American Journal of Medical Genetics最新文献

The TM4SF2 gene (localized at Xp11.4 between the loci DXS564 and DXS556) has been found to be mutated in one MRX family. In order to define the corresponding behavioral phenotype, global IQ and specific cognitive skills were assessed in seven males and three females of this family, independent of subject status. Mental retardation (MR) was mild in three patients and moderate in three others. Despite the broad variability of severity of MR, a cognitive profile specific to the MR in this family was documented. It was characterized by language disorder that was more marked in the articulatory component and spatial/verbal short-term memory dissociation with larger mnemonic span for spatial than for verbal cues. Linkage analysis was then performed on the basis of the cognitively determined status. Recombinations were observed with the loci DXS556 at Xp11.4 and DXS441 at Xq13.2 (maximum LOD score = 2.23 at theta = 0 for ALAS2). This localization region does not include the TM4SF2 gene that has been found mutated in both patients with MR and in one non-MR male subject of this family. The present results suggest two main hypotheses. First, TM4SF2 gene mutation could be involved in MR in this family, therefore representing accentuated intra familial phenotypic variability. Second, the structural particularity detected in the TM4SF2 gene might reflect a rare polymorphism rather than a pathogenic mutation, with the gene responsible for MR in this family being therefore more likely to be searched for in the pericentromeric region of the X chromosome.

Kousseff syndrome was originally described by Boris Kousseff in 1984: Pediatrics 74:395-398 in three siblings whose main features were conotruncal heart defects, neural tube defects, and dysmorphic features. The proband is a white male who has spina bifida, shunted hydrocephalus, cleft palate, short stature, cognitive impairment, and the typical craniofacial features of velo-cardio-facial syndrome (VCFS), including low-set and dysplastic ears, broad base of the nose, narrow alae nasi, and retrognathia. The family history is significant for a brother who died at 2 weeks of age with myelomeningocele, hydrocephalus, transposition of the great vessels, and unilateral renal agenesis, and a sister who died at 11 days of age with myelomeningocele, truncus arteriosus, hypocalcemia, and autopsy findings of absent thymus and parathyroid glands, consistent with DiGeorge anomaly. Given the clinical findings, family history, and recent knowledge that open neural tube defects can occur in VCFS/DiGeorge anomaly, FISH analysis for 22q11-13 deletion was performed on the proband. A deletion was detected in him and subsequently confirmed in his father. Molecular analysis on autopsy material confirmed the deletion in the proband's deceased brother. We suggest that individuals with neural tube defects associated with other anomalies such as congenital heart defects or cleft palate be evaluated for 22q deletions.

Two families, originally diagnosed as having nonsyndromic X-linked mental retardation (NSXLMR), were reviewed when it was shown that they had a 24-bp duplication (428-45 1dup(24bp)) in the ARX gene [Stromme et al., 2002: Nat Genet 30:441-445]. This same duplication had also been found in three other families: one with X-linked infantile spasms and hypsarrhythmia (X-linked West syndrome, MIM 308350) and two with XLMR and dystonic movements of the hands (Partington syndrome, MIM 309510). On review, manifestations of both West and Partington syndromes were found in some individuals from both families. In addition, it was found that one individual had autism and two had autistic behavior, one of whom had epilepsy. The degree of mental retardation ranged from mild to severe. A GCG trinucleotide expansion (GCG)10+7 and a deletion of 1,517 bp in the ARX gene have also been found in association with the West syndrome, and a missense mutation (1058C>T) in a family with a newly recognized form of myoclonic epilepsy, severe mental retardation, and spastic paraplegia [Scheffer et al., 2002: Neurology, in press]. Evidently all these disorders are expressions of mutations in the same gene. It remains to be seen what proportions of patients with infantile spasms, focal dystonia, autism, epilepsy, and nonsyndromic mental retardation are accounted for by mutations in the ARX gene.

