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Biomedical subjects

L M Bird

Publications and source records attributed to L M Bird.

At least 19 recordsLinked to original sources
PubMed2006

Natural history of prenatally diagnosed 46,X,isodicentric Y.

OBJECTIVES: The karyotype 46,X,isodicentric Y has rarely been reported in the context of prenatal diagnosis. The literature is replete with descriptions of individuals with 46,X,isodicentric Y/45,X mosaicism, presenting with a spectrum of phenotypes. The postnatal phenotype is believed to depend on the extent of mosaicism in the gonads or other affected tissues. The purpose of this article is to delineate the natural history of this chromosomal abnormality when identified in the context of prenatal diagnosis. METHODS: We identified a 45,X/46,X,idicY karyotype in the structurally normal male fetus of a woman presenting with an abnormal triple screen. Four other prenatally ascertained cases were found in our files as well as ten in the medical literature. RESULTS: Of the 15 cases presented here, 11 (73%) were reported as phenotypically normal males, 1 was found to have an epididymal cyst, and 1 had normal male genitalia, but was also found to have a cardiovascular defect. One out of 15 (7%) was found to have female genitalia and was therefore confirmed to have Turner syndrome. In one case, the outcome was not reported. CONCLUSION: An individual diagnosed prenatally with idic(Y) may in many cases be a normal male, similar to the outcome for prenatally diagnosed 45,X/46,XY.

Chromosomes, Human, X↗
PubMed2005

Microarray based comparative genomic hybridization testing in deletion bearing patients with Angelman syndrome: genotype-phenotype correlations.

BACKGROUND: Angelman syndrome (AS) is a neurodevelopmental disorder characterised by severe mental retardation, dysmorphic features, ataxia, seizures, and typical behavioural characteristics, including a happy sociable disposition. AS is caused by maternal deficiency of UBE3A (E6 associated protein ubiquitin protein ligase 3A gene), located in an imprinted region on chromosome 15q11-q13. Although there are four different molecular types of AS, deletions of the 15q11-q13 region account for approximately 70% of the AS patients. These deletions are usually detected by fluorescence in situ hybridisation studies. The deletions can also be subclassified based on their size into class I and class II, with the former being larger and encompassing the latter. METHODS: We studied 22 patients with AS due to microdeletions using a microarray based comparative genomic hybridisation (array CGH) assay to define the deletions and analysed their phenotypic severity, especially expression of the autism phenotype, in order to establish clinical correlations. RESULTS: Overall, children with larger, class I deletions were significantly more likely to meet criteria for autism, had lower cognitive scores, and lower expressive language scores compared with children with smaller, class II deletions. Children with class I deletions also required more medications to control their seizures than did those in the class II group. CONCLUSIONS: There are four known genes (NIPA1, NIPA2, CYFIP1, & GCP5) that are affected by class I but not class II deletions, thus raising the possibility of a role for these genes in autism as well as the development of expressive language skills.

Angelman Syndrome↗
PubMed2005

Oculocerebrocutaneous syndrome: the brain malformation defines a core phenotype.

BACKGROUND: Oculocerebrocutaneous syndrome (OCCS) is characterised by orbital cysts and anophthalmia or microphthalmia, focal aplastic or hypoplastic skin defects, skin appendages, and brain malformations. The eye and skin abnormalities are well described but the neuropathological features less so. To date, 28 patients with an unequivocal diagnosis of OCCS have been reported, with a preponderance of males. OBJECTIVE: To evaluate the brain imaging studies, clinical records, photographs, and pathological material of two new and nine previously reported cases of OCCS. RESULTS: There was a consistent pattern of malformations in eight of the 11 cases, consisting of frontal predominant polymicrogyria and periventricular nodular heterotopia, enlarged lateral ventricles or hydrocephalus, agenesis of the corpus callosum sometimes associated with interhemispheric cysts, and a novel mid-hindbrain malformation. The latter consisted of a giant and dysplastic tectum, absent cerebellar vermis, small cerebellar hemispheres in most cases, and a large posterior fossa fluid collection. CONCLUSIONS: The mid-hindbrain malformation appears pathognomonic for OCCS. The eye and skin features of OCCS show considerable overlap with several other syndromes, such as encephalocraniocutaneous lipomatosis, oculo-auriculo-vertebral spectrum, and focal dermal hypoplasia, none of which has a comparable pattern of brain malformations. In particular the unique mid-hindbrain malformation also distinguishes OCCS from related syndromes with comparable forebrain anomalies. The pattern of malformation described thus helps in differentiating OCCS from other entities. The mid-hindbrain malformation points to a defect of the mid-hindbrain organiser as the underlying pathogenic mechanism.

Abnormalities, Multiple↗
PubMed2002

Choroid plexus cysts in the mid-trimester fetus--practical application suggests superiority of an individualized risk method of counseling for trisomy 18.

