Is It a Pathogenic ATP7A Variation and Is It Menkes Disease?

Menkes disease is a very rare X-linked copper metabolism disorder that results from an ATP7A gene mutation. With the advent of subcutaneous copper-histidine therapy, the early diagnosis of Menkes disease becomes of utmost importance for patients' prognosis. In the present study, the clinical characteristics of 12 Korean patients with Menkes disease (11 males and 1 female from 11 unrelated families) were described along with the mutation spectrum. Only 2 male patients were diagnosed in the neonatal period, and the other male patients were diagnosed at age 4.3 ± 1.9 months. The presenting signs included depigmented kinky hair, neurologic deficits, and hypotonia. Serum copper and ceruloplasmin levels were markedly decreased. Intracranial vessels were dilated with tortuosity and accompanied by regional cerebral infarctions, even at an early age. Of note, the female patient was diagnosed at age 18 months, during the evaluation for developmental delay, by characteristic MRA findings, biochemical profiles, and genetic evaluation. A total of 11 ATP7A mutations were identified, including five previously unreported mutations. Most mutations were truncated (except 1 missense mutation), including 3 frameshift, 2 nonsense, 3 large deletion, and 2 splice-site variants. The age at commencement of copper-histidine treatment was variable among patients age 7.3 ± 7.5 (0.5-27) months. Despite the treatment, seven patients died before age 5 years, and the remaining patients were severely retarded in neurodevelopment. The poor outcomes of our patients might be related to delayed therapy, but severe ATP7A mutations should be noted as well.

N-terminal domains of the Wilson's and Menkes disease proteins (N-WND and N-MNK) were overexpressed in a soluble form in Escherichia coli as fusions with maltose-binding protein, purified, and their metal-binding properties were characterized. Both N-MNK and N-WND bind copper specifically as indicated by the results of metal-chelate chromatography, direct copper-binding measurements, and chemical modification of Cys residues in the presence of different heavy metals. When E. coli cells are grown in the presence of copper, N-MNK and N-WND bind copper in vivo with stoichiometry of 5-6 nmol of copper/nmol of protein. Copper released from the copper-N-MNK and copper-N-WND complexes reacts with the Cu(I)-selective chelator bicinchoninic acid in the absence of reducing agents. This suggests that in proteins, it is bound in reduced Cu(I) form, in agreement with the spectroscopic properties of the copper-bound domains. Copper bound to the domains in vivo or in vitro specifically protects the N-MNK and N-WND against labeling with the cysteine-directed probe; this indicates that Cys residues in the repetitive motifs GMTCXXCXXXIE are involved in coordination of copper. Direct involvement of the N-terminal domains in the binding of copper suggests their important role in copper-dependent functions of human copper-transporting adenosine triphosphatases (Wilson's and Menkes disease proteins).

To delineate further the clinical spectrum of Menkes disease, an X-linked recessive disorder of copper transport, we studied 4 related males, ranging in age from 4-38 years, with a unique phenotype that combines manifestations of classical and mild Menkes disease and occipital horn syndrome (OHS). The propositus, and 18-year-old man, was evaluated following an intracerebral hemorrhage at age 15 years and was noted to have marked hypotonia, motor delay with mental retardation, bladder diverticula, failure to thrive, and diarrhea from infancy; seizures from age 3 years; and abnormal hair (pili torti) and face, cutis laxa, and multiple joint dislocations. Radiographic abnormalities included occipital exostoses, tortuous cerebral blood vessels with multiple branch occlusions, and hammer-shaped clavicles. Biochemical studies demonstrated reduced copper and ceruloplasmin levels in serum, and abnormal plasma catecholamine ratios. We reported previously the molecular defect in this family, a splice-site mutation that predicts formation of approximately 20% of the normal Menkes gene product [Kaler et al., 1994: Nat Genet 18:195-202]. Here, we detail the clinical course and physical features and radiographic findings in these 4 individuals, and compare their phenotype with classical and mild Menkes and OHS. Unusual Menkes disease variants such as this may escape recognition due to anomalies that appear inconsistent with the diagnosis, particularly prolonged survival and later onset of seizures. Males with mental retardation and connective tissue abnormalities should be evaluated for biochemical evidence of defective copper transport.

