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MR imaging of pituitary dwarfism.

The purpose of this study was to determine whether the MR findings of idiopathic pituitary dwarfism correlated with a clinical history of perinatal abnormalities and abnormal levels of pituitary hormones. MR examinations of 18 patients with pituitary dwarfism were performed; these patients were divided into two groups: those with ectopic posterior lobes (group 1) and those with normal posterior lobes (group 2). Among the seven patients in group 1, MR showed hyperintense signal at the median eminence of the hypothalamus, which was regarded as the ectopic posterior lobe of the pituitary gland. The mean anteroposterior length and height of the pituitary gland in group 1 patients were significantly smaller than those dimensions in the normal control group; the pituitary stalk was not detected in three of seven patients. Six of seven patients were products of breech presentation with perinatal asphyxia. The peak serum growth hormone level was less than 5 ng/ml when assessed by insulin-induced hypoglycemia or the clonidine test. MR findings in the 11 patients with pituitary dwarfism and normal posterior lobes were normal except that the mean size of the pituitary gland was slightly smaller than that of normal controls. The clinical history of these patients was normal except for perinatal asphyxia in one case. Our findings in patients with pituitary dwarfism, with or without an ectopic posterior pituitary lobe suggest that the ectopic lobe, visualized as a bright spot at the median eminence of the hypothalamus, may be common when pituitary dwarfism follows perinatal anoxic/ischemic episodes.

Adolescent↗

[Thanatophoric Dwarfism (author's transl)].

Four cases of thanatophoric dwarfism which appeared between 1974 and 1977 are described. Thanatophoric dwarfism was firstly described in 1967. In the mean-time there are reports about 44 cases. The frequency of thanatophoric dwarfism is considered to be 1 to 6393 newborns. There is no clear evidence about the occurrence of thanatophoric dwarfism, chromosone patterns have been always normal. This type of dwarfism is differentiated from other similar syndromes.

Diagnosis, Differential↗

[A new (brachymelic) type of primordial dwarfism (author's transl)].

Second report of an apparently new type of primordial dwarfism characterized by severe intrauterine and postnatal growth retardation, striking craniofacial deformities and a peculiar osteochondrodysplasia. The major clinical findings are microcephaly, hypotrichosis, bulging eyes, prominent nose, micrognathia and short extremities. The osteochondrodysplasia is characterized by short and bowed humeri and femora with absent ossification of the femoral necks, small and dysplastic iliac wings, strikingly retarded ossification of the epiphyses and shortened metacarpal I and middle phalanges II-V. Possible this condition is caused by the homozygous state of mutant gene. The brachymelic type of primordial dwarfism differs from other forms of primordial dwarfism (particularly from case I of Seckel) by its skeletal abnormalities. The cases described by Seckel (and sometimes referred to as Seckel or bird-headed dwarfism) are heterogenous: Seckel dwarfism apparently does not exist as a nosologic entity.

Abnormalities, Multiple↗

Prenatal sonographic diagnosis of diastrophic dwarfism.

A healthy 27-year-old pregnant woman underwent sonographic examination because her uterine size was large for 20 weeks' menstrual age. Sonograms showed short fetal limbs with hitchhiker thumbs and toes, thoracic scoliosis, clubbed feet, and polyhydramnios. The ossification of all bony structures appeared normal, and there was no evidence of fractures. On the basis of these sonographic findings, we diagnosed skeletal dysplasia and short-limbed dwarfism, most likely diastrophic dwarfism. We counseled the parents, and the pregnancy was continued. At 37 weeks menstrual age, the patient vaginally delivered a male infant that weighed 2,560 g. The infant survived with respiratory support during his first few days of life. Postnatal physical and radiologic examinations confirmed the prenatal diagnosis of diastrophic dwarfism. Sonography is the modality of choice for prenatal detection of diastrophic dwarfism.

Abnormalities, Multiple↗

Heterogeneity of Dyggve-Melchior-Clausen dwarfism.

Sibs with apparent Dyggve-Melchior-Clausen (DMC) dwarfism and normal intelligence are described. Three other familial and 3 sporadic cases with DMC dwarfism and normal intelligence are known. Twelve familial and 9 sporadic cases are known with the usual combination of DMC dwarfism and severe mental retardation. Since the two conditions appear to breed true they seem to be genetically different. We propose to name the former "Smith-McCort dwarfism" to clearly distinguish it from the DMC syndrome in which mental retardation is a constituent part. Both conditions are inherited as autosomal recessive traits. Spinal cord compression due to atlantoaxial instability is a serious and preventable complication of both disorders.

