Deletion in blood mitochondrial DNA in Kearns-Sayre syndrome

Mitochondrial DNA deletions have been described in the Kearns-Sayre syndrome (KSS) and the Pearson's marrow-pancreas syndrome. In some cases, the same 4,977-bp deletion has been identified in these two very different diseases. Therefore, it is not currently possible to predict the clinical phenotype from the size or location of the deletion. Instead, differential tissue distribution of the deletion has been implicated as one possible determinant of phenotype. In particular, in KSS the deletions have not been detected by Southern blotting in the blood, whereas in Pearson's syndrome they are easily detectable. We describe here an 11-y-old boy with clinically characteristic KSS and a 7.4-kb mitochondrial DNA deletion between nucleotides 7,194 and 14,595. Southern blotting reveals that 75% of the mitochondrial DNA molecules from his peripheral blood have this deletion. This case blurs further the molecular distinction between the KSS and Pearson's marrow-pancreas syndrome, questioning whether tissue distribution is a sufficient explanation for the very different phenotypes of these disorders.

The Zavanelli maneuver: a different perspective

Some obstetricians recommend the Zavanelli maneuver to resolve shoulder dystocia. Descriptions in the literature report an almost automatic ease in performance of the maneuver. We report a case of severe shoulder dystocia in which management with the Zavanelli maneuver and immediate cesarean was extremely difficult. The procedure involved exact reversal of all the cardinal movements of labor, and the delivery required terbutaline, general anesthesia, and added personnel to ensure successful extraction of the fetus. A delivery requiring the Zavanelli maneuver can be difficult to perform and may be worsened by insufficient personnel and inexact reversal of all the cardinal movements of labor.

Fellowships and career development in dysmorphology and clinical genetics

This article sets forth some guiding principles for the initiation of a productive and satisfying academic career as a clinical researcher in the areas of dysmorphology, teratology, and clinical genetics. It assumes that the fellow in dysmorphology and clinical genetics is genuinely committed to the pursuit of a career in this area, but these general principles are certainly relevant to other medical specialties. It is important for pediatricians to consider careers in this area because the need for dysmorphologists and clinical geneticists will continue to increase during the foreseeable future, and the current opportunities for such training are limited.

Secondary flow in the human common carotid artery imaged by MR angiography

The blood flow in arteries affects both the biology of the vessels and the development of atherosclerosis. The flow is three-dimensional, unsteady, and difficult to measure or to model computationally. We have used phase-shift-based magnetic resonance angiography to image and measure the flow in the common carotid arteries of a healthy human subject. There was curvature of the vessels and thin-slice dynamic flow imaging showed evidence of the presence of secondary motions. Flexing the cervical spine straightened the vessels and reduced the asymmetry of the flow.

Collagen, genes and the skeletal dysplasias on the edge of a new era: a review and update

This article reviews the newly described biochemical (type I and II collagen) abnormalities and specific gene defects in the skeletal dysplasias. The model of the collagen molecule is described and how collagen is processed from procollagen, where and how abnormalities occur, and the types of abnormalities produced (quantitative and qualitative). The only known type I collagen defects producing skeletal dysplasias--osteogenesis imperfecta, as well as the 'family' of established type II collagen disorders--achondrogenesis type II, hypochondrogenesis and spondyloepiphyseal dysplasia congenita are discussed. Finally, using case presentations, the practical approach to these disorders is shown. The importance of these investigations and the subsequent reevaluation of the clinical and radiological findings of specifically delineated skeletal dysplasias are discussed.

Radiological findings in Hallermann-Streiff syndrome: report of five cases and a review of the literature

Hallermann-Streiff syndrome (HSS) is a rare disorder with an associated constellation of radiological findings that may aid in the diagnosis of affected individuals. We reviewed the skeletal surveys of 5 affected individuals and noted some characteristic and constant findings. Radiological findings can include a large, poorly ossified skull with decreased ossification in the sutural areas. There was an increase in the number of Wormian bones. Severe mid-facial hypoplasia was present along with a prominent nasal bone. The skull films also showed an abnormally obtuse or nearly straight gonial angle. The teeth appeared small. The long bones were thin and gracile in appearance and often showed poor demarcation of the cortex from the medullary portion. Abnormal bowing of the radius and ulna was seen neonatally in 2 cases. There was widening at the metaphyseal ends of the long bones. The ribs were thin, but normal in length. The vertebral bodies were noted to be small and 3 cases had platyspondyly. There was a decreased number of sternal ossification enters. The metacarpals were also thin and gracile in appearance with metaphyseal widening. We conclude that these characteristic radiological findings in the newborn with HSS can aid in the diagnosis, and a skeletal survey in suspected individuals may be valuable in confirming the diagnosis.

