Consumer costs for genetic services.

Since the mid-1970's, inflation and changing patterns of subsidies for genetic service centers in the United States have increased the costs of these services for patients and insurers. We have monitored this trend by periodically surveying the providers of these services to determine their current billing rates. We report here recent rates for cytogenetic laboratory services as well as for clinical in- and outpatient genetic consultations. Prices for the main laboratory and consultation services are approximately twice their 1976 level, but these increases parallel those of medical care. The inflationary trend is slowing. Geographic variations in pricing differences in charges between M.D.'s and Ph.D's, and certain personnel trends in genetic centers are apparent in our data.

Fragile X syndrome: growth, development, and intellectual function.

We collected data on growth, psychomotor development, speech and language development, and intellectual function on a cohort of 100 males with the fragile X chromosome and 95 carrier females. The data include information on prenatal growth (33 males), growth during the preadult years (32 males), psychomotor development during the first 2 years (25 males), speech and language development (15 males and 5 females), and intellectual function (93 males, 33 females, and 10 obligate carriers who were cytogenetically normal). Birth measurements appeared normal when plotted on the Usher/McLean curves of newborn infants (mean head circumference - OFC - at 40th centile, length at 60th centile and weight at 55th centile). Following birth, OFC rose above the 50th percentile and continued above average throughout the preadult years, whereas average length was above average for the first 5 years only and weight did not deviate from the normal mean. Psychomotor development lagged behind the norm from birth with affected males requiring nearly twice as long as expected to sit alone, walk unassisted, and say first words clearly. All males and females studied had significant language delay; all except one male had abnormalities of articulation. All on whom a clear voice sample was obtained had low voice pitch, and 80% had a hoarse or harsh quality of voice. Five males had word repetitions or perseverative speech during the preadult years. The mean IQ of the 93 males studied was 33 and regression analysis demonstrated a decrease in intellectual performance with age. Four fifths of the female carriers who expressed the fra(X) had intellectual performance in the mentally retarded range and showed similar decrease in performance with age. Obligate female carriers who did not express the fra(X) site had normal IQs (IQ 102 +/- 13.3).

Oligohydramnios sequence (Potter's syndrome): case clustering in northeastern Tennessee.

The oligohydramnios sequence (OS) is manifest in newborns when prolonged oligohydramnios has been present during pregnancy. The most important signs are an infant small for gestational age, with wrinkled skin, Potter facies, compression deformities of the limbs, and respiratory distress caused by pulmonary hypoplasia. The recurrence rate of kidney conditions implicated in OS depends on the severity of the condition in the previously affected sib. While absent or encysted kidneys (Potter types II and IV) are incompatible with life, chronic leakage of amniotic fluid may result in a viable infant who shows some signs of OS. The usual incidence of absent or encysted kidneys is 1 per 6,250 births. This rate was exceeded recently in northeastern Tennessee, in a clustering of cases for which no environmental causes are evident.

Non-mosaic trisomy 20 in amniotic fluid cultures with minor anomalies in the fetus.

A non-mosaic trisomy 20 was discovered in all cells in two separate cultures from an age-related genetic amniocentesis. Karyotypes of cells obtained via amniocentesis at the time of termination and of cells cultured from the placenta gave the same unambiguous results. However, the fetus, under macro- and microscopic analysis, showed only two minor anomalies: left simian crease and low-set ears. These findings are more suggestive of a normal or at most mosaic trisomy 20 state. The significance of this finding for prenatal diagnosis is discussed.

The parental origin and mechanism of formation of three dicentric X chromosomes.

Cytogenetic and molecular analyses of three dicentric X chromosomes were performed in an attempt to identify the parental origin and mechanism of formation of the aberrant chromosomes. Results indicate that, in these three cases, the dicentric chromosomes were formed by chromatid breakage and reunion of sister chromatids at the breakpoint. In two cases the abnormal chromosomes were paternal in origin; in the third case the dicentric originated from the maternal X chromosome.