymmetry

[Leucoderma in children: Review of the literature]

BACKGROUND

Leucoderma is a frequent presenting complaint in children and it is sometimes difficult to make a definite diagnostic during the first consultation. The aim of this study is to analyse the diagnoses associated with leucoderma in children in order to propose a practical approach to their differential diagnosis.

MATERIAL AND METHODS

We performed a review of the literature using the keywords "leucoderma children review", "leucoderma Ito" and "nevus depigmentosus" in the Medline database. All relevant articles were included.

RESULTS

Four hundred and thirty-five articles were retrieved and 179 were analysed. A clinical approach was proposed in 6 articles and investigations in 15 articles.

DISCUSSION

Causal diagnosis of leucoderma may frequently be made on clinical grounds by determining the age of onset and distribution of lesions. Nevertheless, some situations require investigation. The literature is limited regarding clinical approaches and examinations in leucoderma. Herein, we present a systematic clinical and laboratory approach to the differential diagnosis of these skin disorders.

Hypomelanosis of Ito presenting with pediatric orthopedic issues: a case report

Introduction

Hypomelanosis of Ito was originally described as a purely cutaneous disease. Extracutaneous manifestations were described later, forming a neurocutaneous syndrome including skeletal, muscular, ocular and central nervous system symptoms.

Hypomelanosis of Ito is characterized by a depigmentation along the lines of Blaschko on the trunk and extremities in certain patterns.

The aim of this article was to report another case and give an overview of the related orthopedic symptoms that have been previously described. It was also our wish to contribute with recommendations for consideration with regard to bandages on eczematous rashes, especially on clubfeet.

Case presentation

A one-and-a-half-month-old boy of Caucasian background born with talipes equinovarus, or clubfoot, on his right foot presented with an eczematous rash after surgical correction and plaster bandaging.

Conclusions

It is the appearance of hypopigmentation, either alone or in combination with a congenital malformation, particularly central nervous system or musculoskeletal anomalies, which should form the basis of a presumptive diagnosis. This should then lead to further investigations and should always include skin biopsies and a test for chromosomal mosaicism.

We report the case of a boy with a clinical picture consisting of a depigmented skin pattern, mental retardation, pes cavus, talipes equinovarus, clinodactyly, eczema, inverted cilia of the eye, strabismus, reduced hearing, ventral hernia, glomerulonephritis, missing testicles, leg length discrepancy with scoliosis, back pain and a syrinx.

It is perhaps impossible to make any conclusions about extracutaneous symptoms. However, some symptoms such as retardation, cramps and seizures, delayed development and hypotonia cannot be ignored.

Because of the possibility of creating an undesirable and long postoperative period with complications, it is very important to have this diagnosis in mind when deciding to do surgery or not if there are signs of dermatological problems before surgery. In this case, it could also be good clinical practice to test the patient’s reaction to plaster or other bandages.

Incontinentia pigmenti and hypomelanosis of Ito

Incontinentia pigmenti (IP) is a rare X-linked dominant neurocutaneous disorder affecting ectodermal tissue: skin, eyes, central nervous system, hair, nails, and teeth. It is usually lethal for males in utero. The involved gene is NEMO, an essential component of the nuclear factor-kappa B (NF-κB) signaling pathway. Skin lesions are highly diagnostic, occurring in neonates, with a particular distribution on Blaschko lines. The severity of the disease is related to ocular and neurological impairment. The hallmark of ocular IP is retinal vasculopathy including peripheral retinal vascular nonperfusion, macular infarction and neovascularization, and preretinal neovascularization. CNS involvement consists of seizures, mental retardation, hemiparesis, spasticity, microcephaly, cerebellar ataxia, and coma. It often occurs in neonates. Some patients have persistent pharmacoresistant seizures throughout life. MRI findings consist essentially in: white-matter lesions; scattered cortical neuronal necrosis; multiple cerebral infarctions; cerebral atrophy, hypoplasia of the corpus callosum, encephalomalacia and neuronal heterotopia. A predominant role of vascular occlusive phenomena in small vessels is highly suspected. In fact several intricate mechanisms could be discussed: vascular, inflammatory, developmental mechanisms. Their role and predictive factors of IP CNS involvement in neonatal IP need to be better understood to identify effective innovative therapies. Hypomelanosis of Ito can occur in the neonate, infancy, or childhood, be isolated or diffuse, often following the Blaschko lines, and can fade in childhood or adulthood. It is due to reduced melanin in the epidermis. Eye, central nervous (mental retardation, epilepsy, language disabilities, motor system dysfunction, psychiatric symptoms including autism - with frequent cortical malformations including hemimegalencephaly and white matter involvement), and musculoskeletal systems can also be affected. Mosaicism with various chromosomal rearrangements has been reported.

