A rare superficial pemphigus disease characterized by multiple, pruritic, scaly, crusted cutaneous erosions, with flaky circumscribed patches, localized mostly on the face, scalp, trunk and extremities, often presenting an erythematous base. Mucosal involvement is rarely observed.

Bassuk et al. (2003) reported an infant with Alexander disease who presented with poor feeding on the first day of life, followed by emesis and weight loss. ... Stumpf et al. (2003) reported a family with an autosomal dominant adult form of Alexander disease. ... Although this sibship suggested possible autosomal recessive inheritance, all the molecular genetic evidence favors autosomal dominant inheritance, i.e., de novo heterozygous mutations as the cause. ... The data confirmed that the effects of the specific GFAP mutation are dominant; in the heterozygote mutant, the gene product was dominant over wildtype GFAP in coassembly experiments (Der Perng et al., 2006). ... It remained to be determined whether the heritable dominant forms of Alexander disease described in 2 families, both of which had late onsets after age 25 years (Howard et al., 1993; Schwankhaus et al., 1995), also had GFAP mutations as the cause.

An astrogliopathy and a form of Alexander disease (AxD) characterized by ataxia, bulbar symptoms, spastic paraparesis, palatal myoclonus, and autonomic symptoms. Epidemiology Prevalence is unknown. It accounts for approximately 40% of AxD cases. Clinical description AxD type II can present throughout life, most commonly in late adolescence or adulthood (over the age of 12) and more rarely in childhood, with the age of onset ranging from 4-62 in published cases. It presents most commonly with bulbar symptoms (dysarthria, dysphonia, dysphagia), pyramidal signs and gait difficulties due to ataxia and/or spastic paraparesis. Unlike AxD type I (see this term), seizures are rarely seen and cognitive impairment is sometimes absent.

Those with a neonatal onset (within the first 30 days) usually have a more severe disease course presenting with symptoms of generalized, frequent, and often intractable seizures, aqueductal stenosis (leading to hydrocephalus with raised intracranial pressure) and severe motor and intellectual disability. ... The disease course is severe with death usually, but not always, occurring in the first two decades after diagnosis. In the neonatal form the disease progresses even faster with severe disability or death occurring within the first years of life.

Several familial cases have also been reported with autosomal dominant transmission. This gene encodes GFAP, the major intermediate filament protein found in astrocytes.

While this condition is inherited in an autosomal dominant fashion, most cases result from new mutations in the gene.

Sequence analysis of GFAP is performed first to detect small intragenic deletions/insertions and missense, nonsense, and splice site variants. Note: Depending on the sequencing method used, single-exon, multiexon, or whole-gene deletions/duplications may not be detected. If no variant is detected by the sequencing method used, the next step is to perform gene-targeted deletion/duplication analysis to detect exon and whole-gene deletions or duplications. ... Variants may include small intragenic deletions/insertions and missense, nonsense, and splice site variants; typically, exon or whole-gene deletions/duplications are not detected. ... Disease progression is also variable, with some individuals losing gross and fine motor as well as language skills in the first decade of life, while others follow a very slow disease course that spans decades.

Rarely, a neonatal form of Alexander disease occurs within the first month of life and is associated with severe intellectual disability and developmental delay, a buildup of fluid in the brain (hydrocephalus), and seizures. ... About 500 cases have been reported since the disorder was first described in 1949. Causes Mutations in the GFAP gene cause Alexander disease. ... Learn more about the gene associated with Alexander disease GFAP Inheritance Pattern This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder.