eP195: Safety and efficacy of Copper Histidinate (CUTX-101) treatment for Menkes disease caused by severe loss-of-function variants in ATP7A

A Novel Frameshift Mutation in Exon 23 of ATP7A ( MNK) Results in Occipital Horn Syndrome and Not in Menkes Disease

Menkes' kinky hair disease is a poor prognostic congenital disease with X-linked recessive inheritance. This disease is clinically characterized by seizures, friable hair, growth failure, mental retardation and others. Recently it has been known that this disease is also characterized by multiple diverticula of the bladder and other urological abnormalities. A 6-year-old boy was diagnosed as having Menkes' kinky hair disease at another hospital several weeks after birth because of seizures, friable hair and low serum copper level. He voided by Credé's maneuver by the nurse because he could not void for himself. He was referred to our hospital for macrohematuria and micturition pain on October 8, 1989. Right renal staghorn calculus and multiple diverticula of the bladder were found by roentgenographic examination. He has been treated conservatively after discharge because of his poor condition.

The primary mechanism of copper transport to the brain is unknown, although this process is drastically impaired in Menkes disease, an X-linked neurodevelopmental disorder caused by mutations in an evolutionarily conserved copper transporter, ATP7A. Potential central nervous system entry routes for copper include brain capillary endothelial cells that originate from mesodermal angioblasts and form the blood-brain barrier, and the choroid plexuses, which derive from embryonic ectoderm, and form the blood-cerebrospinal fluid barrier. We exploited a rare (and first reported) example of somatic mosaicism for an ATP7A mutation to shed light on questions about copper transport into the developing brain. In a 20-month-old Menkes disease patient evaluated before copper treatment, blood copper, and catecholamine concentrations were normal, whereas levels in cerebrospinal fluid were abnormal and consistent with his neurologically severe phenotype. We documented disparate levels of mosaicism for an ATP7A missense mutation, P1001L, in tissues derived from different embryonic origins; allele quantitation showed P1001L in approximately 27% of DNA samples from blood cells (mesoderm-derived) and 88% from cultured fibroblasts (ectoderm-derived). These findings imply that the P1001L mutation in the patient preceded formation of the three primary embryonic lineages at gastrulation, with the ectoderm layer ultimately harboring a higher percentage of mutation-bearing cells than mesoderm or endoderm. Since choroid plexus epithelia are derived from neuroectoderm, and brain capillary endothelial cells from mesodermal angioblasts, the clinical and biochemical findings in this infant support a critical role for the blood-CSF barrier (choroid plexus epithelia) in copper entry to the developing brain.

Genetic modifier screens provide a useful tool, in diverse organisms from Drosophila to C. elegans and mice, for recovering new genes of interest that may reduce or enhance a phenotype of interest. This study reports a modifier screen, based on N-ethyl-N-nitrosourea (ENU) mutagenesis and outcrossing, designed to increase understanding of the normal function of murine α-synuclein (Snca). Human SNCA was the first gene linked to familial Parkinson’s disease. Since the discovery of the genetic link of SNCA to Parkinson’s nearly three decades ago, numerous studies have investigated the normal function of SNCA protein with divergent roles associated with different cellular compartments. Understanding of the normal function of murine Snca is complicated by the fact that mice with homozygous null mutations live a normal lifespan and have only subtle synaptic deficits. Here, we report that the first genetic modifier (a sensitized mutation) that was identified in our screen was the X-linked gene, ATPase copper transporting alpha (Atp7a). In humans, mutations in Atp7a are linked to to Menkes disease, a disease with pleiotropic phenotypes that include a severe neurological component. Atp7a encodes a trans-Golgi copper transporter that supplies the copper co-factor to enzymes that pass through the ER-Golgi network. Male mice that carry a mutation in Atp7a die within 3 weeks of age regardless of Snca genotype. In contrast, here we show that Snca disruption modifies the phenotype of Atp7a in female mice. Female mice that carry the Atp7a mutation, on an Snca null background, die earlier (prior to 35 days) at a significantly higher rate than those that carry the Atp7a mutation on a wildtype Snca background ATPase copper transporting alpha. Thus, Snca null mutations sensitize female mice to mutations in Atp7a, suggesting that Snca protein may have a protective effect in females, perhaps in neurons, given the co-expression patterns. Although data has suggested diverse functions for human and mouse α-synuclein proteins in multiple cell compartments, this is the first demonstration via use of genetic screening to demonstrate that Snca protein may function in the ER-Golgi system in the mammalian brain in a sex-dependent manner.