Adult↗

Antenatal diagnosis of short-limb dwarfism: sonographic approach.

Based on the findings in 12 patients with skeletal dysplasia diagnosed antenatally, the authors propose a tailored approach to the evaluation of foetuses with shortened long bones, depending on the time of discovery, the degree of shortening and the associated findings. During the second trimester, a very short femur [2 standard deviations (SD) - 5 mm and less] most probably corresponds to a bone dysplasia, although the differential diagnosis is mainly early intra-uterine growth retardation, and the foetal skeleton should be surveyed completely in order to find supplementary features suggestive of dwarfism. Anomalies of long bones in their shape, thickness or contour, or spinal ossification disorders or undermineralisation (best evaluated at the level of calvarial bones) are most helpful in determining the type of dysplasia. A short femur (between 2 SD and 2 SD - 4 mm) may indicate growth retardation, a chromosomal anomaly or dwarfism. Follow-up examinations are mandatory in order to differentiate between them. During the third trimester a very short femur may indicate a bone dysplasia and the work-up should be the same as in the second trimester. A short femur may correspond to dwarfism of late development, a growth-retarded foetus or constitutional shortness. Various ratios, especially that of the femur/foot, are helpful in differentiating between them. In case of previous family history, a short or very short femur usually indicates recurrence of the dwarfism. In all cases of antenatal diagnosis, confirmation of the sonographic findings should be obtained either by foetal or neonatal radiographs. The approach proposed by the authors should provide sufficient information to counsel the family not only for the ongoing pregnancy but also for subsequent ones.

Bone and Bones↗

Laron dwarfism and mutations of the growth hormone-receptor gene.

Laron dwarfism is associated with resistance to growth hormone (GH). To investigate its genetic basis, we used genetic linkage to test whether the disorder results from a defect in the gene for the human GH receptor. Denaturing gradient gel electrophoresis and sequencing of specific GH-receptor-gene fragments allowed us to characterize specific intragenic DNA markers in 35 control subjects of Mediterranean descent, for use in linkage studies. In two Mediterranean families in which the parents were consanguineous and some of the children had Laron dwarfism, the disease trait and DNA polymorphisms were inherited together. Moreover, an analysis of the GH-receptor-gene RNA transcripts in lymphocytes from one of these families allowed us to identify a thymidine-to-cytosine substitution that generated a serine in place of a phenylalanine at position 96 in the extracellular coding domain of the mature protein. This defect probably affects the receptor adversely and is probably responsible for the lack of plasma GH-binding activity in the patients. This mutation was not found in the GH-receptor genomic sequences of seven unrelated subjects with Laron dwarfism who belonged to different population groups. An analysis of the GH-receptor markers in these patients indicated that different gene frameworks (polymorphic sites within the single gene) were associated with the mutant alleles. We conclude that Laron dwarfism is due to abnormalities in the gene for GH receptor, which may differ from family to family.

Base Sequence↗

Characterization of the human growth hormone receptor gene and demonstration of a partial gene deletion in two patients with Laron-type dwarfism.

Laron-type dwarfism is an autosomal recessive genetic disorder that is characterized by high levels of growth hormone and low levels of insulin-like growth factor I in the circulation. Several lines of evidence suggest that this disease is caused by a defect in the growth hormone receptor. In order to analyze the receptor gene in patients with Laron-type dwarfism and with other growth disorders, we have first determined the gene structure in normal individuals. There are nine exons that encode the receptor and several additional exons in the 5' untranslated region. The coding exons span at least 87 kilobase pairs of chromosome 5. Characterization of the growth hormone receptor gene from nine patients with Laron-type dwarfism shows that two individuals have a deletion of a large portion of the extracellular, hormone binding domain of the receptor gene. Interestingly, this deletion includes nonconsecutive exons, suggesting that an unusual rearrangement may have occurred. Thus, we provide direct evidence that Laron-type dwarfism can result from a defect in the structural gene for the growth hormone receptor.

Adult↗

Rescue from dwarfism by thyroid function compensation in rdw rats.

