Craniometaphyseal Dysplasia Research Articles

Evolution and Spatiotemporal Expression of ankha and ankhb in Zebrafish.

Craniometaphyseal Dysplasia (CMD) is a rare skeletal disorder that can result from mutations in the ANKH gene. This gene encodes progressive anksylosis (ANK), which is responsible for transporting inorganic pyrophosphate (PPi) and ATP from the intracellular to the extracellular environment, where PPi inhibits bone mineralization. When ANK is dysfunctional, as in patients with CMD, the passage of PPi to the extracellular environment is reduced, leading to excess mineralization, particularly in bones of the skull. Zebrafish may serve as a promising model to study the mechanistic basis of CMD. Here, we provide a detailed analysis of the zebrafish Ankh paralogs, Ankha and Ankhb, in terms of their phylogenic relationship with ANK in other vertebrates as well as their spatiotemporal expression patterns during zebrafish development. We found that a closer evolutionary relationship exists between the zebrafish Ankhb protein and its human and other vertebrate counterparts, and stronger promoter activity was predicted for ankhb compared to ankha. Furthermore, we noted distinct temporal expression patterns, with ankha more prominently expressed in early development stages, and both paralogs also being expressed at larval growth stages. Whole-mount in situ hybridization was used to compare the spatial expression patterns of each paralog during bone development, and both showed strong expression in the craniofacial region as well as the notochord and somites. Given the substantial overlap in spatiotemporal expression but only subtle patterning differences, the exact roles of these genes remain speculative. In silico analyses predicted that Ankha and Ankhb have the same function in transporting PPi across the membrane. Nevertheless, this study lays the groundwork for functional analyses of each ankh paralog and highlights the potential of using zebrafish to find possible targeted therapies for CMD.

ENPP1 enzyme replacement therapy improves ectopic calcification but does not rescue skeletal phenotype in a mouse model for craniometaphyseal dysplasia.

Craniometaphyseal dysplasia (CMD) is a rare genetic bone disorder, characterized by progressive thickening of craniofacial bones and flared metaphyses of long bones. Craniofacial hyperostosis leads to the obstruction of neural foramina and neurological symptoms such as facial palsy, blindness, deafness, or severe headache. Mutations in ANKH (mouse ortholog ANK), a transporter of small molecules such as citrate and ATP, are responsible for autosomal dominant CMD. Knock-in (KI) mice carrying an ANKF377del mutation (AnkKI/KI ) replicate many features of human CMD. Pyrophosphate (PPi) levels in plasma are significantly reduced in AnkKI/KI mice. PPi is a potent inhibitor of mineralization. To examine the extent to which restoration of circulating PPi levels may prevent the development of a CMD-like phenotype, we treated AnkKI/KI mice with the recombinant human ENPP1-Fc protein IMA2a. ENPP1 hydrolyzes ATP into AMP and PPi. Male and female Ank+/+ and AnkKI/KI mice (n ≥ 6/group) were subcutaneously injected with IMA2a or vehicle weekly for 12wk, starting at the age of 1wk. Plasma ENPP1 activity significantly increased in AnkKI/KI mice injected with IMA2a (Vehicle/IMA2a: 28.15 ± 1.65/482.7 ± 331.2 mOD/min; p <.01), which resulted in the successful restoration of plasma PPi levels (Ank+/+ /AnkKI/KI vehicle treatment/AnkKI/KI IMA2a: 0.94 ± 0.5/0.43 ± 0.2/1.29 ± 0.8μM; p <.01). We examined the skeletal phenotype by X-Ray imaging and μCT. IMA2a treatment of AnkKI/KI mice did not significantly correct CMD features such as the abnormal shape of femurs, increased bone mass of mandibles, hyperostotic craniofacial bones, or the narrowed foramen magnum. However, μCT imaging showed ectopic calcification near basioccipital bones at the level of the foramen magnum and on joints of AnkKI/KI mice. Interestingly, IMA2a treatment significantly reduced the volume of calcified nodules at both sites. Our data demonstrate that IMA2a is sufficient to restore plasma PPi levels and reduce ectopic calcification but fails to rescue skeletal abnormalities in AnkKI/KI mice under our treatment conditions.

Role of Cx43 on the Bone Cell Generation, Function, and Survival.

