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Preretinal vascular loops are a congenital malformation usually occurring in otherwise normal fundi. These anomalies consist of vessels, most commonly arteries, that spiral into the vitreous and return to the otherwise normal retinal vascular system. The authors present two members of a family with preretinal vascular loops and two members with other vascular anomalies. The inheritance pattern in this group is autosomal dominant.
Virgil Sydenstricker was a member of a notable American family which included authoress Pearl S. Buck and the eminent epidemiologist Edgar Sydenstricker. Dr. Sydenstricker's contributions in the fields of hematology and nutritional disease are legion. His landmark work in sickle cell anemia characterized a definite symptom complex with specific hematologic findings and inheritance pattern. He wrote on the complications of malnutrition and attempted to delineate the specific effects of individual nutritional factors. Dr. Sydenstricker and his associate H. M. Cleckley first described the syndrome of niacin deficiency encephalopathy. Today, the syndrome is still occasionally reported. Niacin deficiency should be considered when unexplained acute confusional states or neurologic deficits occur in the setting of malnutrition, antituberculous drug use, or chronic partial nutritional deficiency with acute increase in metabolic demand.
STUDY DESIGN: A retrospective review of clinical data was conducted. OBJECTIVES: To determine the characteristics of infantile scoliosis in Marfan syndrome and the response to treatment of patients with this condition. SUMMARY OF BACKGROUND DATA: No previous study has reported the features of this condition nor the effect of treatment on patients with this syndrome. METHODS: The data on all patients seen at one institution who had Marfan syndrome and scoliosis by age three were reviewed. Fourteen of the 600 patients from the group examined who had Marfan syndrome fit the above criteria. Skeletal and general features were studied. RESULTS: Thirteen of the 14 patients had no family history of Marfan syndrome, a finding which does not fit the usual autosomal dominant inheritance pattern. All 14 patients had exaggeration of the Marfan. All but one patient had cardiac valvular insufficiency that required repair by age 11. Thirteen patients had thoracic aortic aneurysm, 10 had lens dislocation, and eight had sternal deformity. Three patients had hip dislocations, two had pyloric stenosis, and two had dural ectasia. Motor delay was evidenced by onset of walking past 18 months in nine patients; three of these patients were never able to walk independently. One patient each died at ages 1, 3, 4, and 8 years; all others have survived to present (mean age, 13 years). The mean curve of the patients' spines at presentation was 38 degrees. Eleven curves were double major, two were thoracolumbar, and one was double thoracic. Brace wear did not halt curve progression in any of the nine patients for whom it was used. Instrumentation without fusion was used in three patients for a mean of 3 years, with best results in one nonkyphotic curve. Nine patients underwent instrumented fusion at a mean age of 6.6 years (range, 3-13 years). Mean curve correction was 51% (from 72 degrees to 34 degrees). Final mean curve was 54 degrees for a mean correction of 20% at the 5-year (average, 5.4 years) follow-up examination. Acute complications occurred in three patients, and five patients needed a second surgery for late complications. Causes for curve increase after surgery included growth and loss of fixation. CONCLUSIONS: In this most severe form of Marfan syndrome, bracing has a limited role and is only to be used if the curve is less than 40 degrees. Surgery should not be performed on a patient younger than four years of age because many patients with large curves before this age will succumb spontaneously to cardiac complications. Instrumentation without fusion should be considered only for patients with no significant kyphosis. Results of fusion are better for patients who are older than five years of age.
STUDY DESIGN: A review of current knowledge, clinical publications, and recent concepts of the causes of Stickler's syndrome was correlated with a clinical review of the condition at the Children's Hospital of Eastern Ontario, Canada. OBJECTIVES: To acquaint orthopedic spine surgeons with the natural history, associated anomalies, and high incidence of spinal deformity and scoliosis in children with Stickler's syndrome. SUMMARY OF BACKGROUND DATA: Stickler's syndrome is a hereditary, progressive arthro-ophthalmopathy with an autosomal dominant inheritance pattern. The estimated incidence is 1 in 10,000 people, which is slightly more common than Marfan syndrome. METHODS: The experience with Stickler's syndrome was reviewed in seven children, 2-15 years of age, with particular attention to the spinal abnormalities secondary to the connective tissue dysplasia. RESULTS: Six of the children had kyphosis or scoliosis, and four had wedging or flattening of the vertebrae or platyspondylia. In general, the spinal changes became more prominent in the older children with Stickler's syndrome, with the spinal vertebrae affected by the generalized epiphyseal dysplasia. The treatment of scoliosis and kyphosis is no different in children with Stickler's syndrome. The most difficult aspect is in diagnosing the condition. CONCLUSIONS: The importance of recognizing the syndrome is to allow for the investigation and treatment of the many other associated connective tissue disorders associated with Stickler's syndrome, such as the high incidence of retinal detachment, mitral valve prolapse, and mandibular hypoplasia that may result in problems with anesthesia should the spine require surgical stabilization.
