If these DNA mutations are left unchecked, some cells can divide uncontrollably, forming tumors (cancers). Further mutations in the DNA could lead to malignant cells that can travel to, and develop cancer in, different areas of the body. Many individuals with Li–Fraumeni syndrome have been shown to be heterozygous for a TP53 mutation. Recent studies have shown that 60% to 80% of classic LFS families harbor detectable germ-line TP53 mutations, the majority of which are missense mutations in the DNA-binding domain. These missense mutations cause a decrease in the ability of p53 to bind to DNA, thus inhibiting the normal TP53 mechanism. Unique Brazilian mutation: Although other mutations leading to Li–Fraumeni syndrome have been found outside the DNA-binding domain, a mutation at codon 337 of the tetramerization domain of TP53 has shown a particularly high frequency. The tetramerization domain plays a major role in the oligomerization of the p53 protein, which exists as a tetramer. This mutation has only been found in Brazilian families, and is located in exon 10 of the TP53 gene. The mutation causes an amino acid change from arginine to histidine at codon 337. With pH in the low to normal physiological range (up to 7.5), the mutant protein forms normal oligomers and retains its suppressor function. However, at a high physiological pH, p53 is unable to assemble into a tetramer. This unique feature may contribute to why families with this particular mutation often show incomplete penetrance.
Heart-hand syndrome, Spanish type, also known as heart-hand syndrome type 3 or III, is a very rare genetic disorder which is characterized by heart, hand, and sometimes feet abnormalities. It is a type of heart-hand syndrome, a class of genetic disorders characterized by cardiac malformations and hand malformations. Only one family with the disorder has been reported in medical literature. Description
People with this disorder have symptoms that affect the heart, hands and feet. These include:

Heart
Sick sinus
Bundle branch block

Hands
Brachydactyly which resembles brachydactyly type C
Abnormal development of the middle phalanges of the fingers
Accessory ossicle on the proximal phalange of the index finger. Feet
Subtle feet anomalies such as syndactyly

Etimology
This condition was first discovered by Ruiz de la Fuente et al., when they described a 3-generation family from Spain with the symptoms mentioned above. The cardiac defects varied between family members; 3 members had intraventicular conduction defects and 1 had a sick sinus. In this family, the 2nd and 5th fingers were the most severely affected out of all the fingers. Autosomal dominant inheritance was suspected. == References ==