Biomedical subjects
W B Dobyns
Publications and source records attributed to W B Dobyns.
Diagnostic criteria for Walker-Warburg syndrome.
Walker-Warburg syndrome (WWS) is an autosomal recessive disorder manifest by characteristic brain and eye malformations. We reviewed data on 21 of our patients and an additional 42 patients from the literature. From this review, we expand the phenotype to include congenital muscular dystrophy (CMD) and cleft lip and/or palate (CLP), and revise the diagnostic criteria. Four abnormalities were present in all patients checked for these anomalies: type II lissencephaly (21/21), cerebellar malformation (20/20), retinal malformation (18/18), and CMD (14/14). We propose that these comprise necessary and sufficient diagnostic criteria for WWS. Two other frequently observed abnormalities, ventricular dilatation with or without hydrocephalus (20/21) and anterior chamber malformation (16/21), are helpful but not necessary diagnostic criteria because they were not constant. All other abnormalities occurred less frequently. Congenital macrocephaly with hydrocephalus (11/19) was more common than congenital microcephaly (3/19). Dandy-Walker malformation (10/19) was sometimes associated with posterior cephalocele (5/21). Additional abnormalities included slit-like ventricles (1/21), microphthalmia (8/21), ocular colobomas (3/15), congenital cataracts (7/20), genital anomalies in males (5/8), and CLP (4/21). Median survival in our series was 9 months. A related autosomal recessive disorder, Fukuyama congenital muscular dystrophy, consists of similar but less severe brain changes and CMD. It differs from WWS because of consistently less frequent and severe cerebellar and retinal abnormalities. We think that WWS is identical to "cerebro-oculo-muscular syndrome" and "muscle, eye, and brain disease."
Acute inflammatory demyelinating polyradiculoneuropathy (Guillain-Barré syndrome) after immunization with Haemophilus influenzae type b conjugate vaccine.
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Agenesis of the corpus callosum and gyral malformations are frequent manifestations of nonketotic hyperglycinemia.
A 2-week-old infant who presented with myoclonic encephalopathy had biochemical abnormalities consistent with nonketotic hyperglycinemia. Cranial CT showed agenesis of the corpus callosum, gyral malformation, and ventricular enlargement. Similar brain abnormalities occurred in 9 of 15 previously reported patients. Including this patient, agenesis of the corpus callosum appeared in 6 of 15 patients, gyral malformation in 6 of 14, ventricular enlargement in 5 of 15, and cerebellar hypoplasia in 2 of 16. Nonketotic hyperglycinemia thus joins a growing list of inborn errors of metabolism associated with brain malformations.
The neurogenetics of lissencephaly.
A comprehensive approach to diagnosis of patients with lissencephaly using clinical, CT and MRI scan, and sometimes other laboratory data will allow a specific diagnosis to be made in a large majority of patients. The most common diagnoses in order of decreasing frequency will probably prove to be WWS, MDS, and ILS. The remainder constitute a heterogeneous group. Both diagnosis and counseling have been modified by several recent and important advances. Diagnostic criteria for WWS have been revised. Several molecular probes have been located within the MDS critical region in chromosome band 17p13.3. Prenatal diagnosis should prove to be reliable in both WWS and MDS.
Familial pericentric and paracentric inversions of chromosome 1.
We investigated 33 individuals (21 carriers) from one family with a pericentric inversion involving a large part of chromosome 1 (1p36.1----1q32). In addition, we investigated 15 individuals (10 carriers) from another family with a paracentric inversion of a small part of chromosome 1 (1p32----1p36.1). In each family, the index patient was ascertained because three miscarriages had occurred. Each carrier of these inversions was phenotypically normal. If the miscarriages of the index patients are excluded, the frequency of recognized miscarriages among the carriers of childbearing age was 9% (4 of 46) for the family with pericentric inversion and 17% (4 of 23) for the family with paracentric inversion. One of the pericentric inv(1) carriers had had a stillborn daughter. The carriers of the pericentric inversion who were of childbearing age had 41 children; carriers of the paracentric inversion who were of childbearing age had 19 children. No live-born children with birth defects were observed in either family. This evidence, together with the low frequency of miscarriages, suggests that crossover within the inversion loop occurs much less frequently than might be expected from the large size of this inversion. Our investigation suggests that the risk of recognized miscarriages, stilbirths, and live-born children with recombinant chromosomes who have birth defects may be much lower for inv(1) carriers than previously reported. The risk of having a malformed child because of a recombinant chromosome is probably less than 3% for carriers of the pericentric inversion and less than 6% for the carriers of the paracentric inversion.
