Frequency of the thermolabile variant C677T in the MTHFR gene and lack of association with neural tube defects in the State of Yucatan, Mexico.

The C677T variant in the MTHFR gene is considered to be an associated risk factor for neural tube defects. However, the association has not been found in some ethnic groups. In order to assess the association between neural tube defects and the C677T variant, we determined the frequency of this variant in the MTHFR gene in the State of Yucatan, Mexico, where neural tube defects are highly prevalent. The study was performed on 65 subjects with spine bifida, 60 of their mothers and 110 control subjects. The presence of the C677T variant was determined by amplification and digestion with HinF1 of each subject's DNA. Genotypic and allelic frequencies were calculated for all groups. We did not observe any statistically significant difference in the genotypic or allelic frequencies between cases and controls for any of the groups studied (p > 0.05), suggesting that the thermolabile variant C677T is not an associated risk factor neither for the development of neural tube defects nor for mothers to have affected offspring in the population from Yucatan. Interestingly, the frequency of the C677T variant (54%) obtained in the Yucatan population is one of the highest reported (p < 0.01) and confirmed the high frequency of this allele throughout Mexico.

Full mosaic monosomy 22 in a child with DiGeorge syndrome facial appearance.

We describe an abnormal premature male infant with mosaic monosomy of chromosome 22. He had a unique facial appearance, similar to those with DiGeorge syndrome, and hypertonicity, limitation of extension at major joints, and flexion contractures of all fingers. This rare chromosomal aberration has been reported previously in 6 cases, three of them being nonmosaic and three mosaic patients. There was a great variability of expression among the anomalies of these patients. However, the most common anomalies were in the face and joints. A correlation between the severity of expression and percent of monosomic cells was not clear.

Identical twins with the classical form of Schwartz-Jampel syndrome.

The Schwartz-Jampel syndrome is a rare disorder inherited as an autosomal recessive trait. The main clinical features of this syndrome include generalized myotonic myopathy, skeletal dysplasia, blepharophimosis, microstomia, contracture of joints and short stature. This report concerns a pair of female monozygotic twins with Schwartz-Jampel syndrome. Minor physical differences were found in the toes and joints affected. Additionally, both showed severe microcephaly and previously undescribed X-ray manifestations: a small skull, disproportion between skull and facial structures and dysharmonic bone maturation. This is the first report of identical twins with this syndrome.

[Cytogenetic research in couples with recurrent spontaneous gestational losses]. / Investigación citogenética en parejas con péridadas gestacionales espontáneas recurrentes (PGER).

The most common complication of pregnancy is fetal wastage in any of its manifestations. One of the causes of these reproductive losses is the presence of parental chromosomal aberration. The diagnosis of this cause permits appropriate specific risk for the couple reproduction. In this study, cytogenic analysis were performed to a group of couples with fetal wastage of unknown, to know whether some parental chromosomic aberrations were the etiologic cause of them. Were included 173 couples with two or more reproductive failures. In all couples, metaphase chromosome analysis of peripheral blood was performed, with trypsin-Giemsa banding and C standing. In five women (2.9%) it was found some chromosomal aberration. In all the men and in 168 women the karyotype was normal. In 2.8% of all the subjects it was found some polimorphic chromosome. Routinary chromosomal survey realized to couples with pregnancy looses of unknown cause is important to identify individuals carrying some chromosomal aberration.