EDAR mutations can have an autosomal dominant or autosomal recessive pattern of inheritance, and EDARADD mutations have an autosomal recessive pattern of inheritance. Autosomal dominant inheritance means one copy of the altered gene in each cell is sufficient to cause the disorder. ... Most often, the parents of an individual with an autosomal recessive disorder are carriers of one copy of the altered gene but do not show signs and symptoms of the disorder. [ citation needed ] Terminology [ edit ] The eponym Christ-Siemens-Touraine syndrome was named after its discoverers: Josef Christ (1871–1948), a German dentist and physician from Wiesbaden , who was the first physician to identify the condition, Hermann Werner Siemens (1891–1969), a pioneering German dermatologist from Charlottenburg , who clearly identified its pathological characteristics in the early 1930s, and Albert Touraine (1883–1961), a French dermatologist who likewise noted and identified additional characteristics of the disease in the late 1930s. [ citation needed ] Notable individuals [ edit ] Michael Berryman , Saturn Award -nominated character actor See also [ edit ] Hermann Werner Siemens List of cutaneous conditions Albert Touraine List of radiographic findings associated with cutaneous conditions List of dental abnormalities associated with cutaneous conditions References [ edit ] ^ James, William; Berger, Timothy; Elston, Dirk (2005). ... External links [ edit ] GeneReview/NIH/UW entry on Hypohidrotic Ectodermal Dysplasia Hypohidrotic ectodermal dysplasia at NLM Genetics Home Reference Classification D ICD - 10 : Q82.4 ICD - 9-CM : 757.31 OMIM : 305100 224900 , 129490 MeSH : D053358 DiseasesDB : 29810 External resources GeneReviews : Hypohidrotic Ectodermal Dysplasia v t e Congenital malformations and deformations of integument / skin disease Genodermatosis Congenital ichthyosis / erythrokeratodermia AD Ichthyosis vulgaris AR Congenital ichthyosiform erythroderma : Epidermolytic hyperkeratosis Lamellar ichthyosis Harlequin-type ichthyosis Netherton syndrome Zunich–Kaye syndrome Sjögren–Larsson syndrome XR X-linked ichthyosis Ungrouped Ichthyosis bullosa of Siemens Ichthyosis follicularis Ichthyosis prematurity syndrome Ichthyosis–sclerosing cholangitis syndrome Nonbullous congenital ichthyosiform erythroderma Ichthyosis linearis circumflexa Ichthyosis hystrix EB and related EBS EBS-K EBS-WC EBS-DM EBS-OG EBS-MD EBS-MP JEB JEB-H Mitis Generalized atrophic JEB-PA DEB DDEB RDEB related: Costello syndrome Kindler syndrome Laryngoonychocutaneous syndrome Skin fragility syndrome Ectodermal dysplasia Naegeli syndrome / Dermatopathia pigmentosa reticularis Hay–Wells syndrome Hypohidrotic ectodermal dysplasia Focal dermal hypoplasia Ellis–van Creveld syndrome Rapp–Hodgkin syndrome / Hay–Wells syndrome Elastic / Connective Ehlers–Danlos syndromes Cutis laxa ( Gerodermia osteodysplastica ) Popliteal pterygium syndrome Pseudoxanthoma elasticum Van der Woude syndrome Hyperkeratosis / keratinopathy PPK diffuse : Diffuse epidermolytic palmoplantar keratoderma Diffuse nonepidermolytic palmoplantar keratoderma