American Journal of Medical Genetics, Part A

In the hedgehog signaling network, mutations result in various phenotypes, including, among others, holoprosencephaly, nevoid basal cell carcinoma syndrome, Pallister‐Hall syndrome, Greig cephalopolysyndactyly, Rubinstein‐Taybi syndrome, isolated basal cell carcinoma, and medulloblastoma. Active Hedgehog ligand is double lipid modified with a C‐terminal cholesterol moiety and an N‐terminal palmitate. Transport active Hedgehog from the signaling cell to the responding cell occurs through three mechanisms: 1). formation of multimeric Hedgehog which makes it soluble; 2). function of Dispatched in releasing the lipid‐anchored protein from the signaling cell; and 3). movement across the plasma membrane of the responding cell by Tout‐velu‐dependent synthesis of heparan sulfate proteoglycan. In the responding cell, active Hedgehog binds to its receptor Patched, a 12‐pass transmembrane protein, which frees Smoothened, an adjacent 7‐pass transmembrane protein, for downstream signaling. Patched and Smoothened may shuttle oppositely between the plasma membrane and endocytic vesicles in response to active Hedgehog ligand. In downstream signaling, Cubitus interruptus (Gli proteins in vertebrates), Costal 2, Fused, and Suppressor of Fused form a tetrameric complex. Cubitus interruptus is a bifunctional transcription regulator. In the absence of active Hedgehog ligand, a truncated transcriptional repressor is generated that binds target genes and blocks their transcription. In the presence of active Hedgehog ligand, a full length transcriptional activator binds target genes and upregulates their transcription. Target genes include Wingless (Wnt gene family in vertebrates), Decapentaplegic (Bone Morphogenetic Proteins in vertebrates), and Patched. The upregulation of Patched expression, resulting in Patched protein at the cell membrane, sequesters Hedgehog and limits its spread beyond the cells in which it is produced. Thus, a balance is created by the antagonism of Hedgehog and Patched, whose relative concentrations alternate with respect to each other. Many more factors that are essential for the hedgehog signaling network are also discussed: Megalin, Rab23, Hip, GAS1, PKA, GSK3, CK1, Slimb, SAP18, and CBP. © 2003 Wiley‐Liss, Inc.

Mycophenolate mofetil (MMF) (CellCept®) is an immunosuppressant drug that is teratogenic in rats and rabbits. Reports of malformations in 13 offspring of women exposed to MMF in pregnancy raise concern that MMF is also a human teratogen. We report an additional child with malformations following prenatal exposure to MMF and review the other 13 reports. We identified a Cambodian male born at 31 weeks' gestation to a mother who had been treated for lupus nephritis with MMF from before conception to 12 weeks' gestational age. He had bilateral moderate‐to‐severe microtia, external auditory canal atresia, bilateral conductive hearing loss, mild microcephaly, and apparently normal development. Among the 14 MMF‐exposed offspring now reported, the underlying maternal conditions were kidney transplantation (7), lupus nephritis (4), liver transplantation (1), heart transplantation (1), and recurrent erythema multiforme (1). All were exposed in early pregnancy. The most distinctive malformation was moderate‐to‐severe microtia or anotia (12), with external auditory canal atresia in 9. Other common craniofacial malformations and minor anomalies included orofacial clefts (7), hypertelorism (3), coloboma (3), and micrognathia (3). Six had cardiovascular malformations, of which three were either conotruncal or aortic arch defects. MMF dose, reported in 12 patients, was <1 g/day in 4 and 1 g or more/day in 8; no correlation between dose and phenotype severity was apparent. While case reports have limited value in identifying human teratogens, the unusual distribution of malformations among the 14 reported exposed offspring identifies a phenotype suggesting that MMF is likely a human teratogen. © 2009 Wiley‐Liss, Inc.

After maternal exposure to mycophenolate in pregnancy a high number of fetal losses and a specific pattern of birth defects consisting of microtia, cleft lip, and other anomalies have been reported. However, so far, prospective data on pregnancy outcome allowing quantitative risk assessment are missing. We report on 57 prospectively ascertained pregnancies after maternal therapy with mycophenolate (mycophenolate mofetil or mycophenolate sodium) identified by European Teratology Information Services (ETIS) through their risk consultation process. The outcome of these prospective pregnancies was as follows: 16 spontaneous abortions, 12 elective terminations of pregnancy (ETOP) (including two late terminations for multiple malformations consistent with mycophenolate embryopathy), and 29 liveborn infants. The probability of spontaneous abortion was about 45% (95% CI 29 to 66%) estimated using survival analysis technique. Six out of 29 live born infants had major congenital defects: Two with external auditory canal atresia (EACA) (with and without microtia), one with tracheo‐esophageal atresia, one with severe hydronephrosis, one with an atrial septal defect (ASD) and one with a myelomeningocele. Thus, at least four fetuses/infants of our prospective case series had a clinical phenotype consistent with mycophenolate embryopathy. Our results confirm a high incidence of major malformations (26%) after first trimester exposure to mycophenolate. Apart from exposure to mycophenololate, the underlying maternal disease and concomitant medication may also have contributed to the other poor pregnancy outcomes such as a high rate of spontaneous abortions, prematurity (62%), and low birth weight (31%). © 2012 Wiley Periodicals, Inc.

