Definition and diagnosis of the Brachmann-De Lange syndrome.

We have classified patients referred for suspicion of the Brachmann-De Lange syndrome (BDLS) into two groups using techniques of numerical taxonomy. Patients with the syndrome share an array of abnormal characteristics, and those without it have different abnormal characteristics. A group of 30 characters that best distinguish the two groups of patients was used to construct a diagnostic index. The index score is expected to divide 99% of patients into those with and without the syndrome, leaving 1% in a "zone of doubt." All 46 patients used to construct the index and 16 new patients had scores in either the BDLS or non-BDLS range and none were in the zone of doubt. A previously published index using metacarpal-phalangeal measurements, although less discriminatory, confirmed our findings in 84% of 25 patients tested, the remainder having scores in the zone of doubt for that index.

A diagnostic index for Down syndrome.

We have made use of eight phenotypic findings of Down syndrome to develop an effective diagnostic index. We estimate that about 95% of patients who are suspected of having the syndrome can be categorized as having or not having it with 99.9% confidence. One can thereby make a fast clinical diagnosis on the majority of suspects before karyotyping is complete, allowing one to inform parents soon after birth and, in some instances, to make medical decisions about life-threatening defects. Furthermore, one can avoid the expense of chromosome studies on most patients who do not have the syndrome, unless there are other indications for chromosome studies. The eight features used in the index include three dermatoglyphic traits (hallucal and forefinger pattern, and palmar triradius), two measurements of physical traits (ear length and internipple distance), and three other clinical findings (Brushfield spots, wide-spaced first toe, and excess back neck skin).