Palmoplantar keratoderma of Sybert Meleda disease syndromic connexin Bart–Pumphrey syndrome Clouston's hidrotic ectodermal dysplasia Vohwinkel syndrome Corneodermatoosseous syndrome plakoglobin Naxos syndrome Scleroatrophic syndrome of Huriez Olmsted syndrome Cathepsin C Papillon–Lefèvre syndrome Haim–Munk syndrome Camisa disease focal : Focal palmoplantar keratoderma with oral mucosal hyperkeratosis Focal palmoplantar and gingival keratosis Howel–Evans syndrome Pachyonychia congenita Pachyonychia congenita type I Pachyonychia congenita type II Striate palmoplantar keratoderma Tyrosinemia type II punctate : Acrokeratoelastoidosis of Costa Focal acral hyperkeratosis Keratosis punctata palmaris et plantaris Keratosis punctata of the palmar creases Schöpf–Schulz–Passarge syndrome Porokeratosis plantaris discreta Spiny keratoderma ungrouped: Palmoplantar keratoderma and spastic paraplegia desmoplakin Carvajal syndrome connexin Erythrokeratodermia variabilis HID / KID Other Meleda disease Keratosis pilaris ATP2A2 Darier's disease Dyskeratosis congenita Lelis syndrome Dyskeratosis congenita Keratolytic winter erythema Keratosis follicularis spinulosa decalvans Keratosis linearis with ichthyosis congenita and sclerosing keratoderma syndrome Keratosis pilaris atrophicans faciei Keratosis pilaris Other cadherin EEM syndrome immune system Hereditary lymphedema Mastocytosis / Urticaria pigmentosa Hailey–Hailey see also Template:Congenital malformations and deformations of skin appendages , Template:Phakomatoses , Template:Pigmentation disorders , Template:DNA replication and repair-deficiency disorder Developmental anomalies Midline Dermoid cyst Encephalocele Nasal glioma PHACE association Sinus pericranii Nevus Capillary hemangioma Port-wine stain Nevus flammeus nuchae Other/ungrouped Aplasia cutis congenita Amniotic band syndrome Branchial cyst Cavernous venous malformation Accessory nail of the fifth toe Bronchogenic cyst Congenital cartilaginous rest of the neck Congenital hypertrophy of the lateral fold of the hallux Congenital lip pit Congenital malformations of the dermatoglyphs Congenital preauricular fistula Congenital smooth muscle hamartoma Cystic lymphatic malformation Median raphe cyst Melanotic neuroectodermal tumor of infancy Mongolian spot Nasolacrimal duct cyst Omphalomesenteric duct cyst Poland anomaly Rapidly involuting congenital hemangioma Rosenthal–Kloepfer syndrome Skin dimple Superficial lymphatic malformation Thyroglossal duct cyst Verrucous vascular malformation Birthmark v t e X-linked disorders X-linked recessive Immune Chronic granulomatous disease (CYBB) Wiskott–Aldrich syndrome X-linked severe combined immunodeficiency X-linked agammaglobulinemia Hyper-IgM syndrome type 1 IPEX X-linked lymphoproliferative disease Properdin deficiency Hematologic Haemophilia A Haemophilia B X-linked sideroblastic anemia Endocrine Androgen insensitivity syndrome / Spinal and bulbar muscular atrophy KAL1 Kallmann syndrome X-linked adrenal hypoplasia congenita Metabolic Amino acid : Ornithine transcarbamylase deficiency Oculocerebrorenal syndrome Dyslipidemia : Adrenoleukodystrophy Carbohydrate metabolism : Glucose-6-phosphate dehydrogenase deficiency Pyruvate dehydrogenase deficiency Danon disease/glycogen storage disease Type IIb Lipid storage disorder : Fabry's disease Mucopolysaccharidosis : Hunter syndrome Purine–pyrimidine metabolism : Lesch–Nyhan syndrome Mineral : Menkes disease / Occipital horn syndrome Nervous system X-linked intellectual disability : Coffin–Lowry syndrome MASA syndrome Alpha-thalassemia mental retardation syndrome Siderius X-linked mental retardation syndrome Eye disorders: Color blindness (red and green, but not blue) Ocular albinism ( 1 ) Norrie disease Choroideremia Other: Charcot–Marie–Tooth disease (CMTX2-3) Pelizaeus–Merzbacher disease SMAX2 Skin and related tissue Dyskeratosis congenita Hypohidrotic ectodermal dysplasia (EDA) X-linked ichthyosis X-linked endothelial corneal dystrophy Neuromuscular Becker's muscular dystrophy / Duchenne Centronuclear myopathy (MTM1) Conradi–Hünermann syndrome Emery–Dreifuss muscular dystrophy 1 Urologic Alport syndrome Dent's disease X-linked nephrogenic diabetes insipidus Bone / tooth AMELX Amelogenesis imperfecta No primary system Barth syndrome McLeod syndrome Smith–Fineman–Myers syndrome Simpson–Golabi–Behmel syndrome Mohr–Tranebjærg syndrome Nasodigitoacoustic syndrome X-linked dominant X-linked hypophosphatemia Focal dermal hypoplasia Fragile X syndrome Aicardi syndrome Incontinentia pigmenti Rett syndrome CHILD syndrome Lujan–Fryns syndrome Orofaciodigital syndrome 1 Craniofrontonasal dysplasia v t e Deficiencies of intracellular signaling peptides and proteins GTP-binding protein regulators GTPase-activating protein Neurofibromatosis type I Watson syndrome Tuberous sclerosis Guanine nucleotide exchange factor Marinesco–Sjögren syndrome Aarskog–Scott syndrome Juvenile primary lateral sclerosis X-Linked mental retardation 1 G protein Heterotrimeic cAMP / GNAS1 : Pseudopseudohypoparathyroidism Progressive osseous heteroplasia Pseudohypoparathyroidism Albright's hereditary osteodystrophy McCune–Albright syndrome CGL 2 Monomeric RAS: HRAS Costello syndrome KRAS Noonan syndrome 3 KRAS Cardiofaciocutaneous syndrome RAB: RAB7 Charcot–Marie–Tooth disease RAB23 Carpenter syndrome RAB27 Griscelli syndrome type 2 RHO: RAC2 Neutrophil immunodeficiency syndrome ARF : SAR1B Chylomicron retention disease ARL13B Joubert syndrome 8 ARL6 Bardet–Biedl syndrome 3 MAP kinase Cardiofaciocutaneous syndrome Other kinase / phosphatase Tyrosine kinase BTK X-linked agammaglobulinemia ZAP70 ZAP70 deficiency Serine/threonine kinase RPS6KA3 Coffin-Lowry syndrome CHEK2 Li-Fraumeni syndrome 2 IKBKG Incontinentia pigmenti STK11 Peutz–Jeghers syndrome DMPK Myotonic dystrophy 1 ATR Seckel syndrome 1 GRK1 Oguchi disease 2 WNK4 / WNK1 Pseudohypoaldosteronism 2 Tyrosine phosphatase PTEN Bannayan–Riley–Ruvalcaba syndrome Lhermitte–Duclos disease Cowden syndrome Proteus-like syndrome MTM1 X-linked myotubular myopathy PTPN11 Noonan syndrome 1 LEOPARD syndrome Metachondromatosis Signal transducing adaptor proteins EDARADD EDARADD Hypohidrotic ectodermal dysplasia SH3BP2 Cherubism LDB3 