Previous studies on the incidence of the various types of mucopolysaccharidoses (MPS) in different populations have shown considerable variation. However, information regarding the incidence of MPS in the Asian population is lacking. An epidemiological study of the MPS disorders in Taiwan using multiple ascertainment sources was undertaken, and incidences of different types of MPS during the period of 1984–2004 were estimated. We compared our data with previous reports in different populations. The combined birth incidence for all MPS cases was 2.04 per 100,000 live births. MPS II (Hunter syndrome) had the highest calculated birth incidence of 1.07 per 100,000 live births (2.05 per 100,000 male live births), comprising 52% of all MPS cases diagnosed. The birth incidences of MPS I (Hurler syndrome), III (Sanfilippo syndrome), IV (Morquio syndrome), and VI (Maroteaux‐Lamy syndrome) were 0.11, 0.39, 0.33, and 0.14 per 100,000 live births, respectively, which accounted for 6%, 19%, 16%, and 7% of all MPS, respectively. No cases of MPS III D (Sanfilippo syndrome type D), MPS IV B (Morquio syndrome type B), MPS VII (Sly syndrome) or MPS IX were ascertained during the study period. Overall incidence of MPS in Taiwan was consistent with that reported in Western populations. However, in contrast to the higher incidence of MPS I in most Western populations, this study showed a higher incidence of MPS II in Taiwan. It remains to be investigated whether this discrepancy is attributed to the under‐diagnosis of MPS I in Taiwan or to ethnic differences. © 2009 Wiley‐Liss, Inc.

Sanfilippo syndrome, or mucopolysaccharidosis type III (MPSIII) is a lysosomal storage disease with predominant neurological manifestations in affected children. It is considered heterogeneous with respect to prevalence, clinical presentation, biochemistry (four biochemical forms of the disease referred to as MPSIIIA, B, C, and D are known), and causative mutations. The perspective of therapeutic options emphasizes the need for better knowledge of MPSIII incidence and natural history. We performed parallel retrospective epidemiological studies of patients diagnosed with MSPIII in France (n = 128), UK (n = 126), and Greece (n = 20) from 1990 to 2006. Incidences ranged from 0.68 per 100,000 live‐births in France to 1.21 per 100,000 live‐births in UK. MPSIIIA, which predominates in France and UK, was absent in Greece, where most patients have MPSIIIB. The study confirmed the large allelic heterogeneity of MPSIIIA and MPSIIIB and detected several yet undescribed mutations. Analysis of clinical manifestations at diagnosis and over a 6–7 years follow‐up indicated that almost all patients, whatever the disease subtype, expressed neurological manifestations before the age of 5 years, including language acquisition delay, cognitive delay, and/or abnormal behavior. In contrast to relatively homogeneous early onset manifestations, disease progression showed significant variation depending on subtype and age at diagnosis. Different severities of disease progressions and different allele distribution between France and UK suggested that mutations are not equally deleterious, although genotype–phenotype correlation could not be established. Notwithstanding the rapidity of further clinical deterioration, all MPSIII patients suffer early onset devastating neurological manifestations that deserve early treatment when available. © 2010 Wiley‐Liss, Inc.

To report on the cognitive and behavioral attributes of 61 children with Down syndrome (DS) and autistic‐spectrum disorder (ASD) according to DSM‐IV criteria; to determine the utility of the aberrant behavior checklist (ABC) to characterize these subjects for research purposes; and to test the hypothesis that subjects with DS + ASD could be distinguished from their typical DS peers using the ABC. Cross‐sectional design. Cases with DS + ASD (N = 61), comparison group of DS + stereotypy movement disorder (SMD) (N = 26) and typical DS controls without behavior problems (N = 44) were ascertained and enrolled sequentially upon presentation to a DS clinic at an academic medical center over a 10‐year period from 1991 to 2001. All subjects underwent neurodevelopmental and medical evaluation, and standardized cognitive testing. The parents provided responses to standardized behavioral questionnaires. Cognitive function (IQ) differed markedly across the three groups. The Lethary and Stereotypy subscales of the ABC were highly significant (P < 0.001) in distinguishing the three groups from one another. Within the ASD group differences were apparent by DSM‐IV type on the Lethargy subscale, which reached significance, ANOVA (F = 0.002) andt‐test (Autism > PDD,P = 0.005; PDD < CDD,P = 0.002). Using a multivariate regression model, the ABC scales alone explained 62% of variance of ASD outcome; addition of demographic variables explained up to 68% of the variance. There is good correlation between DSM‐IV criteria for autism and subscales scores on the ABC in subjects with DS. This study demonstrates the feasibility of using the ABC to characterize the neurobehavioral phenotype of a cohort of children with trisomy 21 and ASD for ongoing research purposes. © 2005 Wiley‐Liss, Inc.

Amelogenesis imperfecta hypoplastic‐hypomaturation with taurodontism (AIHHT) is an autosomal dominant (AD) trait associated with enamel defects and enlarged pulp chambers. In this study, we mapped an AIHHT family to human chromosome 17 q21‐q22 (lod score 3.3) and identify a two basepair deletion (CT) at nucleotide 560 in DLX3 associated with the disease. This mutation causes a frameshift altering the last two amino acids of the DNA‐binding homeodomain introducing a premature stop codon truncating the protein by 88 amino acids. This is the first report of a mutation within the homeodomain of DLX3. Previous studies have shown a DLX3 mutation outside the homeodomain associated with tricho‐dento‐osseous syndrome (TDO) suggesting TDO and some forms of AIHHT are allelic. copy; 2005 Wiley‐Liss, Inc.