Kinky hair, kinky vessels, and bladder diverticula in Menkes disease

Abnormal Development of Neural Stem Cell Niche in the Dentate Gyrus of Menkes Disease

Background and Objectives

Menkes disease (MNK) is a rare X-linked recessive disease, caused by mutations in the copper transporting ATP7A gene that is required for copper homeostasis. MNK patients experience various clinical symptoms including neurological defects that are closely related to the prognosis of MNK patients. Neural stem cells (NSCs) in the hippocampal dentate gyrus (DG) produce new neurons throughout life, and defects in DG neurogenesis are often correlated with cognitive and behavioral problems. However, neurodevelopmental defects in the DG during postnatal period in MNK have not been understood yet.

Methods and Results

Mottled-brindled (Mo^Br/y) mice (MNK mice) and littermate controls were used in this study. In vivo microCT imaging and immunohistochemistry results demonstrate that blood vasculatures in hippocampus are abnormally decreased in MNK mice. Furthermore, postnatal establishment of NSC population and their neurogenesis are severely compromised in the DG of MNK mice. In addition, in vitro analyses using hippocampal neurosphere culture followed by immunocytochemistry and immunoblotting suggest that neurogenesis from MNK NSCs is also significantly compromised, corresponding to defective neurogenic gene expression in MNK derived neurons.

Conclusions

Our study is the first reports demonstrating that improper expansion of the postnatal NSC population followed by significant reduction of neurogenesis may contribute to neurodevelopmental symptoms in MNK. In conclusion, our results provide new insight into early neurodevelopmental defects in MNK and emphasize the needs for early diagnosis and new therapeutic strategies in the postnatal central nerve system damage of MNK patients.

Lysyl oxidase-variant 2 (LOX-v2) colocalizes with promyelocytic leukemia-nuclear bodies in the nucleus

Lysyl oxidase-variant 2 (LOX-v2) is a novel variant of LOX that functions as an amine oxidase for the formation of collagen and elastin fibrils in the extracellular matrix (ECM). LOX-v2 lacks the N-terminal prepropeptide region of LOX but contains the C-terminal domains required for amine oxidase activity. To study the cellular localization of LOX-v2, we generated a recombinant construct of LOX-v2 with an epitope tag at the C-terminus and then transfected the recombinant construct into HEK293 cells. Upon ectopic expression, LOX-v2 showed much higher expression in the nucleus than in the cytoplasm. In coimmunofluorescence staining with subnuclear structures, LOX-v2 colocalized with the promyelocytic leukemia-nuclear bodies (PML-NBs). Further, the ectopic expression of LOX-v2 increased global SUMOylation in the nucleus. PML-NBs have been implicated in various cellular activities, including transcriptional regulation, DNA repair, cell cycle control, anti-viral response, and apoptosis. Our findings strongly indicate that LOX-v2 may be subject to different cellular processing from what LOX undergoes, playing a distinct functional role in the PML-NBs, beyond the cross-linking of the structural proteins.

The molecular mechanisms of copper metabolism and its roles in human diseases

Copper is an essential element in cells; it can act as either a recipient or a donor of electrons, participating in various reactions. However, an excess of copper ions in cells is detrimental as these copper ions can generate free radicals and increase oxidative stress. In multicellular organisms, copper metabolism involves uptake, distribution, sequestration, and excretion, at both the cellular and systemic levels. Mammalian enterocytes take in bioavailable copper ions from the diet in a Ctr1-dependent manner. After incorporation, cuprous ions are delivered to ATP7A, which pumps Cu⁺ from enterocytes into the blood. Copper ions arrive at the liver through the portal vein and are incorporated into hepatocytes by Ctr1. Then, Cu⁺ can be secreted into the bile or the blood via the Atox1/ATP7B/ceruloplasmin route. In the bloodstream, this micronutrient can reach peripheral tissues and is again incorporated by Ctr1. In peripheral tissue cells, cuprous ions are either sequestrated by molecules such as metallothioneins or targeted to utilization pathways by chaperons such as Atox1, Cox17, and CCS. Copper metabolism must be tightly controlled in order to achieve homeostasis and avoid disorders. A hereditary or acquired copper unbalance, including deficiency, overload, or misdistribution, may cause or aggravate certain diseases such as Menkes disease, Wilson disease, neurodegenerative diseases, anemia, metabolic syndrome, cardiovascular diseases, and cancer. A full understanding of copper metabolism and its roles in diseases underlies the identification of novel effective therapies for such diseases.