Molecular detection of microscopic and submicroscopic deletions associated with Miller-Dieker syndrome.
Miller-Dieker syndrome (MDS), a disorder manifesting the severe brain malformation lissencephaly ("smooth brain"), is caused, in the majority of cases, by a chromosomal microdeletion of the distal short arm of chromosome 17. Using human chromosome 17-specific DNA probes, we have begun a molecular dissection of the critical region for MDS. To localize cloned DNA sequences to the MDS critical region, a human-rodent somatic cell hybrid panel was constructed which includes hybrids containing the abnormal chromosome 17 from three MDS patients with deletions of various sizes. Three genes (myosin heavy chain 2, tumor antigen p53, and RNA polymerase II) previously mapped to 17p were excluded from the MDS deletion region and therefore are unlikely to play a role in its pathogenesis. In contrast, three highly polymorphic anonymous probes, YNZ22.1 (D17S5), YNH37.3 (D17S28), and 144-D6 (D17S34), were deleted in each of four patients with visible deletions, including one with a ring chromosome 17 that is deleted for a portion of the single telomeric prometaphase subband p13.3. In two MDS patients with normal chromosomes, a combination of somatic cell hybrid, RFLP, and densitometric studies demonstrated deletion for YNZ22.1 and YNH37.3 in the paternally derived 17's of both patients, one of whom is also deleted for 144-D6. The results indicate that MDS can be caused by submicroscopic deletion and raises the possibility that all MDS patients will prove to have deletions at a molecular level. The two probes lie within a critical region of less than 3,000 kb and constitute potential starting points in the isolation of genes implicated in the severe brain maldevelopment in MDS.
Familial cavernous malformations of the central nervous system and retina.
We studied a family in which 4 persons from three generations had multiple cavernous malformations ("angiomas") of the central nervous system (CNS) and/or retina and found accounts in the literature of sixteen other families with this condition. In these families with familial cavernous malformation of the CNS and retina, 92% of pathologically documented vascular malformations were cavernous; 50% of those subjects affected had multiple CNS and/or retinal vascular malformations and 68% (excluding probands) were symptomatic. Cutaneous vascular lesions were an inconsistant manifestation. Autosomal dominant inheritance with high penetrance was confirmed.
Developmental aspects of lissencephaly and the lissencephaly syndromes.
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Familial Miller-Dieker syndrome associated with pericentric inversion of chromosome 17.
Recently it has been shown that most cases of the Miller-Dieker syndrome (MDS) are caused by deletion 17p13.3. All familial cases have been associated with a balanced reciprocal translocation in a carrier parent and unbalanced translocations in their affected offspring. We report a new case of familial MDS in whom the mother carries a pericentric inversion of chromosome 17. She has had two children with MDS, one of whom was shown to carry a recombinant 17 consisting of dup(17q) and del(17p). The high frequency of familial MDS and its consistent association with balanced chromosomal rearrangements in one of the parents makes it important to do high-resolution chromosome analysis on all patients with MDS and possibly all patients with lissencephaly. Finding a familial balanced rearrangement makes prenatal diagnosis of this condition feasible.
Neonatal adrenoleukodystrophy: new cases, biochemical studies, and differentiation from Zellweger and related peroxisomal polydystrophy syndromes.
Eight new cases of autopsy-confirmed or suspected neonatal adrenoleukodystrophy (NALD) are presented together with new biochemical data on very-long-chain fatty acids (VLCFA) and plasmalogens and a review of all previously published cases. The clinical, biochemical, and histopathologic abnormalities characteristic of this newly recognized form of adrenoleukodystrophy are analyzed in detail and compared to the principal characteristics of the similar disorder, the cerebrohepatorenal syndrome of Zellweger (ZS). Using strict pathologic criteria for the diagnosis of NALD, we find that, despite many clinical resemblances, NALD and the ZS are distinguishable on the basis of histology and peroxisomal biochemistry. Patients with NALD demonstrate adrenal atrophy, systemic infiltration by abnormal lipid-laden macrophages, and elevations of saturated VLCFA. In contrast, patients with ZS have chondrodysplasia, glomerulocystic disease of the kidney, central nervous system dysmyelination, and elevations of unsaturated as well as saturated VLCFA, but they lack adrenal atrophy. We conclude that NALD and the ZS probably represent at least two different genetic defects.
Interstitial deletion of (17)(p11.2p11.2): report of six additional patients with a new chromosome deletion syndrome.