The presence of gap junction intercellular communication structures in bone cells has been known since the early 1970s, further confirmed by Doty and Marotti at the structural level in the 1980-1990s. Work by Civitelli, Donahue, and others showed the expression of Cx43 at the mRNA and protein levels in all bone cell types: osteoclasts (bone resorbing cells), osteoblasts (bone forming cells), and osteocytes (mature osteoblasts embedded in the bone matrix that regulate the function of both osteoclasts and osteoblasts). While Cx45, Cx46, and Cx37 were also shown to be expressed in bone cells, most studies have focused on Cx43, the most abundant member of the connexin (Cx) family of proteins expressed in bone. The role of Cx43 has been shown to be related to the formation of gap junction intercellular channels, to unopposed hemichannels, and to channel independent functions of the molecule. Cx43 participates in the response of bone cells to pharmacological, hormonal, and mechanical stimuli, and it is involved in the skeletal phenotype with old age. Human and murine studies have shown that mutations of Cx43 lead to oculodentodigital dysplasia and craniometaphyseal dysplasia, both conditions associated with abnormalities in the skeleton. However, whereas substantial advances have been made on the skeletal role of Cx43, further research is needed to understand the basis for the effects of mutated Cx43 and potential ways to prevent the effects of these mutations on bone.

Transmastoid Facial Nerve Decompression for Craniometaphyseal Dysplasia.

We document the first successful transmastoid surgical treatment of facial nerve palsy for a patient with craniometaphyseal dysplasia (CMD), a rare genetic disease. A 9-month-old girl with bilateral facial nerve palsies and conductive hearing loss. Genetic testing made a diagnosis of CMD, and imaging showed narrowing of the facial nerve canals and ossicular fixation. Right transmastoid facial nerve decompression and ossicular chain reconstruction. Facial nerve function (House-Brackmann grade). Facial nerve function initially worsened, then improved within 12 months from House-Brackmann grade IV-V to grade III. Surgical cranial nerve decompression of and ossicular chain reconstruction may be effective treatments for patients with CMD.

Three-dimensional radiographic features of craniometaphyseal dysplasia—a comparative CBCT study

PurposeCraniometaphyseal dysplasia (CMD) is a rare skeletal disorder that has progressive thickening and increased density of the craniofacial bones along with abnormal metaphyses of the long bones. Other features include a wide nasal bridge, paranasal bossing, hypertelorism, and an increase in the zygomatic width. We present a series of cases that showcase the three-dimensional radiographic features of this rare condition and compare it with an age and gender-matched controlled group using cone beam computed tomography (CBCT).ObjectiveTo evaluate the three-dimensional radiographic features of craniometaphyseal dysplasia (CMD).Materials and methodsRetrospective analysis of CBCT scans of 7 patients who were diagnosed with the rare condition craniometaphyseal dysplasia was evaluated. Radiographic features of the craniofacial bones, the paranasal sinuses prominently maxillary, and frontal and sphenoid sinuses were evaluated. Skull bones were also evaluated, and the size and shape of the sella turcica and external auditory meatus were measured. Retained primary teeth and impactions were evaluated using a panoramic reformatted image. The type of occlusion and buccolingual dimensions of jaw bones were also assessed. Age and gender-matched control samples were used to measure the same features for comparing CMD patients to healthy controls. The quality of normal and syndromic patients’ cortical and trabecular bone was determined by measuring pixel intensity values (PIV) generated by CBCT scans.ResultsCone beam CT images of patients with CMD were analyzed to evaluate cranial bones, their density, and any abnormalities associated with the sinuses and foramina. Patients with CMD had bones increased in size. A significant increase in the amount of bone formed was found in the inner table of the frontal and occipital bones. All seven patients with CMD had smaller foramina due to the deposition of sclerosed bone in the foramina of the skull base. The paranasal sinuses, prominently maxillary and frontal and sphenoid sinuses, were smaller than the age and gender-matched controls. The buccolingual dimensions of jawbones were increased. The maxillary and mandibular arch relationship ranged from class II to class III. The mean nasal bridge measurement for the CMD patients was 26.77 mm, while in the controls, the mean nasal bridge measurement was 19.48 mm. The mean measurements of the right and left orbits of CMD patients were 30.6 mm and 31.07 mm respectively, and the mean measurements of the right and left orbits of controls were 32.45 mm and 32.04 mm. Pixel intensity values (PIVs) representing density ranged between 100 and 1000 PIVs for cortical bone and between − 60 and 258 for trabecular bone suggesting a densely sclerotic texture, while in the control group patients, the PIVs for cortical bone were > 1000 and 150–300 for trabecular bone.ConclusionCMD patients had significantly larger bone widths, a lower density of the bone, and smaller sinuses compared to the control group.