Osseous Metaplasia in a Bladder Diverticulum in a Patient with Mosaic Menkes Disease

Menkes disease, or Kinky Hair Syndrome, is a rare disorder of copper metabolism that causes fatal neurodegenerative disease in infancy. This X-linked disorder results from mutations in the ATP7A gene. Along with neurological decline, characteristic coarse appearance of the hair is seen. Urological issues are prevalent in this patient population, with bladder diverticula being the most common. Herein, we describe a unique male patient with genetic mosaicism and osseous metaplasia found in a ruptured bladder diverticulum.

Genetic Hair Disorders: A Review

Hair loss in early childhood represents a broad differential diagnosis which can be a diagnostic and therapeutic challenge for a physician. It is important to consider the diagnosis of a genetic hair disorder. Genetic hair disorders are a large group of inherited disorders, many of which are rare. Genetic hair abnormalities in children can be an isolated phenomenon or part of genetic syndromes. Hair changes may be a significant finding or even the initial presentation of a syndrome giving a clue to the diagnosis, such as Netherton syndrome and trichothiodystrophy. Detailed history including family history and physical examination of hair and other ectodermal structures such as nails, sweat glands, and sebaceous glands with the use of dermoscopic devices and biopsy all provide important clues to establish the correct diagnosis. Understanding the pathophysiology of genetic hair defects will allow for better comprehension of their treatment and prognosis. For example, in patients with an isolated hair defect, the main problem is aesthetic. In contrast, when the hair defect is associated with a syndrome, the prognosis will depend mainly on the associated condition. Treatment of many genetic hair disorders is focused on treating the primary cause and minimizing trauma to the hair.

Biallelic HEPHL1 variants impair ferroxidase activity and cause an abnormal hair phenotype

Maintenance of the correct redox status of iron is functionally important for critical biological processes. Multicopper ferroxidases play an important role in oxidizing ferrous iron, released from the cells, into ferric iron, which is subsequently distributed by transferrin. Two well-characterized ferroxidases, ceruloplasmin (CP) and hephaestin (HEPH) facilitate this reaction in different tissues. Recently, a novel ferroxidase, Hephaestin like 1 (HEPHL1), also known as zyklopen, was identified. Here we report a child with compound heterozygous mutations in HEPHL1 (NM_001098672) who presented with abnormal hair (pili torti and trichorrhexis nodosa) and cognitive dysfunction. The maternal missense mutation affected mRNA splicing, leading to skipping of exon 5 and causing an in-frame deletion of 85 amino acids (c.809_1063del; p.Leu271_ala355del). The paternal mutation (c.3176T>C; p.Met1059Thr) changed a highly conserved methionine that is part of a typical type I copper binding site in HEPHL1. We demonstrated that HEPHL1 has ferroxidase activity and that the patient's two mutations exhibited loss of this ferroxidase activity. Consistent with these findings, the patient's fibroblasts accumulated intracellular iron and exhibited reduced activity of the copper-dependent enzyme, lysyl oxidase. These results suggest that the patient's biallelic variants are loss-of-function mutations. Hence, we generated a Hephl1 knockout mouse model that was viable and had curly whiskers, consistent with the hair phenotype in our patient. These results enhance our understanding of the function of HEPHL1 and implicate altered ferroxidase activity in hair growth and hair disorders.