STUDY DESIGN: Classic cases of Scheuermann disease in male monozygotic twins are reported. OBJECTIVES: To report classic cases of Scheuermann disease or Scheuermann kyphosis in male monozygotic twins, and to discuss the previous two cases of classic Scheuermann disease in monozygotic twins and the genetic etiology theory of Scheuermann kyphosis. SUMMARY OF BACKGROUND DATA: The etiology of Scheuermann disease remains unclear. Both genetic and mechanical factors or a combination of the two have been postulated to explain Scheuermann disease. The genetic etiology hypothesis has been explained by an autosomal dominant inheritance pattern. In support of this genetic etiology hypothesis, two cases of Scheuermann disease in monozygotic twins have been reported in the English literature. METHODS: The criteria of Sørensen and Sachs et al were used to diagnose Scheuermann kyphosis. Clinical examination and lateral spinal radiographs were performed on a male monozygotic twin. Both parents were clinically investigated for signs of a kyphotic deformity. RESULTS Scheuermann disease was noted in both patients at the same vertebral levels. The Cobb angle of the kyphosis was 74 degrees and 48 degrees, respectively. Clinical examination of both parents did not show any kyphotic abnormality. CONCLUSIONS: These cases of classic Scheuermann disease in monozygotic male twins support the theory that there is a genetic contribution in classic Scheuermann disease.
A new class of glutathione S-transferase enzymes named omega (GSTO) has been recently identified and shown to be expressed in a wide range of human tissues. A genetic polymorphism of the GSTO1 gene causing an alanine-to-aspartate (A140D) substitution in amino acid 140 produces a variant with lowered enzyme activities in the biotransformation of inorganic arsenic, a common contaminant of drinking water in many regions of the world and a well-known carcinogen. In order to investigate the role of GSTO1 inheritance pattern on thyroid cancer risk we used a polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP)-sequencing approach to compare the genotypes of 173 (87 women, 86 men; 18-81 years old; 47+/-18 years old) healthy control individuals with those of 145 patients with thyroid nodules (84 women, 61 men; 17-81 years old; 49+/-14 years old) including 17 follicular carcinomas, 76 papillary carcinomas, 21 follicular adenomas and 31 multinodular goiters. The incidence of GSTO1 variants was similar in the control population and population with the benign and malignant nodules. There was no association between genotype and the patients' clinical features, tumour parameters of aggressiveness at diagnosis or behaviour during follow-up. We conclude that GSTO1 variants do not influence the risk for thyroid nodules or their pathologic and clinical characteristics.
PURPOSE OF REVIEW: The study of inherited renal sodium (Na) transport disorders has greatly benefited from the use of new molecular biology research tools. This review discusses the recent findings that have expanded our knowledge and may impact clinical decision-making. RECENT FINDINGS: The genetic and molecular biology diagnostic tools have to a large extent validated conclusions drawn from physiologic studies that documented suppressed or enhanced Na transport in specific distal nephron segments in various disorders. However, many surprises were also encountered. In several conditions, no mutation in the Na transporter itself was found despite apparent dysfunction of the transporter. Further search has led to discovery of additional mechanisms. Some involve mutations in other transporters, especially potassium (K) and chloride (Cl) channels, which secondarily affect function of the Na transporter by altering electrochemical gradients across the cell membrane. Examples include certain types of Bartter syndrome. In other patients, search for mechanism has led to discovery of novel physiologic regulatory pathways that, if abnormal, will lead to up- or downregulation of an Na transporter. Examples include some types of Bartter syndrome and Gordon syndrome. Genetic diagnosis has also revealed hitherto unexplained phenotypic heterogeneity between patients carrying the same mutation, implying a contributory role for other factors. SUMMARY: Genetic and molecular diagnosis will have an expanding role in the understanding and management of the Na transport disorders. Predicting prognosis and inheritance pattern, as well as treatment plans will in the future be based on genetic diagnosis.