OBJECTIVES: Analysis of a referral population of patients with choroid plexus cysts (CPCs) was performed to compare an average risk method of counseling to an individualized risk method. METHODS: A total of 395 patients referred to a Prenatal Diagnosis Center were included, of whom 341 had isolated CPCs and 54 had associated ultrasound abnormalities. For isolated CPCs, an average risk of 1/150 for aneuploidy was compared to an individualized risk assessment [prior risk as determined by maternal age or serum screening multiplied by the likelihood ratio established by Gupta et al. (1997)]. Accuracy, cost, and procedure-related losses were assessed. RESULTS: Both methods resulted in 100% sensitivity. The individualized method resulted in greater specificity, decreased costs, and (theoretically) fewer procedure-related pregnancy losses. CONCLUSIONS: An individualized risk method of counseling utilizing the likelihood ratios established by Gupta et al. (1997) was superior to an average risk method for assessing trisomy 18 risk in the setting of CPC detected in mid-trimester.

Adult↗
PubMed2001

Scanning for telomeric deletions and duplications and uniparental disomy using genetic markers in 120 children with malformations.

We screened 120 children with sporadic multiple congenital anomalies and either growth or mental retardation for uniparental disomy (UPD) or subtelomeric deletions. The screening used short tandem repeat polymorphisms (STRP) from the subtelomeric regions of 41 chromosome arms. Uninformative marker results were reanalyzed by using the next available marker on that chromosome arm. In total, approximately 25,000 genotypes were generated and analyzed for this study. Subtelomeric deletions of 1 Mb in size were excluded for 27 of 40 chromosome arms. Among the 120 subjects none was found to have UPD, but five subjects (4%, 95% confidence interval 1-9%) were found to have a deletion or duplication of one or more chromosome arms. We conclude that UPD is not a frequent cause of undiagnosed multiple congenital anomaly syndrome. In addition, we determined that 9p and 7q harbor chromosome length variations in the normal population. We conclude that subtelomeric marker analysis is effective for the detection of subtelomeric duplications and deletions, although it is labor intensive. Given a detection rate that is similar to prior studies and the large workload imposed by STRPs, we conclude that STRPs are an effective, but impractical, approach to the determination of segmental aneusomy given current technology.

Abnormalities, Multiple↗
PubMed2001

Humoral immunodeficiency with facial dysmorphology and limb anomalies: a new syndrome.

We report a 6 year old girl with an isolated humoral immune deficiency and a unique combination of dysmorphic features. Physical findings include microcephaly, micrognathia, sickle shaped eyebrows, hypoplastic alae nasi, thenar hypoplasia, partial 4-5 syndactyly of toes, recessed great toes, anterior anus, and hypoplastic labia minora. Radiographic findings include triphalangeal thumbs and hypoplastic first metatarsals. She has postnatal growth retardation and her development is substantially slower than her twin's. Her clinical course has been complicated by recurrent sinopulmonary infections and pneumococcal bacteraemia. Laboratory evaluation revealed hypogammaglobulinaemia, absent B cells, and a 46,XX karyotype. A review of the literature and the London Dysmorphology Database did not produce any recognizable syndromes that match her constellation of findings. She may represent a unique syndrome of unknown etiology.

Abnormalities, Multiple↗
PubMed2000

Cortical dysgenesis in 2 patients with chromosome 22q11 deletion.

Two patients with chromosome 22q11 deletion and cortical dysgenesis (gyral abnormalities) are reported in this study. One had unilateral clubfoot in addition to multiple features suggestive of the Di George syndrome (DGS), and the other presented with leg asymmetry and seizures, with subsequent recognition of the velo-cardio-facial syndrome (VCFS). In each patient, gyral abnormalities were identified in the hemisphere contralateral to the limb abnormality. A wide range of central nervous system abnormalities have been reported in DGS and VCFS, including three prior reports of gyral abnormalities (lissencephaly, microgyria). The 2 patients reported herein strengthen the association between the 22q11 deletion spectrum and cortical dysgenesis, but the underlying pathogenetic mechanism (primary neural migration vs. vascular disruption) remains unclear.

Adult↗
PubMed1997

X-linked situs abnormalities result from mutations in ZIC3.

Vertebrates position unpaired organs of the chest and abdomen asymmetrically along the left-right (LR) body axis. Each structure comes to lie non-randomly with respect to the midline in an overall position designated situs solitus, exemplified in humans by placement of the heart, stomach and spleen consistently to the left. Aberrant LR axis development can lead to randomization of individual organ position (situs ambiguus) or to mirror-image reversal of all lateralized structures (situs inversus). Previously we mapped a locus for situs abnormalities in humans, HTX1, to Xq26.2 by linkage analysis in a single family (LR1) and by detection of a deletion in an unrelated situs ambiguus male (Family LR2; refs 2,3). From this chromosomal region we have positionally cloned ZIC3, a gene encoding a putative zinc-finger transcription factor. One frameshift, two missense and two nonsense mutations have been identified in familial and sporadic situs ambiguus. The frameshift allele is also associated with situs inversus among some heterozygous females, suggesting that ZIC3 functions in the earliest stages of LR-axis formation. ZIC3, which has not been previously implicated in vertebrate LR-axis development, is the first gene unequivocally associated with human situs abnormalities.