Recently, a new clinically recognizable syndrome resulting from a small interstitial deletion of 17p [del(17)(p11.2p11.2)] was described in ten unrelated patients. We have identified six additional patients with similar cytogenetic and phenotypic abnormalities. Consistent clinical manifestations include 1) brachycephaly with a broad face and nasal bridge, 2) flat midface, 3) short, broad hands, and 4) mental retardation associated with hyperactivity and often self-destructive behavior. The craniofacial and hand anomalies are reminiscent of several craniosynostosis syndromes. Most patients also had growth deficiency and several other (more variable) congenital malformations. Chromosome studies with special attention to 17 should be performed in any patient with a similar phenotype.
Deficiency of chromosome 8p21.1----8pter: case report and review of the literature.
The clinical manifestations and cytogenetic changes of a patient with 46,XY,del(8)(p21.1) are compared with those of nine other patients with a similar deficiency of chromosome 8. Patients with this chromosome anomaly have a syndrome of postnatal growth retardation, microcephaly, mental retardation, epicanthal folds, posteriorly angulated and malformed ears, short neck, relatively increased internipple distance, and congenital heart defect. A short and broad nose, a wide and flat nasal bridge, and a small jaw are observed in young patients but tend to become less apparent with increasing age. In most instances, the syndrome has been associated with a de novo chromosome abnormality. Levels of glutathione reductase in our patient were normal-a finding consistent with localization of the gene coding for this enzyme to the proximal part of band 8p21.1 if gene dosage studies are reliable.
Syndromes with lissencephaly. II: Walker-Warburg and cerebro-oculo-muscular syndromes and a new syndrome with type II lissencephaly.
Lissencephaly (smooth brain) is an abnormality of brain development characterized by incomplete neuronal migration and a smooth cerebral surface. At least two distinct pathological types occur, each associated with several recognized syndromes. In this paper, we report on the clinical and pathologic manifestations of four additional patients and classify and delineate three separate disorders with type II lissencephaly. We also report on a previously undescribed abnormality in one of the four patients--dilated rough endoplasmic reticulum cisternae containing an unknown osmiophilic secretory product, probably a glycoprotein.
Further comments on the lissencephaly syndromes.
Detailed clinical, pathological, and cytogenetic investigations of patients with lissencephaly over the past several years have demonstrated the existence of at least eight distinct conditions with variable genetic implications. In several of these disorders, especially chromosomally normal MDS, ILS, and CCL, too few patients have been reported to permit citation of accurate recurrence risk figures. Accordingly, we wish to begin a registry of patients with lissencephaly of all types for the purpose of developing such risk figures and request that any available information be sent to one of us (W.B.D. or J.M.O.).
Syndromes with lissencephaly. I: Miller-Dieker and Norman-Roberts syndromes and isolated lissencephaly.
Lissencephaly (smooth-brain) is an abnormality of brain development characterized by incomplete neuronal migration and a smooth cerebral surface. At least 2, and possibly more, distinct pathological types occur, each associated with several distinct syndromes. In this paper, the manifestations of 3 disorders associated with type I (classical) lissencephaly are discussed, including the Miller-Dieker syndrome with or without deficiency of 17p13, Norman-Roberts syndrome, and isolated lissencephaly sequence.
New chromosomal syndrome: Miller-Dieker syndrome and monosomy 17p13.
The Miller-Dieker Syndrome (MDS) consists of lissencephaly, characteristic facies, pre- and postnatal growth retardation, plus various other birth defects. Autosomal recessive inheritance has been presumed based on four reported families with two or more affected siblings. We present substantial evidence that monosomy 17p13.3 causes the MDS phenotype. This includes two patients with ring chromosome 17, one patient with a de novo 17p13 deletion, and one patient with monosomy 17p due to an unbalanced 7p; 17p translocation. We report the first prenatal diagnosis of MDS in a 20-week fetus from this latter family. Additionally, we report a balanced translocation between chromosome 17 and different autosomes (8, 12, and 15) in three of the four familial cases of lissencephaly. The finding of a chromosomal basis for this presumed autosomal recessive disorder significantly alters genetic counseling and makes prenatal diagnosis possible in some families.
Miller-Dieker syndrome: lissencephaly and monosomy 17p.
Miller-Dieker syndrome, which includes lissencephaly and a characteristic phenotypic appearance, has been reported to have an autosomal recessive pattern of inheritance. However, we have found abnormalities of chromosome 17 in two of three unrelated patients with this syndrome, one with a ring chromosome 17 and the other with an unbalanced translocation resulting in partial monosomy of 17p13. A review of the literature revealed five additional patients in three families, who had Miller-Dieker syndrome and an abnormality of 17p. Thus, we propose that monosomy of distal 17p may be the cause of Miller-Dieker syndrome in some patients.