Tricho-rhino-phalangeal syndrome (TRPS) is characterized by craniofacial and skeletal abnormalities. Three subtypes have been described: TRPS I, caused by mutations in the TRPS1 gene on chromosome 8; TRPS II, a microdeletion syndrome affecting the TRPS1 and EXT1 genes; and TRPS III, a form with severe brachydactyly, due to short metacarpals, and severe short stature, but without exostoses. To investigate whether TRPS III is caused by TRPS1 mutations and to establish a genotype-phenotype correlation in TRPS, we performed extensive mutation analysis and evaluated the height and degree of brachydactyly in patients with TRPS I or TRPS III. We found 35 different mutations in 44 of 51 unrelated patients. The detection rate (86%) indicates that TRPS1 is the major locus for TRPS I and TRPS III. We did not find any mutation in the parents of sporadic patients or in apparently healthy relatives of familial patients, indicating complete penetrance of TRPS1 mutations. Evaluation of skeletal abnormalities of patients with TRPS1 mutations revealed a wide clinical spectrum. The phenotype was variable in unrelated, age- and sex-matched patients with identical mutations, as well as in families. Four of the five missense mutations alter the GATA DNA-binding zinc finger, and six of the seven unrelated patients with these mutations may be classified as having TRPS III. Our data indicate that TRPS III is at the severe end of the TRPS spectrum and that it is most often caused by a specific class of mutations in the TRPS1 gene.

Thirteen male newborns of a family spanning five generations revealed a syndrome consisting in elevated birth weight and length, a disproportionately large head with coarse, distinctive facies, short neck, slight obesity, and broad, short hands and feet. The affected who reached adulthood attained heights of about 2 m; their unusual facial and general appearance and the clumsiness of all their motions, remarkable during infancy and childhood, had become somewhat less conspicuous. In all but one affected individual, intellectual development was normal. In two index cases neither clinical nor laboratory evaluations revealed a basic defect. X-linked recessive inheritance is most probable.

The hereditary deficiency of 3-hydroxy-3-methylglutaryl (HMG) CoA lyase (HL; OMIM 246450 [http://www3.ncbi.nlm.nih. gov:80/htbin-post/Omim/dispmim?246450]) results in episodes of hypoketotic hypoglycemia and coma and is reported to be frequent and clinically severe in Saudi Arabia. We found genetic diversity among nine Saudi HL-deficient probands: six were homozygous for the missense mutation R41Q, and two were homozygous for the frameshift mutation F305fs(-2). In 32 non-Saudi HL-deficient probands, we found three R41Q alleles and also discovered four other deleterious point mutations in codons 41 and 42: R41X, D42E, D42G, and D42H. In purified mutant recombinant HL, all four missense mutations in codons 41 and 42 cause a marked decrease in HL activity. We developed a screening procedure for HL missense mutations that yields residual activity at levels comparable to those obtained using purified HL peptides. Codons 41 and 42 are important for normal HL catalysis and account for a disproportionate 21 (26%) of 82 of mutant alleles in our group of HL-deficient probands.

Spontaneous growth of 141 untreated girls with Turner syndrome was analysed. Of the patients 25% were born prematurely; their weight and height were normal when compared to prematurely born healthy infants. However, birth weight and height was significantly retarded in Turner patients born at term. A curve for height and growth velocity for the age range 0-16 years was constructed with a sensitive statistical method. By use of a mathematical model equations were created for calculating z-scores and the related percentiles for the height of individual patients at given age. Median height of 18 untreated patients at 18 years was 143.8 cm. Analysis of growth velocity revealed a minor but significant growth spurt at the age of 12.5 years. This growth spurt was also detectable in patients without signs of spontaneous puberty and occurred later in patients with 45,X0 karyotype. Bone age progression was linear up to the age of 7.5 years and decelerated thereafter.

In patients with macrocephaly at birth or rapidly developing within the first weeks of life, US should be performed as the primary imaging modality. Cyst-like bilateral widening of the sylvian fissures is the first sign of GA-I, followed by progressive fronto-temporal and ventricular enlargement. These patients should be screened for GA-I in order to initiate treatment in the asymptomatic stage.