Identification of fetal problems associated with anticonvulsant usage and maternal epilepsy

This article reviews the general approach for assessing teratogenic risks related to fetal exposure, concentrating on the specific patterns associated with anticonvulsant usage and maternal epilepsy. Major anomalies that might be detected prenatally are presented, as well as the patterns of minor anomalies (syndromes) that might be detected at birth or later. Each of the specific drugs used in the treatment of epilepsy is reviewed in detail. In addition, recent information concerning genetically determined variations in the metabolism of antiepileptic drugs is discussed in light of how genetic factors might relate to teratogenicity.

Localization of the gene encoding the GABAA receptor beta 3 subunit to the Angelman/Prader-Willi region of human chromosome 15

Deletions of the proximal long arm of chromosome 15 (bands 15q11q13) are found in the majority of patients with two distinct genetic disorders, Angelman syndrome (AS) and Prader-Willi syndrome (PWS). The deleted regions in the two syndromes, defined cytogenetically and by using cloned DNA probes, are similar. However, deletions in AS occur on the maternally inherited chromosome 15, and deletions in PWS occur on the paternally derived chromosome 15. This observation has led to the suggestion that one or more genes in this region show differential expression dependent on parental origin (genetic imprinting). No genes of known function have previously been mapped to this region. We show here that the gene encoding the GABAA (gamma-aminobutyric acid) receptor beta 3 subunit maps to the AS/PWS region. Deletion of this gene (GABRB3) was found in AS and PWS patients with interstitial cytogenetic deletions. Evidence of beta 3 gene deletion was also found in an AS patient with an unbalanced 13;15 translocation but not in a PWS patient with an unbalanced 9;15 translocation. The localization of this receptor gene to the AS/PWS region suggests a possible role of the inhibitory neurotransmitter GABA in the pathogenesis of one or both of these syndromes.

Deletion of 20p 11.23----pter with normal growth hormone-releasing hormone genes

Using a molecular analysis of the DNA from a patient with a deletion of chromosome 20 [46,XX,del(20)(p 11.23)], we have excluded the growth hormone-releasing hormone (GHRH) gene from the region 20p11.23----pter. The patient had minor facial anomalies. Rieger eye anomaly, a congenital heart defect, severe failure to thrive, and a neurosecretory problem in growth hormone (GH) secretion. Since the GHRH gene was previously mapped to chromosome 20, we used molecular genetic methods to determine whether the growth abnormalities were due to the deletion of this gene. DNAs of the patient and 2 normal control subjects were analyzed by quantitative Southern blotting using a DNA probe for the GHRH gene and 2 reference DNA probes mapping to chromosome 21. The GHRH gene was found to be present in 2 copies in the patient. This indicates that the gene for GHRH maps to the region outside the patient's deletion, in 20p11.23----qter. Furthermore, our results suggest that genes other than GHRH on 20p are important for developmental steps leading to normal neurosecretory function of GH and may also be involved in generating Rieger eye anomaly. Finally, GH deficiency and Rieger eye anomaly should be sought in other patients with deletions of 20p.