Posterior Vault Distraction for Multi-Suture Craniosynostosis in a Patient with Craniometaphyseal Dysplasia: A Case Report

Study Design Case report Objective Syndromic multi-suture craniosynostosis can result in complex dysmorphology and increased intracranial pressure. We present a case report of a child with craniometaphyseal dysplasia and syndromic multi-suture craniosynostosis who presented with increased intracranial pressure, ventriculomegaly and Chiari deformity Type 1. Methods The child underwent a posterior vault distraction to increase the intracranial volume. Results The posterior cranial expansion was successful in correcting the craniocerebral disproportion caused by multi-suture synostosis, and resolved the high intracranial pressure and papilloedema. There were no post-operative complications. Conclusions Posterior cranial vault distraction was an effective method of addressing increased intracranial pressure by correcting craniocerebral disproportion by increasing intracranial volume and also addressing the Chiari Type I deformity that resulted from syndromic multi-suture craniosynostosis in a child with craniometaphyseal dysplasia.

Research Advances of Human Homologue of Mouse Progressive Ankylosis Protein and Bone and Joint Diseases

The human homologue of mouse progressive ankylosis protein(ANKH)is an inorganic pyrophosphate transport regulator,which regulates tissue mineralization by controlling the level of inorganic pyrophosphate.It plays an important role in the pathogenesis and development of bone and joint diseases,such as ankylosing spondylitis,craniometaphyseal dysplasia,and articular cartilage calcification.This review summarizes the progress of research on ANKH and the above-mentioned diseases.

Simultaneous LeFort III and LeFort I Osteotomies in Craniometaphyseal Dysplasia

Craniometaphyseal dysplasia (CMD) is a rare genetic disease affecting bone metabolism with sclerosis of craniofacial bones. Orthognathic surgery has rarely been described in this patient population due to the bony thickness, making osteotomies challenging. We present a 19-year-old male with CMD with malocclusion, severe midface hypoplasia, and obstructive sleep apnea. With the aid virtual planning, we safely performed a combined LeFort III/I midface advancement to correct a negative overjet to improve occlusal balance, decrease scleral show, and diminish daytime sleepiness.

キアリ奇形Ⅰ型を伴った頭蓋骨幹端異形成症に対し, 大後頭孔減圧術 (foramen magnum decompression : FMD) が奏効した1例

キアリ奇形Ⅰ型を伴った頭蓋骨幹端異形成症に対し, 大後頭孔減圧術 (foramen magnum decompression : FMD) が奏効した1例

Connexin 43 in osteogenesis

Skeleton formation and its proper functioning is possible thanks to specialized bone tissue cells: bone forming osteoblasts, bone resorbing osteoclasts and osteocytes located in bone cavities. Gap junctions are transmembrane channels connecting neighboring cell. Thanks to gap junctions it is possible for signals to be directly transmitted by cells. Gap junction type channels, and more specifically the connexin proteins that build them, have a key impacton the bone turnover process, and thus on both bone building and remodeling. A particularly important connexin in bone tissue is connexin43 (Cx43), which is necessary in the proper course of the bone formation process and in maintaining bone homeostasis. The importance of the presence of Cx43 in bones is showed by skeletal defects in diseases such as ODD syndrome and craniometaphyseal dysplasia caused by mutations in GJA1, the gene encoding Cx43. The role of Cx43 in the differentiation of stem cells into bone cells, anti-apoptotic action of bisphosphonates and bone responses to hormonal and mechanical stimuli have also been demonstrated. In addition to connexin43, the presence of other connexins such as connexin45, 46 and 37 was also noted in bone tissue.

Restriction of Dietary Phosphate Ameliorates Skeletal Abnormalities in a Mouse Model for Craniometaphyseal Dysplasia.