During a study of an Amish population of Northern Indiana, 25 individuals with a syndrome of brittle hair, short stature, and intellectual impairment were found in one large kindred. Observations in 20 of these affected individuals have shown that the short stature and intellectual impairment are relatively mild except in the propositus who also has a deletion of a portion of the long arm of chromosome 14. The hair in each affected individual has an abnormal appearance by light and scanning electron microscopy with an irregular grooved surface lacking in scales. Polarization microscopy of the hair revealed an alternating birefringent pattern. Neutron activation analysis of the hair of 11 affected individuals showed the sulfur content to average 2.51% by weight (approximately one half that of controls and nine obligate heterozygotes). This condition can be differentiated from Menkes' kinky-hair syndrome by the microscopic appearance of the hair, the normal copper and ceruloplasmin levels and the mode of inheritance. The syndrome being reported has similarities to and may be identical with a condition previously reported in two siblings by Pollitt et al. in 1968 and that reported in a 4-year-old girl by Brown et al. in 1970. The number of affected individuals and their distribution in this large kindred have provided evidence for the autosomal recessive inheritance of the condition and for its decreased fertility.

Copper acetate solution was administered intravenously to two male infants with Menkes kinky hair syndrome at the age of 4 and 10 months, respectively. The serum copper and ceruloplasmin levels in these cases were markedly low. After copper acetate was initially given by intravenous drip in dose of 180μg/kg every other day, transient adverse reactions attributable to copper such as anemia, hematemesis and bloody stools appeared in one of the patients. These acute copper poisonings disappeared and the general condition was improved after blood transfusion was given. Then copper acetate was administered again slowly (5-6 hours) in dose of 90μg/kg every other day, but no signs of copper poisoning were observed. The serum copper and ceruloplasmin levels increased, then decreased to the normal levels 5-6 weeks after the administration. Further, the administration of copper caused activation of the movement of extremities, but brain damage was not improved.

Copper is vital for numerous cellular functions affecting all tissues and organ systems in the body. The copper pump, ATP7A is critical for whole-body, cellular, and subcellular copper homeostasis, and dysfunction due to genetic defects results in Menkes disease. ATP7A dysfunction leads to copper deficiency in nervous tissue, liver, and blood but accumulation in other tissues. Site-specific cellular deficiencies of copper lead to loss of function of copper-dependent enzymes in all tissues, and the range of Menkes disease pathologies observed can now be explained in full by lack of specific copper enzymes. New pathways involving copper activated lysosomal and steroid sulfatases link patient symptoms usually related to other inborn errors of metabolism to Menkes disease. Additionally, new roles for lysyl oxidase in activation of molecules necessary for the innate immune system, and novel adapter molecules that play roles in ERGIC trafficking of brain receptors and other proteins, are emerging. We here summarize the current knowledge of the roles of copper enzyme function in Menkes disease, with a focus on ATP7A-mediated enzyme metalation in the secretory pathway. By establishing mechanistic relationships between copper-dependent cellular processes and Menkes disease symptoms in patients will not only increase understanding of copper biology but will also allow for the identification of an expanding range of copper-dependent enzymes and pathways. This will raise awareness of rare patient symptoms, and thus aid in early diagnosis of Menkes disease patients.

