A morpho-etiological description of congenital limb anomalies

BACKGROUND

Limb anomalies rank behind congenital heart disease as the most common birth defects observed in infants. More than 50 classifications for limb anomalies based on morphology and osseous anatomy have been drafted over the past 150 years. The present work aims to provide a concise summary of the most common congenital limb anomalies on a morpho-etiological basis.

PATIENTS AND METHODS

In a retrospective study, 70 newborns with anomalies of the upper and/or lower limbs were ascertained through clinical examination, chromosomal analysis, skeletal surveys and other relevant investigations.

RESULTS

Fetal causes of limb anomalies represented 55.8% of the cases in the form of 9 cases (12.9%) with chromosomal aberrations (trisomy 13, 18 and 21, duplication 13q and deletion 22q) and 30 cases (42.9%) with single gene disorders. An environmental etiology for limb anomalies was diagnosed in 11 cases (15.7%) as amniotic band disruption, monozygotic twin with abnormal circulation, vascular disruption (Poland sequence, sirenomelia and general vascular disruption) and an infant with a diabetic mother. Twenty cases (28.5%) had limb anomalies as part of sporadic syndromes of unknown etiology.

CONCLUSIONS

The morpho-etiological work-up of limb anomalies adopted in the present study is valuable for detecting the cause of the anomaly and is crucial for its prevention. Prevention can be achieved by proper genetic counseling, which includes recurrence risk estimation and prenatal diagnosis.

Sex identification of normal persons and sex reverse cases from bloodstains using FISH and PCR

Sex identification of dry blood is of crucial importance in forensic medicine.

SUBJECTS AND METHODS

Sixty normal (with matching phenotypic and genotypic sex) persons (36 males and 24 females), and 7 cases of sex reverse, i.e., persons with one genotypic sex and ambiguous or external genitalia of the opposite sex (3 phenotypic females with Swyer syndrome and the 46,XY karyotype, and 4 phenotypic Klinefelter-like males with the 46,XX karyotype) were subjected to sex identification by FISH and PCR using bloodstains.

RESULTS

The FISH technique using an X/Y cocktail probe (DXZI & DYZI, Oncor) has identified the sex correctly in 91.69% of interphase nuclei of the 36 males of the study, and in 92.29% of cells of the 24 females and incorrectly identified the 3 phenotypic females with Swyer syndrome as males and the 4 Klinefelter-like males as females. The 60 normal individuals in the study were correctly typed to their phenotypic sex by the 2 PCR methods used, i.e., the single PCR using the amelogenin sequence specific for the X and Y chromosomes and the multiplex PCR using SRY gene (male-specific) and the AR gene (X-specific). Out of the 7 sex reverse cases, one Klinefelter-like male was incorrectly identified by PCR as female due to the absence of amplification of the SRY gene and the amelogenin male-specific 788 bp fragment.

CONCLUSION

The present study demonstrates that both FISH and PCR techniques are fast, easy to perform, reliable and efficient for sex identification but PCR is more accurate. It also emphasises that the sex identified is the genotypic sex which does not necessarily correspond to the phenotypic one and if evidences at the scene of crime indicate opposite sex of the accused, persons with sex reverse have to be ruled out using different X- and Y-specific probes and PCR.

Developmental toxicity of acephate by gavage in mice

Acephate (O,S - dimethyl acetyl phosphoramidothioate), an organophosphate insecticide, was evaluated for its potential to produce developmental toxicity in mice after oral administration. Pregnant ICR (CD-1) mice were given sublethal doses of 0 (distilled water), 7, 14, and 28 mg/kg/day acephate by gavage on Gestation Days 6 through 15. Maternal effects in the 28 mg/kg/day dose group included cholinergic signs, decreased body weight at 15 and 18 days of gestation, and decreased absolute and relative brain weight. Placental weight was also decreased and liver weight was increased in the high dose group. Absolute and relative brain weight was decreased in the 14 mg/kg/day group. No maternal effects were apparent in the 7 mg/kg/day dose group. Maternal exposure to acephate during organogenesis significantly affected the number of implantations, number of live fetuses, number of early resorptions, mean fetal weight, and the incidence of external and skeletal malformations in the 28 mg/kg/day dose group. No visceral malformations were observed. On the basis of the present results acephate showed maternal and developmental toxicity at 28 mg/kg/day.