Craniometaphyseal dysplasia (CMD), a rare genetic bone disorder, is characterized by lifelong progressive thickening of craniofacial bones and metaphyseal flaring of long bones. The autosomal dominant form of CMD is caused by mutations in the progressive ankylosis gene ANKH (mouse ortholog Ank), encoding a pyrophosphate (PPi) transporter. We previously reported reduced formation and function of osteoblasts and osteoclasts in a knockin (KI) mouse model for CMD (AnkKI/KI) and in CMD patients. We also showed rapid protein degradation of mutant ANK/ANKH. Mutant ANK protein displays reduced PPi transport, which may alter the inorganic phosphate (Pi) and PPi ratio, an important regulatory mechanism for bone mineralization. Here we investigate whether reducing dietary Pi intake can ameliorate the CMD-like skeletal phenotype by comparing male and female Ank+/+ and AnkKI/KI mice exposed to a low (0.3%) and normal (0.7%) Pi diet for 13 weeks from birth. Serum Pi and calcium (Ca) levels were not significantly changed by diet, whereas PTH and 25-hydroxy vitamin D (25-OHD) were decreased by low Pi diet but only in male Ank+/+ mice. Importantly, the 0.3% Pi diet significantly ameliorated mandibular hyperostosis in both sexes of AnkKI/KI mice. A tendency of decreased femoral trabeculation was observed in male and female Ank+/+ mice as well as in male AnkKI/KI mice fed with the 0.3% Pi diet. In contrast, in female AnkKI/KI mice the 0.3% Pi diet resulted in increased metaphyseal trabeculation. This was also the only group that showed increased bone formation rate. Low Pi diet led to increased osteoclast numbers and increased bone resorption in all mice. We conclude that lowering but not depleting dietary Pi delays the development of craniofacial hyperostosis in CMD mice without severely compromising serum levels of Pi, Ca, PTH, and 25-OHD. These findings may have implications for better clinical care of patients with CMD. © 2020 American Society for Bone and Mineral Research.

Differences in intracellular localisation of ANKH mutants that relate to mechanisms of calcium pyrophosphate deposition disease and craniometaphyseal dysplasia

ANKH mutations are associated with calcium pyrophosphate deposition disease and craniometaphyseal dysplasia. This study investigated the effects of these ANKH mutants on cellular localisation and associated biochemistry. We generated four ANKH overexpression-plasmids containing either calcium pyrophosphate deposition disease or craniometaphyseal dysplasia linked mutations: P5L, E490del and S375del, G389R. They were transfected into CH-8 articular chondrocytes and HEK293 cells. The ANKH mutants dynamic differential localisations were imaged and we investigated the interactions with the autophagy marker LC3. Extracellular inorganic pyrophosphate, mineralization, ENPP1 activity expression of ENPP1, TNAP and PIT-1 were measured. P5L delayed cell membrane localisation but once recruited into the membrane it increased extracellular inorganic pyrophosphate, mineralization, and ENPP1 activity. E490del remained mostly cytoplasmic, forming punctate co-localisations with LC3, increased mineralization, ENPP1 and ENPP1 activity with an initial but unsustained increase in TNAP and PIT-1. S375del trended to decrease extracellular inorganic pyrophosphate, increase mineralization. G389R delayed cell membrane localisation, trended to decrease extracellular inorganic pyrophosphate, increased mineralization and co-localised with LC3. Our results demonstrate a link between pathological localisation of ANKH mutants with different degrees in mineralization. Furthermore, mutant ANKH functions are related to synthesis of defective proteins, inorganic pyrophosphate transport, ENPP1 activity and expression of ENPP1, TNAP and PIT-1.

Optic nerve decompression in Craniofacial fibrous dysplasia involving optic canal: An experience at AIIMS, New Delhi

Background: Gradual progression of craniofacial fibrous dysplasia frequently involves sphenoid and ethmoid bone results encasement of optic canal which leads to visual impairment to complete blindness&#x0D; Methods: Retrospective study was carried out at All India Institute of Medical Sciences on hospital records of 16 cases of craniofacial fibrous dysplasia operated for optic canal involvement with or without visual impairment with an objective to discuss about the indications, suitable timing and outcome of optic nerve decompression in cases of optic canal involvement.&#x0D; Results: Out of 16 cases, 56.25% were female with mean age 13.06 years. 15 patients had Idiopathic Fibrous dysplasia and 01 had Cranio-metaphyseal dysplasia. 62.5% were polyostotic and 37.5% were monostotic with 62.5% of optic neuropathy. Bilateral lesion occurred in 03 patients. Optic nerve decompression was done for curative treatment in 62.5% and for prophylactic in 37.5% cases. Post-operative visual improvement occurred in 90% patients and in no patient vision was deteriorated.&#x0D; Conclusion: Prophylactic decompression can be carried out in expert hand for involvement of optic canal in craniofacial fibrous dysplasia for prevention of future visual impairment&#x0D; Bangladesh J of Otorhinolaryngology; October 2018; 24(2): 94-104

