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Temtamy SA, Ghali I, Salam MA, Hussein FH, Ezz EHAA, Salah N. Karyotype/phenotype correlation in females with short stature. Clin Genet 1992:41: 147–151. We studied 60 females who presented with short stature. The main aim was to determine the effect of karyotype variation on phenotype. A somatic feature score was calculated for each case depending on the presence of 17 clinical somatic changes known to occur in Turner syndrome. Karyotype studies showed the following results: 45, X (n = 22): 46, XX (n= 11); 45, X/ 46, XX (n= 10); 46, XX/46, Xi(Xq) (n = 4); 46, XX/46, XXq‐ (n = 3); 46, XX/ 46, XXp‐ (n = 2); 46, Xi(Xq) (n = 2); 45, X/46, Xi(Xq) (n = 2); 46, XXp‐(n= 1); 46, XX/47, XXX (n= 1); 46, XXq‐ (n= 1); 45, X/46, X(ry) (n=1). Karyotype/phenotype correlation showed the gradation of severity of clinical phenotype to be related to the number of X chromosomes. The highest somatic scores and the most severe clinical manifestations were noted in cases of pure 45, X Turner and the mildest in 46, XX/ 46, XX(str) mosaics or pure 46,XX, including hypergonadotrophic hypo‐gonadism. Our findings revealed a dosage effect of the X chromosome on phenotype, thus confirming that partial X chromosome inactivation modifies somatic and pubertal development. Our results also support both the additive and interactive hypotheses of karyotype/phenotype correlation.

The enzyme 5 alpha-reductase (5 alpha R), by virtue of its peripheral 5 alpha-reduction of testosterone (T) to dihydrotestosterone (DHT), is believed to play a major role in the differentiation and the subsequent growth of the penis. However, recent studies have reported 5 alpha R deficiency (5 alpha RD) in patients with isolated micropenis and hypothesized that 5 alpha RD is not invariably associated with genital ambiguity. In Egypt, 5 alpha RD has been reported frequently among intersex patients. The aim of this study was to assess the role of 5 alpha RD in the development of micropenis among Egyptian patients with abnormal sexual development. The study included 29 patients who were categorized into three groups (isolated micropenis, 9 patients; microphallus with genital ambiguity, 11 patients; genital ambiguity with normal-sized phallus, 9 patients). Activity of 5 alpha R was assessed by estimating T/DHT ratios in the basal state in pubertal subjects and following human chorionic gonadotropin (HCG) stimulation test in prepubertals. The results showed that the incidence of 5 alpha RD was much higher in cases of ambiguous genitalia with micropenis (5 families out of 10, 50%) than in those with isolated microphallus (1/9, 11.1%) or those with ambiguous genitalia and normal-sized phallus (1/8, 12.5%). In conclusion, the study showed that isolated micropenis is a heterogeneous disorder and that 5 alpha RD, despite its relative prevalence in Egypt, has a minimal role in the aetiology. On the other hand, 5 alpha RD seems to correlate with penile length in intersex cases.

This study investigates the impact of securitization on risk behavior and banking stability. Based on a sample of 174 US commercial banks from 2001 to 2008, we find that a greater recourse to securitization is associated with a deterioration in the quality of American banks' loan portfolios and an increase of the credit risk in their balance sheets. In the other hand, we observe a positive and significant impact of securitization on banking stability. We think that this paradox is due to the fact that different classes of securitized assets lead to heterogeneous effects on American banks' stabilities. Particularly, our results show that mortgage securitization has a positive and significant impact on banking stability, providing thus a support to the implicit recourse hypothesis. Inversely, non mortgage securitization has a negative effect on banking stability because of the reduction of banks' monitoring incentives related to this particular form of securitization.

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