Trisomy 18 in Kuwait

BACKGROUND

Trisomy 18 (Edwards' syndrome, T18) is the second most common trisomy in man. We describe 118 children with regular T18 who were ascertained clinically and cytogenetically in the Kuwait Medical Genetics Centre during 1980-1997.

METHODS

Ascertainment of T18 cases was performed shortly after birth. Chromosomal studies were carried out in addition to other relevant investigations. To investigate the factors associated with T18, a case-control study was carried out with 131 normal healthy newborns. Studied factors included maternal and paternal age, birth order, abortion, associated malformation, and survival. Multiple logistic regression analysis was used to adjust for confounding between variables.

RESULTS

There was a preponderance of females among T18 cases (female:male ratio 2.1:1). The majority of T18 cases (53%) died before the second week of life. The most common associated anomalies were: congenital heart (38.1%) and gastrointestinal (25.4%). Multiplicity of malformations was also observed. Significant seasonal variation in T18 cases was detected with a peak in spring. Of the 118 T18 cases, 59 were delivered during 1994-1997 (average overall T18 birth prevalence rate 8.95 per 10 000 live births [95% CI: 6.66-11.23]). Concerning maternal age, 30.5% of the T18 cases' mothers were > or =35 years compared to 10.7% in the control group. The difference was statistically significant, P = 0.002. Logistic regression analysis showed that maternal age >30 years was a significant risk factor for T18, after adjusting for confounding with paternal age. Paternal age and abortion were not found to be significant risk factors.

CONCLUSION

Trisomy 18 birth prevalence rate is high in Kuwait with advanced maternal age as a significant risk factor.

Mosaic Turner syndrome: cytogenetics versus FISH

Twenty-two cases with Turner syndrome features were subjected to standard cytogenetic techniques using giemsa trypsin (GTG-) banding then fluorescence in situ hybridization (FISH) using a specific whole-X chromosome painting probe, Quint-Essential Y-specific DNA probe (AMELY) for Yp11.2, alpha-satellite (DYZ3) probe and X/Y cocktail-alpha satellite probe (ONCOR) for confirmation of the initial diagnosis and comparison of the two techniques. Eight cases (36%) showed the same karyotype results by both techniques [5 cases: 45,X/46,XX, 2 cases: 45,X/46,X,i(Xq) and one case with a triple cell line 45,X/46,XX/47,XXX]. In the other 14 cases (64%) the FISH technique has identified a third cell line in 7 cases (32%), delineated the origin of the marker in 5 cases (23%) to be derivative X and clarified the deletion of the Yp11.2 region in 2 cases (9%) with the 45,X/46,XY karyotype. The application of FISH has highlighted the differences between the initial diagnosis based on the standard cytogenetic technique and the final diagnosis determined by the application of DNA probes specific for the X and Y chromosomes. FISH proved useful in detection of the low frequency cell lines which need analysis of a large number of metaphase spreads by GTG-banding, helped in identifying the nature and the origin of the unknown markers which has an important implication in the development of gonadal tumours and delineated the deletion of the Yp11.2 region in the 45,X/46,XY Turner patients.

Triophthalmia and facial clefting: a case report

We describe a Libyan boy with an unusual phenotype of multiple congenital anomalies, including triophthalmia, dolichocephaly, porencephaly, cleft lip/palate, facial asymmetry, micrognathia, and VSD. The reported phenotype is likely to represent a new entity of non-chromosomal syndromic triophthalmia. Other possibilities are discussed.

Deletion 9p, duplication 18q in two sisters resulting from a maternal (9;18) (p22;q21.3) translocation

We have studied two sisters with partial deletion 9p and partial duplication 18q resulting from adjacent 1 segregation of a maternal translocation (9;18) (p22;q21.3). The clinical manifestations identified in our patients were compared with those reported in the literature for 9p- and 18q+ patients involving approximately the same amount of genetic material. There was relatively greater similarity with the 9p- syndrome than with dup (18q) syndrome, but typical characteristics of both conditions were lacking.