Zaspopathy Other NF2 Neurofibromatosis type II NOTCH3 CADASIL PRKAR1A Carney complex PRKAG2 Wolff–Parkinson–White syndrome PRKCSH PRKCSH Polycystic liver disease XIAP XIAP2 See also intracellular signaling peptides and proteins v t e Cell surface receptor deficiencies G protein-coupled receptor (including hormone ) Class A TSHR ( Congenital hypothyroidism 1 ) LHCGR ( Luteinizing hormone insensitivity , Leydig cell hypoplasia , Male-limited precocious puberty ) FSHR ( Follicle-stimulating hormone insensitivity , XX gonadal dysgenesis ) GnRHR ( Gonadotropin-releasing hormone insensitivity ) EDNRB ( ABCD syndrome , Waardenburg syndrome 4a , Hirschsprung's disease 2 ) AVPR2 ( Nephrogenic diabetes insipidus 1 ) PTGER2 ( Aspirin-induced asthma ) Class B PTH1R ( Jansen's metaphyseal chondrodysplasia ) Class C CASR ( Familial hypocalciuric hypercalcemia ) Class F FZD4 ( Familial exudative vitreoretinopathy 1 ) Enzyme-linked receptor (including growth factor ) RTK ROR2 ( Robinow syndrome ) FGFR1 ( Pfeiffer syndrome , KAL2 Kallmann syndrome ) FGFR2 ( Apert syndrome , Antley–Bixler syndrome , Pfeiffer syndrome , Crouzon syndrome , Jackson–Weiss syndrome ) FGFR3 ( Achondroplasia , Hypochondroplasia , Thanatophoric dysplasia , Muenke syndrome ) INSR ( Donohue syndrome Rabson–Mendenhall syndrome ) NTRK1 ( Congenital insensitivity to pain with anhidrosis ) KIT ( KIT Piebaldism , Gastrointestinal stromal tumor ) STPK AMHR2 ( Persistent Müllerian duct syndrome II ) TGF beta receptors : Endoglin / Alk-1 / SMAD4 ( Hereditary hemorrhagic telangiectasia ) TGFBR1 / TGFBR2 ( Loeys–Dietz syndrome ) GC GUCY2D ( Leber's congenital amaurosis 1 ) JAK-STAT Type I cytokine receptor : GH ( Laron syndrome ) CSF2RA ( Surfactant metabolism dysfunction 4 ) MPL ( Congenital amegakaryocytic thrombocytopenia ) TNF receptor TNFRSF1A ( TNF receptor associated periodic syndrome ) TNFRSF13B ( Selective immunoglobulin A deficiency 2 ) TNFRSF5 ( Hyper-IgM syndrome type 3 ) TNFRSF13C ( CVID4 ) TNFRSF13B ( CVID2 ) TNFRSF6 ( Autoimmune lymphoproliferative syndrome 1A ) Lipid receptor LRP : LRP2 ( Donnai–Barrow syndrome ) LRP4 ( Cenani–Lenz syndactylism ) LRP5 ( Worth syndrome , Familial exudative vitreoretinopathy 4 , Osteopetrosis 1 ) LDLR ( LDLR Familial hypercholesterolemia ) Other/ungrouped Immunoglobulin superfamily : AGM3, 6 Integrin : LAD1 Glanzmann's thrombasthenia Junctional epidermolysis bullosa with pyloric atresia EDAR ( EDAR hypohidrotic ectodermal dysplasia ) PTCH1 ( Nevoid basal-cell carcinoma syndrome ) BMPR1A ( BMPR1A juvenile polyposis syndrome ) IL2RG ( X-linked severe combined immunodeficiency ) See also cell surface receptors v t e Extracellular ligand disorders Cytokine EDA Hypohidrotic ectodermal dysplasia Camurati–Engelmann disease Ephrin Craniofrontonasal dysplasia WNT Tetra-amelia syndrome TGF OFC 11 Fas ligand Autoimmune lymphoproliferative syndrome 1B Endothelin EDN3 Waardenburg syndrome IVb Hirschsprung's disease 4 Other DHH ( DHH XY gonadal dysgenesis ) BMP15 ( Premature ovarian failure 4 ) TSHB ( Congenital hypothyroidism 4 ) See also intercellular signaling peptides and proteins