Lysyl oxidase family members in urological tumorigenesis and fibrosis

Lysyl oxidase (LOX) is an extracellular copper-dependent monoamine oxidase that catalyzes crosslinking of soluble collagen and elastin into insoluble, mature fibers. Lysyl oxidase-like proteins (LOXL), LOX isozymes with partial structural homology, exhibit similar catalytic activities. This review summarizes recent findings describing the roles of LOX family members in urological cancers and fibrosis. LOX/LOXL play key roles in extracellular matrix stability and integrity, which is essential for normal female pelvic floor function. LOX/LOXL inhibition may reverse kidney fibrosis and ischemic priapism. LOX and LOXL2 reportedly promote kidney carcinoma tumorigenesis, while LOX, LOXL1 and LOXL4 suppress bladder cancer growth. Multiple studies agree that the LOX propeptide may suppress tumor growth, but the role of LOX in prostate cancer remains controversial. Further studies are needed to clarify the exact effects and mechanism of LOX/LOXL on urological malignancies.

Neuroimaging in Menkes Disease

Menkes disease (MD) is a rare infantile onset neurodegenerative disorder due to mutations in the X linked ATP7A gene. These patients can present with failure to thrive, severe psychomotor retardation, seizures and hypopigmented hair, which is characteristic of this condition. A number of neuro-radiological findings have been reported in this condition. We report the spectrum of neuro-radiological findings in three affected boys being treated at our centre. We suggest that magnetic resonance imaging (MRI) and, in particular magnetic resonance angiography (MRA) when taken in the context of the clinical presentation may be helpful in making an early diagnosis of this devastating condition.

Neuroimaging Changes in Menkes Disease, Part 1

Menkes disease is a rare multisystem X-linked disorder of copper metabolism. Despite an early, severe, and progressive neurologic involvement, our knowledge of brain involvement remains unsatisfactory. The first part of this retrospective and review MR imaging study aims to define the frequency rate, timing, imaging features, and evolution of intracranial vascular and white matter changes. According to our analysis, striking but also poorly evolutive vascular abnormalities characterize the very early phases of disease. After the first months, myelination delay becomes evident, often in association with protean focal white matter lesions, some of which reveal an age-specific brain vulnerability. In later phases of the disease, concomitant progressive neurodegeneration might hinder the myelination progression. The currently enriched knowledge of neuroradiologic finding evolution provides valuable clues for early diagnosis, identifies possible MR imaging biomarkers of new treatment efficacy, and improves our comprehension of possible mechanisms of brain injury in Menkes disease.

Recurrent spontaneous subserosal hematoma of ileum causing intestinal obstruction in a patient with menkes disease: A case report

BACKGROUND

Menkes disease (MD) is a disorder of copper metabolism due to ATP7A gene mutation that leads to severe copper deficiency. Deformed blood vessels can be found in many parts of the body, and intracranial hematoma is generally reported.

METHODS

We report a Taiwanese boy with MD who had recurrent spontaneous subserosal hematoma of ileum presenting as intestinal obstruction, with the 2 episodes 23 months apart. The patient returned to the usual physical status after surgical removal of the hematoma.

RESULTS

The defective copper metabolism causes dysfunction of a plenty of copper-dependent enzymes, giving rise to unique kinky hair appearance, progressive neurodegeneration, and connective tissue abnormalities. To our knowledge, this is the first report on recurrent subserosal hemorrhage of intestine in MD.

CONCLUSION

Owing to the fragile structure of blood vessels, subserosal hematoma should be considered when patients with MD having intestinal obstruction.

Metabolic, endocrine, and other genetic disorders

Metabolic, endocrine, and genetic diseases of the brain include a very large array of disorders caused by a wide range of underlying abnormalities and involving a variety of brain structures. Often these disorders manifest as recognizable, though sometimes overlapping, patterns on neuroimaging studies that may enable a diagnosis based on imaging or may alternatively provide enough clues to direct further diagnostic evaluation. The diagnostic workup can include various biochemical laboratory or genetic studies. In this chapter, after a brief review of normal white-matter development, we will describe a variety of leukodystrophies resulting from metabolic disorders involving the brain, including mitochondrial and respiratory chain diseases. We will then describe various acidurias, urea cycle disorders, disorders related to copper and iron metabolism, and disorders of ganglioside and mucopolysaccharide metabolism. Lastly, various other hypomyelinating and dysmyelinating leukodystrophies, including vanishing white-matter disease, megalencephalic leukoencephalopathy with subcortical cysts, and oculocerebrorenal syndrome will be presented. In the following section on endocrine disorders, we will examine various disorders of the hypothalamic-pituitary axis, including developmental, inflammatory, and neoplastic diseases. Neonatal hypoglycemia will also be briefly reviewed. In the final section, we will review a few of the common genetic phakomatoses. Throughout the text, both imaging and brief clinical features of the various disorders will be discussed.