Holoprosencephaly (HPE) is a condition characterized by a defect in the development of the midline embryonic forebrain. When detected prenatally, the diagnosis of HPE offers parents a poor but often uncertain prognosis. Since the majority of parents receiving a prenatal diagnosis of an abnormality terminate their pregnancies, few studies have examined parents' experiences and needs surrounding the decision to continue a pregnancy. We present a descriptive study of in-depth interviews with 24 parents who chose to continue their pregnancy after receiving a prenatal diagnosis of HPE. Parents were asked about their decision-making process to continue the pregnancy. Qualitative analysis was used to identify common themes that emerged from these parents' experiences. The results suggest that most parents did not make an active decision about continuing the pregnancy. Rather, they described a more subtle decision-making process that evolved over time and consisted of several factors. These factors included the parents' religious and personal beliefs, past experiences, and the uncertainty involved in the diagnosis of HPE. Throughout the decision-making process, they described informational, emotional, and supportive needs from family, friends, and health professionals. All of these factors contributed to the evolution of the parents' decision to continue the pregnancy and the acceptance of their decision. Results of this exploratory study suggest health care professionals need to work with parents as they make their decision to continue an affected pregnancy. The results also provide the groundwork for prospective investigation into parents' decision-making process as they receive and adjust to prenatal diagnoses of an abnormality.

We report a 2-year-5-month-old girl with malformed lower limbs. The radiographic skeletal survey revealed agenesis of the ilio-pubic rami with pubic dehiscence, right hip dislocation, bilateral coxa vara, short femurs, femoro-tibial synchondrosis, bilateral hypoplastic tibiae more severe on the left side, and hypoplastic left calcaneus and talus. To the best of our knowledge, this combination of multiple congenital skeletal abnormalities has not been reported before.

A 20-year-old female with trisomy 18 is described. Survival past infancy is rare in this disorder. Little is known concerning the factors that contribute to prolonged survival with this syndrome. This case provides an opportunity to review the management of older children and young adults with trisomy 18.

The purpose of this study was to evaluate chromosomal regions previously linked to pathological myopia for linkage to juvenile myopia in a sample of myopic children and their families. Of 125 families with a myopic child participating in the Orinda longitudinal study of myopia, 53 submitted 221 buccal swab samples for genetic analysis. Myopia in proband children was defined as -0.75 D or more myopia in both meridians on cycloplegic autorefraction (1% tropicamide). Affected status in parents and siblings was obtained by survey. DNA was extracted from buccal mucosal cells, amplified by polymerase chain reaction (PCR), and then analyzed with seven markers for chromosome 12 and five markers for chromosome 18 in the regions previously associated with pathological myopia. LOD scores were not significant for any marker tested. The largest positive LOD score was 0.15 for GATA30F04. Model-free methods using a SimIBD approach suggested a possible linkage at one marker, GATA6H09 (P = 0.003), but these results were not supported by transmission disequilibrium test (TDT) analysis. The statistical power to detect LOD scores of > or =1.0, assuming homogeneity, was estimated at 93.2%. We found no confirmatory evidence of linkage between juvenile myopia and regions of chromosomes 12 and 18 previously associated with pathological myopia.

In 1997, Narchi and Kulaylat, studying the incidence of Down syndrome in infants of gestational diabetic mothers, concluded that maternal diabetes increases the risk for Down syndrome, but failed to control the maternal age in their analysis. Using data from the Spanish Collaborative Study of Congenital Malformations (ECEMC), we analyzed the relationship between Down syndrome and maternal diabetes mellitus, and maternal gestational diabetes, controlling the maternal age through the pair-matching analysis, stratifying by maternal age and logistic regression analysis. The analyses show that maternal age is related either to Down syndrome as well as to both types of maternal diabetes. Thus, the overall analysis could be confounded by maternal age. Once we controlled the maternal age, the risk of maternal diabetes mellitus for Down syndrome is: odds ratio (OR) = 0.92 (0.41-2.07); P = 0.83. Controlling maternal age in gestational diabetes, the risk is OR = 1.18 (0.61-2.35); P > 0.70. Based on our results, we conclude that Down syndrome is related to maternal age, but does not seem to be related to any type of maternal diabetes.