It may be inherited in an X-linked recessive, autosomal recessive, or autosomal dominant manner depending on the genetic cause of the condition. ... The forms have similar signs and symptoms, however the the autosomal dominant form tends to be the mildest. Treatment of hypohidrotic ectodermal dysplasia may include special hair care formulas or wigs, measures to prevent overheating, removal of ear and nose concretions, and dental evaluations and treatment (e.g., restorations, dental implants, or dentures).

Less commonly, hypohidrotic ectodermal dysplasia has an autosomal dominant or autosomal recessive pattern of inheritance. Mutations in the EDAR , EDARADD , or WNT10A gene can cause either autosomal dominant or autosomal recessive hypohidrotic ectodermal dysplasia. Autosomal dominant inheritance means one copy of the altered gene in each cell is sufficient to cause the disorder.

It comprises three clinically almost indistinguishable subtypes with impaired sweating as the key symptom: Christ-Siemens-Touraine (CST) syndrome (X-linked), autosomal recessive (AR), and autosomal dominant (AD) HED, as well as a fourth rare subtype with immunodeficiency as the key symptom (HED with immunodeficiency) (see these terms).

Birth defect of the development of the brain Agenesis of the corpus callosum Specialty Neurology Agenesis of the corpus callosum ( ACC ) is a rare birth defect in which there is a complete or partial absence of the corpus callosum . It occurs when the development of the corpus callosum, the band of white matter connecting the two hemispheres in the brain , in the embryo is disrupted. The result of this is that the fibers that would otherwise form the corpus callosum are instead longitudinally oriented along the ipsilateral ventricular wall and form structures called Probst bundles . In addition to agenesis, other degrees of callosal defects exist, including hypoplasia (underdevelopment or thinness), hypogenesis (partial agenesis) or dysgenesis (malformation). [1] ACC is found in many syndromes and can often present alongside hypoplasia of the cerebellar vermis . When this is the case, there can also be an enlarged fourth ventricle or hydrocephalus ; this is called Dandy–Walker malformation . [2] Contents 1 Signs and symptoms 1.1 Associated brain anomalies 1.2 Associated syndromes and conditions 2 Causes 2.1 Ciliopathies: rare genetic disorders 2.2 Cocaine and other street drugs 3 Diagnosis 4 Treatment 5 Prognosis 6 Notable cases 7 Notes 8 External links Signs and symptoms [ edit ] MRI images of three patients in the sagittal plane.

Corpus callosum agenesis is a birth defect in which the structure that connects the two sides of the brain (the corpus callosum ) is partially or completely absent. This birth defect can occur as an isolated condition or combined with other cerebral abnormalities, including Arnold-Chiari malformation , Dandy-Walker syndrome , schizencephaly (clefts or deep divisions in brain tissue), and holoprosencephaly (failure of the forebrain to divide into lobes.) It may also occur as part of other diseases such as Aicardi syndrome , (which only affect girls, includes corpus callosum agenesis, and other problems) or Andermann syndrome or it can also be associated with malformations in other parts of the body, such as midline facial defects. Symptoms are vary from person to person. Many people with agenesis of the corpus callosum do not have any symptoms or the symptoms may range from subtle or mild to severe, depending on whether and which associated brain abnormalities are present. The exact cause is still unknown. Treatment usually involves management of symptoms and seizures if they occur.

Autosomal recessive spastic paraplegia type 74 is a rare, genetic, spastic paraplegia-optic atrophy-neuropathy-related (SPOAN-like) disorder characterized by childhood onset of mild to moderate spastic paraparesis which manifests with gait impairment that very slowly progresses into late adulthood, hyperactive patellar reflex and bilateral extensor plantar response, in association with optic atrophy and typical symptoms of peripheral neuropathy, including reduced or absent ankle reflexes, lower limb atrophy and distal sensory impairment. Reduced visual acuity and pes cavus are frequently reported.