Rapid degradation of progressive ankylosis protein (ANKH) in craniometaphyseal dysplasia

Mutations in the progressive ankylosis protein (NP_473368, human ANKH) cause craniometaphyseal dysplasia (CMD), characterized by progressive thickening of craniofacial bones and widened metaphyses in long bones. The pathogenesis of CMD remains largely unknown, and treatment for CMD is limited to surgical intervention. We have reported that knock-in mice (AnkKI/KI) carrying a F377del mutation in ANK (NM_020332, mouse ANK) replicate many features of CMD. Interestingly, ablation of the Ank gene in AnkKO/KO mice also leads to several CMD-like phenotypes. Mutations causing CMD led to decreased steady-state levels of ANK/ANKH protein due to rapid degradation. While wild type (wt) ANK was mostly associated with plasma membranes, endoplasmic reticulum (ER), Golgi apparatus and lysosomes, CMD-linked mutant ANK was aberrantly localized in cytoplasm. Inhibitors of proteasomal degradation significantly restored levels of overexpressed mutant ANK, whereas endogenous CMD-mutant ANK/ANKH levels were more strongly increased by inhibitors of lysosomal degradation. However, these inhibitors do not correct the mislocalization of mutant ANK. Co-expressing wt and CMD-mutant ANK in cells showed that CMD-mutant ANK does not negatively affect wt ANK expression and localization, and vice versa. In conclusion, our finding that CMD mutant ANK/ANKH protein is short-lived and mislocalized in cells may be part of the CMD pathogenesis.

Craniometaphyseal Dysplasia Mutations in ANKH Negatively Affect Human Induced Pluripotent Stem Cell Differentiation into Osteoclasts

SummaryWe identified osteoclast defects in craniometaphyseal dysplasia (CMD) using an easy-to-use protocol for differentiating osteoclasts from human induced pluripotent stem cells (hiPSCs). CMD is a rare genetic bone disorder, characterized by life-long progressive thickening of craniofacial bones and abnormal shape of long bones. hiPSCs from CMD patients with an in-frame deletion of Phe377 or Ser375 in ANKH are more refractory to in vitro osteoclast differentiation than control hiPSCs. To exclude differentiation effects due to genetic variability, we generated isogenic hiPSCs, which have identical genetic background except for the ANKH mutation. Isogenic hiPSCs with ANKH mutations formed fewer osteoclasts, resorbed less bone, expressed lower levels of osteoclast marker genes, and showed decreased protein levels of ANKH and vacuolar proton pump v-ATP6v0d2. This proof-of-concept study demonstrates that efficient and reproducible differentiation of isogenic hiPSCs into osteoclasts is possible and a promising tool for investigating mechanisms of CMD or other osteoclast-related disorders.

Craniometaphyseal Dysplasia: A review and novel oral manifestation

Craniometaphyseal Dysplasia (CMD) is a sclerosing osseous dysplasia characterised by hyperostosis of craniofacial and long bones, resulting in distortion and cranial nerve palsies.We present a case report on the management of a 63year old female with Craniometaphyseal Dysplasia. This report describes an additional clinical manifestation of hypercementosis, which although well recognised in other sclerosing osseous dysplasias, is not reported in the literature for Craniometaphyseal Dysplasia. We discuss established in vivo studies in mice which link the genetic mutations found in Craniometaphyseal Dysplasia to hypercementosis, and how this report describes the same manifestation in humans.This novel finding can aid the clinician in the management of patients with Craniometaphyseal Dysplasia, and complications that can arise in dentoalveolar surgery.

An atypical case of craniometaphyseal dysplasia. Case report and surgical treatment.