The rdw rat was initially reported as having hereditary dwarfism caused by pituitary dysfunction. Subsequent studies on the rdw rat, however, have demonstrated that the primary cause of rdw dwarfism is present in the thyroid gland but not in the pituitary gland. The primary cause of rdw rat disorders is a missense mutation of the thyroglobulin (Tg) gene by a one-point mutation. In the present study, we attempted to rescue the dwarfism of the rdw rats using a diet supplemented with thyroid powder (T-powder) and a thyroid graft (T-graft). The infants of the rdw rat were successfully raised to a mature stage body weight, accompanied by elevation of serum growth hormone (GH) and prolactin (PRL), by the T-powder. Furthermore, the T-graft successfully increased the body weight with fertility. The serum GH and PRL levels in the T-graft rdw rat significantly increased. The serum thyroid-stimulating hormone (TSH) levels in the T-graft rdw rat were significantly decreased but were significantly higher than those in the control rat. The GH and PRL mRNA expression in the rdw rat with the T-graft was virtually the same as that of the control, but the TSH beta mRNA differed from that of the control rats. Thus, the dwarfism in the rdw rat is rescued by thyroid function compensation, such as that afforded by T-powder and T-graft.

Animals↗

Metatropic dwarfism, the Kniest syndrome and the pseudoachondroplastic dysplasias.

Metatropic dwarfism, the Kniest syndrome, and pseudoachondroplastic dysplasia are specific chondrodystrophic disorders that have in common dysplasia of the metaphyses, epiphyses, and vertebrae. Metatropic dwarfism and the Kniest syndrome have been confused with Morquio's disease and with each other in the past, but can be easily distinguished on the basis of radiographic features, clinical features, and cartilage pathology. The pseudoachondroplastic dysplasias are associated with short limbed dwarfism and have been confused with achondroplastic dwarfism, but can be readily distinguished on the basis of the normal head, delayed age of onset, the typical radiographic features and the cartilage pathology.

Cartilage↗

[Campomelic dwarfism. Its placement in the heterogeneous group of congenital bowing of the limbs].

The campomelic (camptomelic) dwarfism is a rare congenital syndrome which includes, in addition to typical angulations of femora and tibiae (campomelia or camptomelia = bowed or bent limbs), other skeletal abnormalities and visceral lesions, particularly of the brain and of the respiratory tract, which are almost always responsible of early death. Congenital bowing of limbs are seen in various conditions: as isolated deformity (or component of a strictly localised deformity); as integrating part of a more extensive syndrome (the campomelic dwarfism falls within this subgroup); as secondary element of complex syndromes, such as the severe congenital demineralizations of the skeleton. The differential diagnosis must take into account this various conditions, together with other congenital dwarfisms, particularly those incompatible with life (see table 1 e 2). A typical case of campomelic dwarfism is presented.

Bone and Bones↗

Genetic forms of pituitary dwarfism.

Pituitary dwarfism represents a genetically heterogeneous group of disorders which may be classified on the basis of: associated developmental anomalies or degenerative disease; deficiency of, or peripheral insensitivity to HGH; the number of deficient hormones; the associated metabolic disturbances; and the mode of inheritance. Hereditary forms of pituitary dwarfism include: congenital absence of the pituitary, panhypopituitary dwarfism (autosomal and X-linked recessive forms), isolated HGH deficiency (Types I and II), Laron type of dwarfism, and peripheral unresponsiveness to HGH (the African Pygmies).

Adrenocorticotropic Hormone↗

[Dyssegmental dwarfism. A new case].

In a 3 1/2 month old child with micromelic dwarfism, a case of dyssegmental dwarfism is reported. This affection is characterized, on one hand, by a shortening and a squat aspect of long bones with diaphyseal curve, and on the other hand, by a trouble of vertebral segmentation associated to a variability in the size of vertebral bodies. The differential diagnosis appears adequate to differentiate the dyssegmental dwarfism from other types of neonatal chondrodysplasia, in particular from Kniest syndrome and micrognathia dwarfism.

Bone and Bones↗

[Familial mesomelial dwarfism (Nievergelt syndrome)].