Pure direct duplication (12)(q24.1 → q24.2) in a child with Marcus Gunn phenomenon and multiple congenital anomalies

Partial trisomy of the region 12q24.1-->q24.2 is rare and usually associated with other rearrangements. We report on the clinical and cytogenetic findings in a girl with a pure de novo direct duplication dup(12)(q24.1-->q24.2). She had developmental and growth retardation, facial dysmorphism with upslanting palpebral fissures, wide downturned mouth, short neck, and Marcus Gunn phenomenon. She also had single transverse creases, hypoplasia of the corpus callosum, and cardiac malformations consisting of a bicuspid aortic valve, multiple ventricular septal defects, and kinking of the aorta. The size of the duplication was characterized by molecular cytogenetics and comparative genomic hybridization (CGH) to be 11.5 Mb in size and extended from the BAC probe RP11-256L11 loci (108.2 Mb) +/- 1 Mb to the BAC probe RP11-665J20 loci (119.7 Mb) +/- 1 Mb. No such pure 12q24 duplication was detected out of the 23 patients reported in the literature with duplications in 12q region. Comparison with these reported 12q trisomies suggests the duplication dup(12)(q24.1-->q24.2) is associated with a recognizable phenotype consisting of characteristic facial dysmorphism, growth retardation, and cardiac malformation.

Abnormal pigmentation in hypomelanosis of Ito and pigmentary mosaicism: the role of pigmentary genes

There is increasing evidence that hypomelanosis of Ito and related disorders such as linear and whorled naevoid hypermelanosis are due to mosaicism for a variety of chromosomal abnormalities. This group of disorders is better termed 'pigmentary mosaicism'. In this review we explain how disparate chromosomal abnormalities might manifest as a common pigmentary phenotype. In particular, we provide evidence supporting the hypothesis that the chromosomal abnormalities reported in these disorders specifically disrupt expression or function of pigmentary genes.

New concepts to improve resolution and sensitivity of molecular cytogenetic diagnostics by multicolor fluorescence in situ hybridization

BACKGROUND

Routine application of multicolor fluorescence in situ hybridization (M-FISH) technology for molecular cytogenetic diagnostics has been hampered by several technical limitations. First, when using chromosome-specific painting probes, there is a limit in cytogenetic resolution of approximately 2-3 Mb, which can mask hidden structural abnormalities that have a significant clinical effect. Second, using whole chromosome painting probes, intrachromosomal rearrangements cannot be detected and the exact localization of breakpoints is often not possible.

METHODS

We suggest the use of multiplex-labeled region or locus- specific probes in combination with an optimal probe design to improve the sensitivity and resolution of the M-FISH technology. To allow the application of this assay in routine diagnostics, we developed a multipurpose image analysis system.

RESULTS

goldFISH was applied to the study of cryptic translocations in mental retardation patients and to the study of high-resolution breakpoint mapping in non-small cell lung cancer patients. For an individual with mental retardation, who had an apparently normal karyotype by G-banding, we detected an unbalanced translocation involving chromosomes 2 and 7.

CONCLUSIONS

In combination with optimally designed probe kits, goldFISH overcomes most of the present limitations of the M-FISH technology and results in virtually 100% reliability for detecting interchromosomal and intrachromosomal rearrangements.