A pedigree of Menkes' kinky hair disease (MKHD) is reported. One patient of this family who underwent copper treatment was followed for three years with fundus examinations and ERG measurement. The blood copper level remained normal after six months of age, when intravenous treatment was switched from cupric acetate to cupric sulfate. Optic nerve atrophy and decrease in amplitude of the ERG were observed at three years of age. In an experiment using mouse models of MKHD (macular mouse mutant, Moml), we compared the affected mice that received copper treatment with normal mice. However, there was no difference between them in ERG responses, number of ganglion cells, or thickness of retinal layers. These results support the possibility of prolonged survival and maintained vision in the patients of MKHD by earlier normalization of the copper level.

Hypospadias is rarely reported in dogs. In this study we pre-sent 2 novel cases of this disorder of sexual development and, in addition, a case of hereditary sex reversal in a female with an enlarged clitoris. The first case was a male Moscow watchdog with a normal karyotype (78,XY) and the presence of the SRY gene. In this dog, perineal hypospadias, bilateral inguinal cryptorchidism and testes were observed. The second case, representing the Cocker spaniel breed, had a small penis with a hypospadic orifice of the urethra, bilateral cryptorchidism, testis and a rudimentary gonad inside an ovarian bursa, a normal female karyotype (78,XX) and a lack of the SRY gene. This animal was classified as a compound sex reversal (78,XX, SRY-negative) with the hypospadias syndrome. The third case was a Cocker spaniel female with an enlarged clitoris and internally located ovotestes. Cytogenetic and molecular analyses revealed a normal female karyotype (78,XX) and a lack of the SRY gene, while histology of the gonads showed an ovotesticular structure. This case was classified as a typical hereditary sex reversal syndrome (78,XX, SRY-negative). Molecular studies were focused on coding sequences of the SRY gene (case 1) and 2 candidates for monogenic hypospadias, namely MAMLD1 (mastermind-like domain containing 1) and SRD5A2 (steroid-5-alpha-reductase, alpha polypeptide 2). Sequencing of the entire SRY gene, including 5′- and 3′-flanking regions, did not reveal any mutation. The entire coding sequence of MAMLD1 and SRD5A2 was analyzed in all the intersexes, as well as in 4 phenotypically normal control dogs (3 females and 1 male). In MAMLD1 2 SNPs, including 1 missense substitution in exon 1 (c.128A>G, Asp43Ser), were identified, whereas in SRD5A2 7 polymorphisms, including 1 missense SNP (c.358G>A, Ala120Thr), were found. None of the identified polymorphisms cosegregated with the intersexual phenotype, thus, we cannot confirm that hypospadias may be associated with polymorphism in the coding sequence of the studied genes.

The purpose of this study is to identify genotype and phenotype of in Pakistani families with hypodontia and to map the genes locus responsible for this disease. Tooth agenesis known as hypodontia, is a tooth developmental anomaly characterized by congenital absence of one or more teeth. It may occur in primary or secondary dentition and is one of the common craniofacial anomalies. Hypodontia prevalence of is 4.7% for females and 1.3% for males. Third molar agenesis is the most common with an incidence of 20% in general population of Pakistan. The etiology of hypodontia is mainly Genetics whereas environmental factors may also play a role in hypodontia. Blood samples (5ml) were collected from all family members. Genomic DNA was extracted by using inorganic method. All the two coding exons of MSX1 (NM_002448.3) were amplified and sequenced. Sequencing of the MSX1 coding exons and splice sites showed a homozygous missense substitution in exon 1 (c.119C>G p.Ala40Gly) in the two affected individuals of the two families out of fifteen families. We identified a missense mutation (p.Ala40Gly) in MSX1 gene coding exon 1 in two Pakistani families with hypodontia.

Du gène à la maladie : les anomalies des transporteurs du cuivre