At least three types of congenital nonhemolytic unconjugated hyperbilirubinemias, including the rare Crigler-Najjar (CN) diseases (Types I or II) and Gilbert's syndrome (affecting 6% of the population) are associated with either absent or reduced hepatic UDP-glucuronosyltransferase (transferase) activity towards the potentially toxic endogenous acceptor, bilirubin. Here, we review the biochemical studies associated with these deficiencies. Accumulated evidence from studies with an animal model of CN Type I syndrome, the Gunn strain of hyperbilirubinemic rats, suggested that multiple isozymes are absent. These confounding observations have been clarified by a flurry of reports which have revealed the molecular basis for the complex disease phenotype in the Gunn rat and by the isolation and description of a novel human gene complex, UGT1, which encodes multiple and independently-regulated transferase isozymes that contain identical carboxyl terminal regions (246 amino acids). Finally, we discuss the implications of the gene organization and genetic defects determined for four different CN Type I individuals as a basis for a model which explains the inheritance pattern and genotypes of other familial unconjugated hyperbilirubinemias.
Synostoses at the elbow joint are rare. The literature divides them into three groups based on the nature of bony ankylosis; the commonest are humeroradial synostoses. Approximately 150 cases have been reported. There are 29 reported cases of humeroradioulnar synostosis and five of humeroulnar synostosis. An anatomical classification was previously described for humeroradial synostoses. Due to significant phenotypic variability we believe a classification based solely on anatomical characteristics will in some cases be misleading. No classification exists for humeroradioulnar and humeroulnar synostosis. By re-examining the literature we have produced a combined classification for all elbow synostoses which more accurately predicts causes. Congenital elbow synostoses often cause little functional disability. Treatment by soft tissue release and osteotomy has been attempted, but although range of movement is initially, improved re-ossification is the norm. Investigation is more complicated and may be helped by classification which identifies syndrome association, risk of organ anomaly, and inheritance pattern.
Classical lissencephaly and double cortex are genetic neuronal migration disorders associated with mental retardation and epilepsy. In classical lissencephaly, the six-layered cortex is replaced by a four layered structure lacking normal gyri or sulci. In double cortex, a second layer of cortical neurons underlies a normal cortex. A mutation in LIS1 or doublecortin can lead to either classical lissencephaly or double cortex, but because LIS1 is autosomal and doublecortin is X-linked (on the X chromosome), the disease inheritance pattern and risk of recurrence for the two genes are distinct. Mutation analysis for LIS1 and doublecortin is essential in determining the etiology of the disease in patients and may be helpful in determining the recurrence risk in families.
Two siblings are presented with hypoplastic left heart syndrome and symmetrical postaxial polydactyly affecting upper and lower limbs. This association has not been previously documented. This appears to represent a newly recognized syndrome. The inheritance is likely to be autosomal recessive, but other inheritance patterns cannot be excluded at present.
A 15 year old girl with the Myhre type growth-mental retardation syndrome is described. This is the first female case reported in the literature. The inheritance pattern of this condition is not clear.
The complex multifactorial inheritance pattern of systemic lupus erythematosus in various murine models has been dissected via both classic genetic analysis and the use of modern technologies in genomic manipulation. Current information suggests that lupus may be mediated by a multitude of genetic abnormalities that impact on specific checkpoints in a three-step pathogenic pathway. These steps are as follows: loss of immunologic tolerance to nuclear antigens; the transition to pathogenic autoimmunity; and end-organ targeting. The identities of the genes that are responsible for transition between the specific steps of the pathway are still unknown and will require further study. However, several recent findings have provided insights into specific elements in each stage of lupus. These findings suggest that mouse models of lupus may provide valuable insights into the genetic basis of human systemic lupus erythematosus.
Recent advances in genetics tend to center on the discoveries of molecular biology. A disease is first linked to a region on a chromosome, a gene is later cloned, or a candidate gene identified, point mutations described, phenotype-genotype correlations made, and rationales for treatment proposed. Several neuro-ophthalmological diseases have recently been studied in this way; including Leber's hereditary optic neuropathy and other mitochondrial diseases, autosomal dominant (Kjer) optic atrophy, Wolfram syndrome, or DIDMOAD (diabetes insipidus, diabetes mellitus, optic atrophy, and deafness), Usher syndrome, neurofibromatosis types I and II, and two disorders of the paired box genes: aniridia and Waardenburg's syndrome. Apart from molecular biology there are still some new disease entities being described and new inheritance patterns identified for some syndromes, such as periodic alternating nystagmus.