Menkes disease in Korea: ATP7A mutation and epilepsy phenotype

OBJECTIVE

Menkes disease (MD) is an X-linked recessive disorder characterized by progressive neuro-degeneration. There are few reports of epilepsy and electroencephalography (EEG) findings and few reports of MD patients in Korea. We explored MD genotypes and phenotypes, including epilepsy, in Korean patients.

PATIENTS AND METHODS

All patients diagnosed as MD in our hospital, seven males, were included in this study. Their medical records and EEG findings were reviewed retrospectively.

RESULTS

All male patients had developmental delay/regression with hypotonia, and the appearance of their hair and skin was characteristic of MD. A recurrent missense mutation was found in two patients. Two nonsense mutations and one gross deletion were also found. The five male patients with identified molecular defects experienced anticonvulsant-resistant seizures. EEGs in focal seizures usually revealed interictal focal epileptiform discharges over the posterior region without focal slowing. This was followed by modified hypsarrhythmia with less polymorphic background activity in spasms and anteriorly dominant diffuse slowing with generalized and multifocal epileptiform discharges in myoclonic or generalized tonic seizures. Two patients with the same G727R missense mutation both developed seizures that evolved with age but differed in severity.

CONCLUSIONS

G727R missense mutation may be relatively common in Korea, as in other countries. There was no clear correlation of genotype with phenotype, even in epilepsy and EEG abnormalities.

Hair curvature: a natural dialectic and review

Although hair forms (straight, curly, wavy, etc.) are present in apparently infinite variations, each fibre can be reduced to a finite sequence of tandem segments of just three types: straight, bent/curly, or twisted. Hair forms can thus be regarded as resulting from genetic pathways that induce, reverse or modulate these basic curvature modes. However, physical interconversions between twists and curls demonstrate that strict one-to-one correspondences between them and their genetic causes do not exist. Current hair-curvature theories do not distinguish between bending and twisting mechanisms. We here introduce a multiple papillary centres (MPC) model which is particularly suitable to explain twisting. The model combines previously known features of hair cross-sectional morphology with partially/completely separated dermal papillae within single follicles, and requires such papillae to induce differential growth rates of hair cortical material in their immediate neighbourhoods. The MPC model can further help to explain other, poorly understood, aspects of hair growth and morphology. Separate bending and twisting mechanisms would be preferentially affected at the major or minor ellipsoidal sides of fibres, respectively, and together they exhaust the possibilities for influencing hair-form phenotypes. As such they suggest dialectic for hair-curvature development. We define a natural-dialectic (ND) which could take advantage of speculative aspects of dialectic, but would verify its input data and results by experimental methods. We use this as a top-down approach to first define routes by which hair bending or twisting may be brought about and then review evidence in support of such routes. In particular we consider the wingless (Wnt) and mammalian target of rapamycin (mTOR) pathways as paradigm pathways for molecular hair bending and twisting mechanisms, respectively. In addition to the Wnt canonical pathway, the Wnt/Ca(2+) and planar cell polarity (PCP) pathways, and others, can explain many alternatives and specific variations of hair bending phenotypes. Mechanisms for hair papilla budding or its division by bisection or fission can explain MPC formation. Epithelial-to-mesenchymal (EMT) and mesenchymal-to-epithelial (MET) transitions, acting in collaboration with epithelial-mesenchymal communications are also considered as mechanisms affecting hair growth and its bending and twisting. These may be treated as sub-mechanisms of an overall development from neural-crest stem cell (NCSC) lineages to differentiated hair follicle (HF) cell types, thus providing a unified framework for hair growth and development.