Amino Acid Sequence↗
PubMed1997

Anencephaly with holoprosencephalic facies due to ring chromosome 18.

An anencephalic infant with holoprosencephalic facies and ring chromosome 18 [r(18)] is reported with review of the pertinent literature. Although the association of anencephaly and holoprosencephalic facies is well established, this is the first instance of an accompanying karyotypic abnormality. Review of other r(18) cases suggests that this is not a coincidental finding. Karyotype analysis appears warranted in cases of anencephaly with holoprosencephalic facies.

Anencephaly↗
PubMed1996

Sudden death in Williams syndrome: report of ten cases.

Williams syndrome (WS) is a recognizable pattern of malformation with mental retardation, mild growth deficiency, characteristic facies and temperament, and cardiovascular disease. Sudden death is a recognized complication of WS; however, it is thought to be rare. The clinical features of 10 children with WS who died suddenly are reported here, doubling the number of unexpected deaths reported in the literature. We suggest that sudden death is a more common complication than has been assumed previously. Pathologic findings on the seven autopsy cases implicate two anatomic abnormalities that predispose individuals with WS to sudden death: coronary artery stenosis and severe biventricular outflow tract obstruction. The mechanisms for sudden death for both anatomic subgroups include myocardial ischemia, decreased cardiac output, and arrhythmia. We believe these observations warrant the development of strategies for monitoring patients with WS in an attempt to identify those at increased risk of sudden death.

Aortic Valve↗
PubMed1996

Heritability of X chromosome--inactivation phenotype in a large family.

One of the two X chromosomes in each somatic cell of normal human females becomes inactivated very early in embryonic development. Although the inactivation of an X chromosome in any particular somatic cell of the embryonic lineage is thought to be a stochastic and epigenetic event, a strong genetic influence on this process has been described in the mouse. We have attempted to uncover evidence for genetic control of X-chromosome inactivation in the human by examining X chromosome-inactivation patterns in 255 females from 36 three-generation pedigrees, to determine whether this quantitative character exhibits evidence of heritability. We have found one family in which all seven daughters of one male and the mother of this male have highly skewed patterns of X-chromosome inactivation, suggesting strongly that this quantitative character is controlled by one or more X-linked genes in some families.

Alleles↗
PubMed1995

Transmission-ratio distortion of X chromosomes among male offspring of females with skewed X-inactivation.

We have begun a search for heritable variation in X-chromosome inactivation pattern in normal females to determine whether there is a genetic effect on the imprinting of X-chromosome inactivation in humans. We have performed a quantitative analysis of X-chromosome inactivation in lymphocytes from mothers in normal, three-generation families. Eight mothers and 12 grandmothers exhibited evidence of highly skewed patterns of X-chromosome inactivation. We observed that the male offspring of females with skewed X-inactivation patterns were three times more likely to inherit alleles at loci that were located on the inactive X chromosome (Xi) than the active X chromosome (Xa). The region of the X chromosome for which this phenomenon was observed extends from Xp11 to -Xq22. We have also examined X-chromosome inactivation patterns in 21 unaffected mothers of male bilateral sporadic retinoblastoma patients. Six of these mothers had skewed patterns of X-chromosome inactivation. In contrast to the tendency for male offspring of skewed mothers from nondisease families to inherit alleles from the inactive X chromosome, five of the six affected males inherited the androgen receptor alleles from the active X chromosome of their mother.

Base Sequence↗
PubMed1994

Female infant with oncocytic cardiomyopathy and microphthalmia with linear skin defects (MLS): a clue to the pathogenesis of oncocytic cardiomyopathy?

A infant girl had red stellate skin lesions on the cheeks and neck, and mildly short palpebral fissures. Her skin abnormality was typical of microphthalmia with linear skin defects (MLS), a newly recognized syndrome consisting of congenital linear skin defects and ocular abnormalities in females monosomic for Xp22. She died suddenly and unexpectedly at age 4 months; the cause of death was ascribed to oncocytic cardiomyopathy. Oncocytic cardiomyopathy occurs only in young children, who present with refractory arrhythmias leading to cardiac arrest. The coexistence of two rare conditions, one of which is mapped to the X chromosome, and an excess of affected females with oncocytic cardiomyopathy, make it likely that oncocytic cardiomyopathy is also X-linked, with Xp22 being a candidate region. Overlapping manifestations in the two conditions (ocular abnormalities in cases of oncocytic cardiomyopathy and arrhythmias in MLS) offer additional support for this hypothesis.

Abnormalities, Multiple↗
PubMed1994

Recurrence of diaphragmatic agenesis associated with multiple midline defects: evidence for an autosomal gene regulating the midline.

We report the familial occurrence of diaphragmatic agenesis in association with other midline anomalies in a brother and sister. Opitz and Gilbert [Am J Med Genet 1982, 12:443-455] introduced the concept of the midline as a developmental field, and there have been reports of pedigrees compatible with the hypothesis of an X-linked gene regulating the development of the midline. This family suggests that an autosomal gene also contributes to the morphogenesis of midline structures.

Abnormalities, Multiple↗