Association between altered placental human chorionic gonadotrophin (hCG) production and the occurrence of cryptorchidism: a retrospective study.

BACKGROUND: An increase in cryptorchidism has been reported in many countries. One mechanism could be low fetal testosterone production possibly secondary to altered placental human chorionic gonadotrophin (hCG) release. Our Objective was to compare hCG values from maternal blood between boys with cryptorchidism and normal boys. METHODS: Total hCG and α-fetoprotein (AFP) values [12-16 weeks of gestation; from the double test for Down syndrome screening) were compared between cases of cryptorchidism and normal control boys who were matched for maternal age, maternal smoking, gestational age at time of hCG measurement (±1 day), birth weight and birth term. Measurements were performed in a single laboratory; values were expressed as absolute values (KU/L) and multiples of the median (MoM). Boys whose mothers had had a complicated pregnancy were excluded. Groups were compared using the Student's t test. Log transformation was used to normalize hCG, MoM hCG, AFP and MoM AFP distribution, and values were expressed as geometric means (-1, + 1 tolerance factor). RESULTS: Total hCG and MoM hCG levels were significantly lower in the 51 boys with cryptorchidism compared to 306 controls (21.4 (12.3; 37) KU/L vs 27.7 (15.9; 47.9) KU/L and 0.8 (0.5; 1.2) MoM vs 1.0 (0.6; 1.6) MoM, respectively, p < 0.01). By contrast, AFP and MoM AFP levels were similar between groups. CONCLUSION: This study showed a link between low maternal serum hCG levels and cryptorchidism in boys from uncomplicated pregnancy, while normal AFP levels indicated a normal fetoplacental unit. Whether these abnormalities were due to endogenous or exogenous factors remains to be determined.

Novel molecular diagnostic approaches for X-linked centronuclear (myotubular) myopathy reveal intronic mutations.

X-linked centronuclear myopathy (XLMTM), also called myotubular myopathy, is a severe congenital myopathy characterized by generalized hypotonia and weakness at birth and the typical histological finding of centralization of myo-nuclei. It is caused by mutations in the MTM1 gene encoding the 3-phosphoinositides phosphatase myotubularin. Mutations in dynamin 2 and amphiphysin 2 genes lead to autosomal forms of centronuclear myopathy (CNM). While XLMTM is the most frequent and severe form of CNM, no mutations are found in about 30% of patients by sequencing all MTM1 exons. Moreover, the impact of MTM1 sequence variants is sometimes difficult to assess. It is thus important to devise a complete molecular diagnostic strategy that includes analysis of the myotubularin transcript and protein expression. We therefore developed novel antibodies against human myotubularin and showed that they are able to detect the endogenous protein by direct Western blot from muscle samples and from cultured cells. In conjunction with RT-PCR analysis we validated the consequences of missense and splice mutations on transcript integrity and protein level. We also detected and characterized a novel deep intronic mutation consisting of a single nucleotide change that induces exonisation of a conserved intronic sequence. Patients with centronuclear myopathy and no molecular diagnosis should be investigated for MTM1 defects at the cDNA and protein level.

Mucopolysaccharidosis type IIID: 12 new patients and 15 novel mutations.

Mucopolysaccharidosis III D (Sanfilippo disease type D, MPS IIID) is a rare autosomal recessive lysosomal storage disorder previously described in only 20 patients. MPS IIID is caused by a deficiency of N-acetylglucosamine-6-sulphate sulphatase (GNS), one of the enzymes required for the degradation of heparan sulphate. So far only seven mutations in the GNS gene have been reported. The clinical phenotype of 12 new MPS IIID patients from 10 families was studied. Mutation analysis of GNS was performed in 16 patients (14 index cases). Clinical signs and symptoms of the MPS IIID patients appeared to be similar to previously described patients with MPS III. Early development was normal with onset of behavioral problems around the age of 4 years, followed by developmental stagnation, deterioration of verbal communication and subsequent deterioration of motor functions. Sequence analysis of the coding regions of the gene encoding GNS (GNS) resulted in the identification of 15 novel mutations: 3 missense mutations, 1 nonsense mutation, 4 splice site mutations, 3 frame shift mutations, 3 large deletions and 1 in-frame small deletion. They include the first missense mutations and a relatively high proportion of large rearrangements, which warrants the inclusion of quantitative techniques in routine mutation screening of the GNS gene.

Very low alpha-fetoprotein in Down syndrome maternal serum screening.

OBJECTIVE: To establish the frequency of very low maternal serum AFP and to differentiate congenital AFP deficiency from those diseases known to be associated with low AFP. METHODS: AFP values below 2 microg/L and borderline values up to 3 microg/L were retrospectively analysed in 839 773 singleton pregnancies included in a programme for routine screening of trisomy 21 maternal serum markers. RESULTS: Serum AFP was undetectable (< or =2 microg/L) in 8 cases, giving a frequency of 1/105 000. The calculated risk of Down syndrome was > or =1/250 in 5 cases. Fetal karyotype was normal. Seven of these pregnancies went to term (39-41 weeks) uneventfully, and birth weight was normal (3050-4110 g). In the 8th case, fetal death occurred at 35 weeks due to severe maternal diabetes. AFP levels between 2.1 and 3.0 microg/L were noted in 7 other cases. The calculated risk of Down syndrome was > or =1/250 in 5 cases, and fetal karyotype was normal. Pregnancies went to term in 4 cases (33-41 weeks), and birth weight was normal (3000-3380 g). In 3 cases, low hCG (<0.6 MoM) was associated with low AFP, and fetal death occurred at 15 to 16 weeks. CONCLUSION: Once technical errors have been excluded (repeat assay in a second run, calcium assayed to exclude the interference of EDTA for fluorimetric methods, dilution to exclude interfering antibodies, running on an alternative analyser, checking a second sample), very low second-trimester maternal serum AFP should prompt ultrasound examination in order to check fetal viability. Congenital AFP deficiency, an extremely rare disorder (1/100 000), should be suspected. It has no consequences for fetal and infant development, and parents should be reassured.