Familial mesomelic dwarfism was first described in 1944 by K. NIEVERGELT, who reported on a father and 3 sons by 3 different mothers who had shortening of the middle segment limbs. in the present study the family described by NIEVERGELT in 1944 is reevaluated and the mode of inheritance investigated over a period of 3 generations. Six patients with mesomelic dwarfism were found out of 43 family members. Two patients, a son of the first patient with mesomelic dwarfism and his son, were seen at our institution. Both presented a rare deformity-combination of the upper and lower extremities. In the upper extremities radio-ulnar synostosis, asymmetrically shaped elbow joints, subluxations of the radial head and a deficient supination capacity of the forearm were diagnosed. The deformities were nearly symmetrical, but a slight predilection for the left forearm was noted. In the lower extremities atypical club-feet with supination of the forefeet, shortening of tibia and fibula and marked synostosis of tarsal and metatarsal bones were seen. The legs were rhombic and supination and pronation of the forefeet were severely reduced. Synostosis of the tibia and fibula and deformities of the toes were found in both patients. The mode of inheritance was considered to be autosomal dominant with high penetrance. It is concluded that familial mesomelic dwarfism is an autosomal dominant disease of the upper and lower limbs with atypical club-feet, marked radio-ulnar, tibia-fibular and tarsal synostosis and deformities of the elbow joints.

Chromosome Aberrations↗

Intrauterine diagnosis of short-limbed dwarfism.

Ten short-limbed fetuses caused by skeletal dysplasia were diagnosed prenatally from September 1984 through July 1988. The final diagnosis was thanatophoric dwarfism in 7 cases and osteogenesis imperfecta congenita in 3 cases. The diagnosis was based on sonographic findings in all cases and postnatal radiography was performed in 3 cases for further confirmation. Sonographic examinations revealed markedly shortened limbs and other associated abnormalities, including abnormal skull appearance, pear-shaped chest with protuberant abdomen, polyhydramnios and hydrops in fetuses with thanatophoric dwarfism. Fetuses with osteogenesis imperfecta congenita were characterized by fractures of the long bones. These findings were helpful in making the specific diagnosis of short-limbed dwarfism. According to our experience, sonographic examination is effective in the prenatal diagnosis of short-limbed dwarfism.

Adult↗

Missing secretory granules, dilated endoplasmic reticulum, and nuclear dislocation in the thyroid gland of rdw rats with hereditary dwarfism.

Previous studies on the rdw rat have suggested that its dwarfism is caused primarily by dysfunction of the thyroid gland. In this study, rat thyroid glands were analyzed endocrinologically and morphologically to clarify the primary cause of dwarfism in the rdw rat. The rdw rat showed lowered thyroid hormone (T4 and T3) levels but elevated TSH in serum. The rdw thyroid gland was almost proportional in size and it was not goiter in gross inspection. Our histological investigation produced three results that may lend important evidence in understanding the problem in the thyroid gland of rdw rats. First of all, secretory granules could not be detected in the follicular epithelial cells of the rdw. Secondly, thyroglobulin was found at very low levels in the follicular lumen by immunohistochemical analysis. In contrast, it could be detected in a substantial quantity inside the dilated rER and in the huge vacuoles that are formed by swelling of the rough endoplasmic reticulum (rER) at the basal side of the follicular epithelial cells. Additionally, the nucleus of the follicular epithelial cells was pressed to the luminal side by the enlarged rER. These morphological changes would indicate that the transport of thyroglobulin is stopped at or before the formation of the secretory granules and thyroglobulin is not secreted into the follicular lumen. The rdw characterization strongly supports that rdw dwarfism is induced by hypothyroidism due to some defect(s) in the thyroid gland.

Animals↗

Osteodysplastic primordial dwarfism: report of a further case with manifestations similar to those of types I and III.

We describe a male infant with microcephalic osteodysplastic primordial dwarfism. The clinical and radiological manifestations most closely resemble those of the patient described by Winter et al. to have manifestations overlapping with both osteodysplastic primordial dwarfism types I and III. The classification of the patient within the spectrum of osteodysplastic primordial dwarfism is discussed and the distinctive neuropathology documented.

Abnormalities, Multiple↗

Becker and limb-girdle muscular dystrophy associated with pituitary dwarfism.

In 1981 a report appeared of a patient with Duchenne muscular dystrophy associated with dwarfism caused by growth hormone deficiency, in whom the muscular disease was unusually benign. The authors suggested that the benign course might be related to the growth hormone deficiency and dwarfism. Other authors later supported this idea, having observed that in dystrophic mice and hamsters with congenital and experimentally induced pituitary dwarfism, respectively, pathological expressions of the dystrophy were markedly reduced. In this paper one case of Becker and one of limb-girdle dystrophy, each associated with short stature and growth hormone deficiency are described. In these cases the disease did not have a particularly benign course. It is concluded that caution is necessary, at least in certain cases, before an association between reduced muscular growth and the dystrophic process can be assumed.

Adolescent↗