Congenital gastric teratoma in Wiedemann-Beckwith syndrome

Wiedemann-Beckwith syndrome (WBS) may be associated with abdominal tumors, including Wilms tumor, adrenocortical carcinoma, hepatoblastoma, gonadoblastoma, rhabdomyosarcoma, and neuroblastoma. We report on a newborn infant with WBS and a congenital teratoma of the stomach. This is the sole report of any teratoma being associated with WBS and also the first report of a tumor present at birth and visible prenatally in WBS. At birth this infant boy had the diagnostic findings of WBS with macroglossia, ear lobule creases and pits, nevus flammeus, and omphalocele, and an abdominal mass. Abnormalities were detected prenatally when ultrasound examination showed placental overgrowth, polyhydramnios, omphalocele, and posterior abdominal calcifications. Resection of the mass and partial gastrectomy were performed at age 10 days; histologic study showed an immature grade-II teratoma containing a mixture of mature and immature tissues from all germ layers. Results of cytogenetic studies of blood and teratoma were normal (46,XY). This congenital gastric teratoma in a newborn boy with classical WBS may represent either a tumor or an included twin. We discuss its implications for the association of WBS with neoplasia and monozygotic (MZ) twinning, review various neoplasias associated with WBS, and consider pathogenetic mechanisms.

Analysis of the chondroitin sulfate proteoglycan core protein (CSPGCP) gene in achondroplasia and pseudoachondroplasia

Achondroplasia and pseudoachondroplasia are autosomal dominant skeletal dysplasias resulting in short-limbed dwarfism. Histologic and ultrastructural studies of the cartilage in pseudoachondroplasia and in homozygous achondroplasia have suggested a structural abnormality in chondroitin sulfate proteoglycan (CSPG), a major structural protein in the extra-cellular matrix. The gene encoding CSPG core protein (CSPGCP) is thus a logical "candidate gene" for analysis in these conditions. cDNA probes encoding CSPGCP were used to identify restriction fragment length polymorphisms (RFLPs) in DNA from a panel of control individuals. No gross alterations at the CSPGCP locus were noted in DNA from 37 individuals with achondroplasia and 5 individuals with pseudoachondroplasia. In addition, allelic frequencies of the RFLPs were not significantly different among controls and patients with either condition. In one three-generation family with achondroplasia, close linkage of the CSPGCP locus and the skeletal dysplasia was excluded using a Bgl II polymorphism. Similarly, in a three-generation family with pseudoachondroplasia, the CSPGCP gene was not tightly linked to the disease phenotype. These results indicate that mutations at the chondroitin sulfate proteoglycan core protein locus do not cause achondroplasia or pseudoachondroplasia in these families.

Diagnosis and management of infantile marfan syndrome

Marfan syndrome is infrequently diagnosed early in infancy. The experience of the authors with 22 severely affected infants diagnosed as having Marfan syndrome in the first 3 months of life is described and the literature on 32 additional infants with Marfan syndrome is reviewed. It was found that serious cardiac pathology (82% of the patients described in the article, 94% of those described in the literature) may be present at birth, and that congenital contractures (64% of our cases, 47% of literature cases) are often an associated finding. Other useful clinical findings included arachnodactyly, dolichocephaly, a characteristic facies, a high-arched palate, micrognathia, hyperextensible joints, pes planus, anterior chest deformity, iridodenesis, megalocornea, and dislocated lenses. Echocardiography was useful as a noninvasive method for defining the extent of cardiovascular involvement and following its course. Characteristic cardiac findings in early life included mitral valve prolapse, valvular regurgitation, and aortic root dilation. Cardiac function ranged from normal to poor, with a tendency to worsen. Of the 22 cases 3 infants died during the first year of life. Morbidity and mortality may be high when Marfan syndrome is diagnosed during infancy, and prompt recognition of this phenotype can facilitate management and counseling. Most such severe cases appear to be due to a sporadic mutation in a single germ cell of one parent. Many familial cases may have milder manifestations, be more difficult to detect during infancy, and have a better prognosis.

Central nervous system malformations in the CHARGE association

Of 144 patients with the CHARGE association (literature 136, new patients 8), 47 (33%) had either a postmortem examination (30) or computerized axial tomography scan (17) of the head. Twenty-six of 47 (55%) had definite central nervous system (CNS) malformations; arhinencephaly, with or without other defects (11), holoprosencephaly (2), holoprosencephaly with arhinencephaly (1), other forebrain defects (3), hindbrain defects (3), or other defects (6). The presence of CNS malformation was most strongly associated with choanal atresia. This review demonstrates a predominance of forebrain anomalies, particularly arhinencephaly and holoprosencephaly, which may provide a clue to the mechanism of abnormal morphogenesis involved in CHARGE association.