Type Description Gene OMIM Mode of inheritance Incidence I mild Null COL1A1 allele 166200 autosomal dominant, 60% de novo [18] 1 in 30.000 [19] II severe and usually lethal in the perinatal period COL1A1 , COL1A2 , 166210 (IIA), 610854 (IIB) autosomal dominant, ~100% de novo [18] 1 in 40.000 [20] to 1 in 100.000 [19] III considered progressive and deforming COL1A1 , COL1A2 259420 autosomal dominant, ~100% de novo [18] 1 in 60.000 [19] IV deforming, but with normal sclerae most of the time COL1A1 , COL1A2 166220 autosomal dominant, 60% de novo [18] V shares the same clinical features of IV, but has unique histologic findings ("mesh-like") IFITM5 610967 autosomal dominant [18] [21] VI shares the same clinical features of IV, but has unique histologic findings ("fish scale") SERPINF1 610968 autosomal recessive [18] VII associated with cartilage associated protein CRTAP 610682 autosomal recessive [18] VIII severe to lethal, associated with the protein leprecan LEPRE1 , P3H1 610915 autosomal recessive IX PPIB autosomal recessive Type I [ edit ] Blue sclera in osteogenesis imperfecta Collagen is of normal quality but is produced in insufficient quantities. ... Most cases result in death within the first year of life due to respiratory failure or intracerebral hemorrhage Severe respiratory problems due to underdeveloped lungs Severe bone deformity and small stature Type II can be further subclassified into groups A, B, and C, which are distinguished by radiographic evaluation of the long bones and ribs. ... Thus far it seems to be limited to a First Nations people in Quebec . [25] Mutations in the gene CRTAP causes this type. [26] Type VIII [ edit ] OI caused by mutation in the gene LEPRE1 is classified as type VIII. [26] Type IX Osteogenesis imperfecta type IX (OI9) is caused by homozygous or compound heterozygous mutation in the PPIB gene on chromosome 15q22. [27] Type X Caused by homozygous mutation in the SERPINH gene on chromosome 11q13. [28] Type XI [ edit ] OI caused by mutations in FKBP10 on chromosome 17q21. [29] The mutations cause a decrease in secretion of trimeric procollagen molecules. ... Characterized by congenital bowing of the long bones, wormian bones, blue sclerae, vertebral collapse, and multiple fractures in the first years of life. [35] Others [ edit ] A family with recessive osteogenesis imperfecta has been reported to have a mutation in the TMEM38B gene on chromosome 9 . [36] This gene encodes TRIC-B, a component of TRIC, a monovalent cation -specific channel involved in calcium release from intracellular stores. ... PMID 22018338 . S2CID 30745040 . ^ Page 771 Archived 2013-06-08 at the Wayback Machine in: Chen, Harold (2006).

Depending on the genetic cause, OI may be inherited in an autosomal dominant (more commonly) or autosomal recessive pattern.

Progressive deafness with stapes fixation , also known as Thies Reis syndrome, is a form of conductive or mixed hearing loss caused by fixation of the stapes. The stapes is one of the tiny bones in the middle ear. It rests in the entrance to the inner ear, allowing sounds to pass to the inner ear. If it becomes fixated, sound waves cannot pass through to the inner ear, resulting in loss of hearing. This condition may be associated with a number of conditions, including otosclerosis , Paget's disease and osteogenesis imperfecta , or it may be found in isolation. It may also result from chronic ear infections ( otitis media with tympanosclerosis ).

A number sign (#) is used with this entry because this disorder is caused by mutation in the gene encoding mitochondrial cytochrome b (MTCYB; 516020). Description Histiocytoid cardiomyopathy, which was initially described by Voth (1962), goes by various names, including infantile xanthomatous cardiomyopathy (MacMahon, 1971), focal lipid cardiomyopathy (Bove and Schwartz, 1973), oncocytic cardiomyopathy (Silver et al., 1980), infantile cardiomyopathy with histiocytoid change (Ferrans et al., 1976), and foamy myocardial transformation of infancy (Yatani et al., 1988). The disorder is a rare but distinctive entity of infancy and childhood characterized by the presence of characteristic pale granular foamy histiocyte-like cells within the myocardium. It usually affects children younger than 2 years of age, with a clear predominance of females over males. Infants present with dysrhythmia or cardiac arrest, and the clinical course is usually fulminant, sometimes simulating sudden infant death syndrome (Andreu et al., 2000).

Deacon et al. (1974) described brother and sister with a form of infantile cardiomyopathy characterized by accumulation of lipid in the sarcoplasm of myocardial fibers. Only sporadic cases had been reported previously (Reid et al., 1968). In Deacon's cases onset was at birth and 4 weeks of age and death at 19 days and 4 months from congestive heart failure. Both had microcephaly. Severe mitochondrial changes were found in the myocardial fibrils in addition to the accumulation of neutral fat. The parents were thought to be nonconsanguineous. McKusick (2002) noted that these may be cases of infantile histiocytoid cardiomyopathy (500000).