Complete agenesis of the bony labyrinth, first described by Michel, represents the most severe form of inner ear defect. A search of the literature yielded only one report of this rare anomaly, affecting two siblings. Three familial cases of bilateral inner ear aplasia are reported here, and the probable inheritance pattern of this condition is discussed.
OBJECTIVE: To document isolated round window atresia and to discuss its impact on current theories of inner ear function. PATIENTS AND STUDY DESIGN: Retrospective analysis of isolated round window atresia suggesting an autosomal dominant inheritance pattern and review of current concepts of cochlear macromechanics. SETTING: Tertiary referral center. RESULTS: The unexpected finding of isolated round window atresia in two female patients of the same family was confirmed intraoperatively as well as postoperatively using high-resolution computed tomography. The current audiograms and the review of the literature highlight a mixed, but predominantly conductive, hearing impairment with thresholds at 30 to 40 dB. Implying that there is no pressure release mechanism for inner ear fluid displaced by the stapes footplate, a total conductive hearing loss would be expected. CONCLUSIONS: The rare finding of round window atresia can be overlooked at surgery because of insufficient exposure of the round window niche. High-resolution computed tomography confirms the round window obliteration. It seems that an alternative way of cochlear stimulation takes place besides the concept of fluid bulk shifting. Surgery seems not to guarantee favorable results.
PURPOSE: Keratoconus is a corneal dystrophy with an incidence of 1 in 2000 and a leading cause for cornea transplantation in Western developed countries. Both clinical observations and segregation analyses suggest a major role for genes in its pathogenesis. It is genetically heterogeneous, most commonly sporadic, but inherited patterns with recessive or dominant modes have also been reported. We studied a four-generation autosomal-dominant pedigree to identify disease loci for keratoconus. METHODS: A two-stage genome-wide scan was applied to 27 family members. First linkage analysis was performed with 343 microsatellite markers along the 22 autosomal chromosomes at approximately 10 cM density. This was followed by fine mapping at approximately 2 cM density, in regions suggestive of linkage. Multipoint linkage analysis was performed using GeneHunter2. RESULTS: Evidence of suggestive linkage from the initial scan was observed at the 82 to 112 cM region of chromosome 5q14.1-q21.3 with a maximum lod score (LOD) of 3.48 (penetrance = 0.5). Fine mapping by testing an additional 11 microsatellite markers at 1 to 3 cM intervals revealed a narrower and higher peak (99-119 cM) with LOD 3.53. By analysis of the recombination of haplotypes, the putative locus of keratoconus was further narrowed to a 6 cM region (8.2 Mbp physical distance) between markers D5S2499 and D5S495. CONCLUSION: These results indicate a promising new locus for keratoconus in this pedigree. Because of the heterogeneous nature of keratoconus, this locus may be specific to familial autosomal-dominant keratoconus. Nevertheless, the identification of this locus may provide new insights into the pathogenesis of keratoconus.
PURPOSE OF REVIEW: To integrate knowledge on the embryologic and molecular basis of optic fissure closure with clinical observations in patients with uveal coloboma. RECENT FINDINGS: Closure of the optic fissure has been well characterized and many genetic alterations have been associated with coloboma; however, molecular mechanisms leading to coloboma remain largely unknown. In the past decade, we have gained better understanding of genes critical to eye development; however, mutations in these genes have been found in few individuals with coloboma. CHD7 mutations have been identified in patients with CHARGE syndrome (coloboma, heart defects, choanal atresia, retarded growth, genital anomalies, and ear anomalies or deafness). Animal models are bringing us closer to a molecular understanding of optic fissure closure. SUMMARY: Optic fissure closure requires precise orchestration in timing and apposition of two poles of the optic cup. The relative roles of genetics and environment on this process remain elusive. While most cases of coloboma are sporadic, autosomal dominant, autosomal recessive, and X-linked inheritance patterns have been described. Genetically, colobomata demonstrate pleiotropy, heterogeneity, variable expressivity, and reduced penetrance. Coloboma is a complex disorder with a variable prognosis and requires regular examination to optimize visual acuity and to monitor for potential complications.