Microphthalmia and chorioretinal lesions in a girl with an Xp22.2-pter deletion and partial 3p trisomy: clinical observations relevant to Aicardi syndrome gene localization

We present a 4-year-old girl with a maternally derived, unbalanced X;3 translocation resulting in partial Xp monosomy and partial 3p trisomy. She had chorioretinal defects, developmental delay, infantile seizures, and microphthalmia. These findings initially suggested a diagnosis of Aicardi syndrome. However, she had a normal-appearing corpus callosum on CT and magnetic resonance imaging scans of the brain and her retinal findings were not typical for Aicardi syndrome. This represents the 6th reported example of microphthalmia associated with an Xp22 chromosome abnormality. Four of these individuals also had features suggestive of focal dermal hypoplasia (FDH), which was not evident in our patient. The available evidence supports the hypothesis that gene disruption at Xp22 may lead to findings similar to those seen in Aicardi syndrome and FDH, both of which are believed to be X-linked dominant male lethal conditions.

Reactions of mothers and medical professionals to a film about Down syndrome

Parents, genetic counselors, and nurses were shown an 18-minute video-taped discussion involving parents of persons with Down syndrome and were asked to complete an evaluation. Some of the statistically significant differences were as follows: 89% of mothers believed that the film was an accurate portrayal of parental attitudes compared with 14% of the genetic counselors and 40% of the nurses; 48% of genetic counselors believed that problems outweigh the benefits in parenting a child with Down syndrome, but 94% of mothers and 83% of nurses thought that the benefits predominated; and 56% of genetic counselors believed that parents of a child with Down syndrome would choose to abort a subsequent affected fetus while only 8% of parents and 10% of nurses agreed. It is important that medical professionals have a balanced and accurate view of the impact of Down syndrome on families.

Posterior nuchal cystic hygroma

When cystic hygroma is detected antenatally, the prognosis is usually poor, and intrauterine or neonatal death are common. This seems especially true for Turner syndrome (the largest etiologic group associated with cystic hygroma) and the lethal multiple pterygium syndromes. However, some fetuses with Turner syndrome, and also with certain other diagnoses, had a good outcome, and further study of these conditions is required before more definite prognostic indicators and risk figures will be available. Increasing numbers of syndromes are being reported in association with fetal cystic hygroma, and lymphedema may be a common element in their pathogenesis. Mild, short-lived, or otherwise uncomplicated jugular lymphatic obstruction may be a cause of the neck webbing seen in the Noonan, familial pterygium colli, and distichiasis-lymphedema syndromes. With earlier and more widespread fetal ultrasonography, and more sensitive techniques, a greater number of resolving fetal cases may be reported. This may clarify the natural history and provide prospective criteria for the conditions that have better prognoses. The associated conditions include autosomal dominant and recessive genetic traits. Careful ultrasound study for other malformations, polyhydramnios and fetal growth parameters, a fetal karyotype, and, if appropriate, pathologic examination are required to determine the etiology and recurrence risk. The parents should be asked about exposure to alcohol or other agents and should be examined for signs of pterygium colli or Noonan syndrome. If the decision is made to continue the pregnancy, and there is doubt about the natural history and prognosis, multi-disciplinary supervision should include social services, neonatology, pediatric surgery, cardiology, and genetics specialties when indicated.

Clinical approach to prenatal detection of human structural defects

Tremendous advances in prenatal diagnosis have allowed clinicians to recognize a variety of structural defects in the developing fetus. Guidelines for fetal ultrasonography and an approach to fetal evaluation are outlined. The developmental morphologic approach is emphasized as a way of categorizing congenital anomalies whether they are detected during prenatal or postnatal life. The use of this approach for diagnosing and managing fetal malformation syndromes is illustrated.