Craniometaphyseal dysplasia is a rare hereditary bone disease presenting metaphyseal widening of the tubular bones, sclerosis of craniofacial bones and bony overgrowth of the facial and skull bones. Craniometaphyseal dysplasia occurs in an autosomal dominant (AD) and an autosomal recessive (AR) form. We present a 32-year-old patient arrived at our unit in May 2009. His main discomfort was a major limitation of the mouth opening, in the context of a craniofacial deformity. Relying on patient's medical history and the performed diagnostic tests, the diagnosis of craniometaphyseal dysplasia was made. After careful evaluation of the clinical case, in accordance with the requirements of the patient, we opted for a surgical treatment aimed at correction of functional limitation of temporomandibular joint and aesthetic improvement of the facial bones. The stability of the clinical results led us to suggest and to undertake the surgical path, also due to the lack of safe and consolidated non-surgical treatments for the specific case.

Dental Manifestations and Surgical Management of Craniometaphyseal Dysplasia: A Case Report

Dental Manifestations and Surgical Management of Craniometaphyseal Dysplasia: A Case Report

Dietary phosphate supplement does not rescue skeletal phenotype in a mouse model for craniometaphyseal dysplasia.

BackgroundMutations in the human progressive ankylosis gene (ANKH; Mus musculus ortholog Ank) have been identified as cause for craniometaphyseal dysplasia (CMD), characterized by progressive thickening of craniofacial bones and flared metaphyses of long bones. We previously reported a knock-in (KI) mouse model (Ank KI/KI) for CMD and showed transiently lower serum phosphate (Pi) as well as significantly higher mRNA levels of fibroblast growth factor 23 (Fgf23) in Ank KI/KI mice. FGF23 is secreted by bone and acts in kidney to promote Pi wasting which leads to lower serum Pi levels. Here, we examined whether increasing the Pi level can partially rescue the CMD-like skeletal phenotype by feeding Ank +/+ and Ank KI/KI mice with high Pi (1.7 %) diet from birth for 6 weeks. We studied the Pi metabolism in Ank KI/KI mice and CMD patients by examining the Pi regulators FGF23 and parathyroid hormone (PTH).ResultsHigh Pi diet did not correct CMD-like features, including massive jawbone, increased endosteal and periosteal perimeters and extensive trabeculation of femurs in Ank KI/KI mice shown by computed microtomography (μCT). This unexpected negative result is, however, consistent with normal serum/plasma levels of the intact/active form of FGF23 and PTH in Ank KI/KI mice and in CMD patients. In addition, FGF23 protein expression was unexpectedly normal in Ank KI/KI femoral cortical bone as shown by immunohistochemistry despite increased mRNA levels for Fgf23. Renal expression of genes involved in the FGF23 bone-kidney axis, including mFgfr1, mKlotho, mNpt2a, mCyp24a1 and m1αOHase, were comparable between Ank +/+ and Ank KI/KI mice as shown by quantitative real-time PCR. Different from normal FGF23 and PTH, serum 25-hydroxyvitamin D was significantly lower in Ank KI/KI mice and vitamin D insufficiency was found in four out of seven CMD patients.ConclusionsOur data suggests that FGF23 signaling and Pi metabolism are not significantly affected in CMD and transiently low Pi level is not a major contributor to CMD.

The progressive ankylosis protein ANK facilitates clathrin- and adaptor-mediated membrane traffic at the trans-Golgi network-to-endosome interface.

Dominant or recessive mutations in the progressive ankylosis gene ANKH have been linked to familial chondrocalcinosis (CCAL2), craniometaphyseal dysplasia (CMD), mental retardation, deafness and ankylosis syndrome (MRDA). The function of the encoded membrane protein ANK in cellular compartments other than the plasma membrane is unknown. Here, we show that ANK localizes to the trans-Golgi network (TGN), clathrin-coated vesicles and the plasma membrane. ANK functionally interacts with clathrin and clathrin associated adaptor protein (AP) complexes as loss of either protein causes ANK dispersion from the TGN to cytoplasmic endosome-like puncta. Consistent with its subcellular localization, loss of ANK results in reduced formation of tubular membrane carriers from the TGN, perinuclear accumulation of early endosomes and impaired transferrin endocytosis. Our data indicate that clathrin/AP-mediated cycling of ANK between the TGN, endosomes, and the cell surface regulates membrane traffic at the TGN/endosomal interface. These findings suggest that dysfunction of Golgi-endosomal membrane traffic may contribute to ANKH-associated pathologies.