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Biomedical subjects

B M Finucane

Publications and source records attributed to B M Finucane.

9 recordsLinked to original sources

In vivo brain myo-inositol levels in children with Down syndrome.

The Na+/myo-inositol cotransporter (SLC5A3) gene, located on the long arm of human chromosome 21, may play a key role in osmoregulation including the regulation of levels of the "idiogenic osmole," myo-inositol, in brain cells. To determine whether the levels of myo-inositol are increased in the basal ganglia of children with Down syndrome, we performed in vivo brain hydrogen 1-nuclear magnetic resonance or 1H-magnetic resonance spectroscopy and measured plasma osmolality in a cohort of children with trisomy 21. Myo-inositol is elevated in the corpus striatum of infants and children with Down syndrome, even in the absence of hypertonic stress.

Adolescent↗

Facial emotion identification in males with fragile X syndrome.

Fifteen postpubertal males with fragile X syndrome (FRA(X)) and 15 non-FRA(X) males matched on IQ and age were assessed for their ability to identify the facially expressed emotions of happiness, sadness, anger, fear, disgust, and surprise. Emotions of happiness and sadness were the easiest to identify for both groups of participants. Regardless of etiology, individuals with higher IQ scores performed better at this task than did individuals with lower IQ scores. Results were consistent with findings in females having the fragile X mutation. The current study supported the notion that FRA(X) individuals are sensitive to facial emotion cues presented by others. This finding is discussed in the context of autism and gaze aversion.

Adolescent↗

Haploinsufficiency of cytosolic serine hydroxymethyltransferase in the Smith-Magenis syndrome.

Folate-dependent one-carbon metabolism is critical for the synthesis of numerous cellular constituents required for cell growth, and serine hydroxymethyltransferase (SHMT) is central to this process. Our studies reveal that the gene for cytosolic SHMT (cSHMT) maps to the critical interval for Smith-Magenis syndrome (SMS) on chromosome 17p11.2. The basic organization of the cSHMT locus on chromosome 17 was determined and was found to be deleted in all 26 SMS patients examined by PCR, FISH, and/or Southern analysis. Furthermore, with respect to haploinsufficiency, cSHMT enzyme activity in patient lymphoblasts was determined to be approximately 50% that of unaffected parent lymphoblasts. Serine, glycine, and folate levels were also assessed in three SMS patients and were found to be within normal ranges. The possible effects of cSHMT hemizygosity on the SMS phenotype are discussed.

Abnormalities, Multiple↗

The spasmodic upper-body squeeze: a characteristic behavior in Smith-Magenis syndrome.

The authors have observed a hand- and arm-squeezing behavior that seems to be highly characteristic of Smith-Magenis syndrome (SMS). This behavior serves as a useful diagnostic marker for SMS, a disorder in which the physical phenotype is often subtle. The squeezing behavior appears to be part of a complex upper-body tic which is exacerbated by happiness, excitement or overstimulation. The tic most often manifests as a 'self-hug', and is frequently associated with facial grimacing. Fleeting arm- and hand-squeezing movements may be repeated hundreds of times over the course of a day, but they do not significantly interfere with other hand functions. The excitable self-hugging in people with SMS may be one of the more benign and appealing aspects of their behavioral phenotype.

Adolescent↗

Eye abnormalities in the Smith-Magenis contiguous gene deletion syndrome.

We present the results of ophthalmologic assessment in 10 patients with interstitial chromosome deletions of 17p11.2, otherwise known as the Smith-Magenis syndrome (SMS). The most common abnormalities noted were strabismus, Brushfield spots, high myopia, and retinal detachments. We have previously reported high myopia and retinal detachments in 6 patients with SMS (Finucane et al.: Am J Hum Genet 49:262A, 1991). We present additional details on these individuals, as well as findings in 4 newly reported patients. Ocular pathology appears to be very common in SMS, significantly contributing to disability in people with this syndrome. The combination of high myopia, self-injurious head-banging, aggression, and hyperactivity among these patients makes them particularly susceptible to retinal detachments. Detailed ophthalmologic assessment should be included in the clinical work-up and monitoring of all patients with SMS resulting from deletion 17p11.2.

Adolescent↗

Mosaicism for deletion 17p11.2 in a boy with the Smith-Magenis syndrome.

We describe a 14-year-old boy with physical and behavioral manifestations of the Smith-Magenis syndrome. Low level mosaicism (11%) for deletion 17p11.2 was found in peripheral blood lymphocytes. The deletion was also observed in 100% of metaphases examined from skin fibroblast cultures. We confirm that the Smith-Magenis syndrome is associated with a highly recognizable phenotype. Because evidence of the abnormal cell line may be minimal or absent in peripheral blood, fibroblast studies are indicated for patients in whom mosaicism for deletion 17p11.2 is suspected clinically.

Adolescent↗

Study of color vision in fragile X syndrome.

Various theories have been postulated to account for the unusual inheritance pattern observed in the fragile X syndrome. The recent finding of a secondary amplification of the fragile X mutation in the offspring of carrier females [Oberle et al., 1991; Yu et al., 1991] is consistent with a maternal imprinting process. Laird [1987] has proposed that the fragile X mutation blocks complete reactivation of a previously inactivated fragile X chromosome. We have tested whether or not such a localized block extends as far distal as the red/green color-vision complex at Xq28. We found no evidence of color-vision defects among 25 male subjects with the fragile X syndrome. A fragile X positive woman also had normal color vision, despite being an obligate carrier of her father's gene for red/green color blindness. We conclude that the fragile X gene does not affect the function of neighboring color-vision genes, nor does it affect their ability to compensate adequately for inherited color deficiency on the homologous X chromosome in females.

Adolescent↗