Studies of type I collagen in osteogenesis imperfecta

We used the results of skin fibroblast type I collagen analysis to improve the accuracy of diagnosis and genetic counseling for six patients with osteogenesis imperfecta. The fibroblasts of two patients with osteogenesis imperfecta type I synthesized a reduced quantity of qualitatively normal type I procollagen. Another patient with osteogenesis imperfecta type I had two populations of type I collagen molecules, one apparently normal and the other with a substitution of cysteine for glycine in the triple helical domain. Three sporadic cases with osteogenesis imperfecta types II, III, and IV were studied; in each proband a normal and an abnormal overmodified population of type I collagen molecules were demonstrated, and parental collagens were normal in the two available patients. These results indicated that the probands were heterozygous for new dominant mutations and assisted our genetic counseling, especially in osteogenesis imperfecta types II and III, which were formerly believed to be inherited in an autosomal recessive fashion. The results could not exclude parental germ line mosaicism for a new dominant mutation, which has resulted in recurrence in siblings of some patients with osteogenesis imperfecta, so prenatal diagnosis was therefore offered for future pregnancies. Analysis of chorionic villus cell collagen may facilitate antenatal diagnosis in selected cases, and the study of a larger number of patients may allow correlation of the biochemical defects with the natural history and prognosis.

Angelman syndrome: three molecular classes identified with chromosome 15q11q13-specific DNA markers

Angelman syndrome (AS) and Prader-Willi syndrome (PWS) share a cytogenetic deletion of chromosome 15q11q13. To determine the extent of deletion in AS we analyzed the DNA of 19 AS patients, including two sib pairs, with the following chromosome 15q11q13--specific DNA markers: D15S9-D15S13, D15S17, D15S18, and D15S24. Three molecular classes were identified. Class I showed a deletion of D15S9-D15S13 and D15S18; class II showed a deletion of D15S9-D15S13; and in class III, including both sib pairs, no deletion was detected. These molecular classes appear to be identical to those observed in PWS. High-resolution cytogenetic data were available on 16 of the patients, and complete concordance between the presence of a cytogenetic deletion and a molecular deletion was observed. No submicroscopic deletions were detected. DNA samples from the parents of 10 patients with either a class I or a class II deletion were available for study. In seven of the 10 families, RFLPs were informative as to the parental origin of the deletion. In all informative families, the deleted chromosome 15 was observed to be of maternal origin. This finding is in contrast to the paternal origin of the deletions in PWS and is currently the only molecular difference observed between the two syndromes.

The achondroplasia gene is not linked to the locus for neurofibromatosis 1 on chromosome 17

We have investigated genetic linkage of von Recklinghausen neurofibromatosis (NF1) and achondroplasia (ACH) using chromosome-17 markers that are known to be linked to NF1. Physical proximity of the two loci was suggested by the report of a patient with mental retardation and the de novo occurrence of both NF1 and ACH. Since the chance of de novo occurrence of these two disorders in one individual is 1 in 600 million, this suggested a chromosomal deletion as a single unifying molecular event and also that the ACH and NF1 loci might be physically close. To test this, we performed linkage analysis on a three-generation family with ACH. We used seven DNA probes that are tightly linked to the NF1 locus, including DNA sequences that are known to flank the NF1 locus on the centromeric and telomeric side. We detected two recombinants between the ACH trait and markers flanking the NF1 locus. In one recombinant, the flanking markers themselves were nonrecombinant. Multi-point linkage analysis excluded the ACH locus from a region surrounding the NF1 locus that spans more than 15 cM (lod score less than -2). Therefore, analysis of this ACH pedigree suggests that the ACH locus is not linked to the NF1 locus on chromosome 17.

Distal femoral physeal problem fractures

Treatment options in the past for distal femoral physeal fractures have varied from closed reduction to open reduction with internal fixation to balanced skeletal traction. In this study, ten patients with distal femoral physeal fractures treated with closed reduction and casting or skeletal traction are reviewed. Seven fractures lost position in comparison with original reduction films. Nine patients developed subsequent deformity. No consensus exists regarding the use of open versus closed treatment with internal fixation. This review of closed treatment yielded a high rate of unacceptable results. Initial anatomic reduction with rigid fixation of physeal injuries about the ankle has been demonstrated to decrease the incidence of growth deformity. The authors' experience and a review of the literature suggest that a similar approach is applicable to distal femoral physeal fractures.